Provided by: drbd-utils_9.22.0-1_amd64 
NAME
drbdsetup - Setup tool for DRBD
SYNOPSIS
drbdsetup new-resource resource [--cpu-mask {val}]
[--on-no-data-accessible {io-error | suspend-io}]
drbdsetup new-minor resource minor volume
drbdsetup del-resource resource
drbdsetup del-minor minor
drbdsetup attach minor lower_dev meta_data_dev meta_data_index [--size {val}]
[--max-bio-bvecs {val}] [--on-io-error {pass_on | call-local-io-error | detach}]
[--fencing {dont-care | resource-only | resource-and-stonith}] [--disk-barrier]
[--disk-flushes] [--disk-drain] [--md-flushes] [--resync-rate {val}]
[--resync-after {val}] [--al-extents {val}] [--al-updates]
[--discard-zeroes-if-aligned] [--disable-write-same] [--c-plan-ahead {val}]
[--c-delay-target {val}] [--c-fill-target {val}] [--c-max-rate {val}]
[--c-min-rate {val}] [--disk-timeout {val}]
[--read-balancing {prefer-local | prefer-remote | round-robin | least-pending | when-congested-remote | 32K-striping | 64K-striping | 128K-striping | 256K-striping | 512K-striping | 1M-striping}]
[--rs-discard-granularity {val}]
drbdsetup connect resource local_addr remote_addr [--tentative] [--discard-my-data]
[--protocol {A | B | C}] [--timeout {val}] [--max-epoch-size {val}]
[--max-buffers {val}] [--unplug-watermark {val}] [--connect-int {val}]
[--ping-int {val}] [--sndbuf-size {val}] [--rcvbuf-size {val}]
[--ko-count {val}] [--allow-two-primaries] [--cram-hmac-alg {val}]
[--shared-secret {val}]
[--after-sb-0pri {disconnect | discard-younger-primary | discard-older-primary | discard-zero-changes | discard-least-changes | discard-local | discard-remote}]
[--after-sb-1pri {disconnect | consensus | discard-secondary | call-pri-lost-after-sb | violently-as0p}]
[--after-sb-2pri {disconnect | call-pri-lost-after-sb | violently-as0p}]
[--always-asbp] [--rr-conflict {disconnect | call-pri-lost | violently}]
[--ping-timeout {val}] [--data-integrity-alg {val}] [--tcp-cork]
[--on-congestion {block | pull-ahead | disconnect}] [--congestion-fill {val}]
[--congestion-extents {val}] [--csums-alg {val}] [--csums-after-crash-only]
[--verify-alg {val}] [--use-rle] [--socket-check-timeout {val}]
drbdsetup disk-options minor [--on-io-error {pass_on | call-local-io-error | detach}]
[--fencing {dont-care | resource-only | resource-and-stonith}] [--disk-barrier]
[--disk-flushes] [--disk-drain] [--md-flushes] [--resync-rate {val}]
[--resync-after {val}] [--al-extents {val}] [--al-updates]
[--discard-zeroes-if-aligned] [--disable-write-same] [--c-plan-ahead {val}]
[--c-delay-target {val}] [--c-fill-target {val}] [--c-max-rate {val}]
[--c-min-rate {val}] [--disk-timeout {val}]
[--read-balancing {prefer-local | prefer-remote | round-robin | least-pending | when-congested-remote | 32K-striping | 64K-striping | 128K-striping | 256K-striping | 512K-striping | 1M-striping}]
[--rs-discard-granularity {val}]
drbdsetup net-options local_addr remote_addr [--protocol {A | B | C}] [--timeout {val}]
[--max-epoch-size {val}] [--max-buffers {val}] [--unplug-watermark {val}]
[--connect-int {val}] [--ping-int {val}] [--sndbuf-size {val}]
[--rcvbuf-size {val}] [--ko-count {val}] [--allow-two-primaries]
[--cram-hmac-alg {val}] [--shared-secret {val}]
[--after-sb-0pri {disconnect | discard-younger-primary | discard-older-primary | discard-zero-changes | discard-least-changes | discard-local | discard-remote}]
[--after-sb-1pri {disconnect | consensus | discard-secondary | call-pri-lost-after-sb | violently-as0p}]
[--after-sb-2pri {disconnect | call-pri-lost-after-sb | violently-as0p}]
[--always-asbp] [--rr-conflict {disconnect | call-pri-lost | violently}]
[--ping-timeout {val}] [--data-integrity-alg {val}] [--tcp-cork]
[--on-congestion {block | pull-ahead | disconnect}] [--congestion-fill {val}]
[--congestion-extents {val}] [--csums-alg {val}] [--csums-after-crash-only]
[--verify-alg {val}] [--use-rle] [--socket-check-timeout {val}]
drbdsetup resource-options resource [--cpu-mask {val}]
[--on-no-data-accessible {io-error | suspend-io}]
drbdsetup disconnect local_addr remote_addr [--force]
drbdsetup detach minor [--force]
drbdsetup primary minor [--force]
drbdsetup secondary minor
drbdsetup down resource
drbdsetup verify minor [--start {val}] [--stop {val}]
drbdsetup invalidate minor
drbdsetup invalidate-remote minor
drbdsetup wait-connect minor [--wfc-timeout {val}] [--degr-wfc-timeout {val}]
[--outdated-wfc-timeout {val}] [--wait-after-sb {val}]
drbdsetup wait-sync minor [--wfc-timeout {val}] [--degr-wfc-timeout {val}]
[--outdated-wfc-timeout {val}] [--wait-after-sb {val}]
drbdsetup role minor
drbdsetup cstate minor
drbdsetup dstate minor
drbdsetup resize minor [--size {val}] [--assume-peer-has-space] [--assume-clean]
[--al-stripes {val}] [--al-stripe-size-kB {val}]
drbdsetup check-resize minor
drbdsetup pause-sync minor
drbdsetup resume-sync minor
drbdsetup outdate minor
drbdsetup show-gi minor
drbdsetup get-gi minor
drbdsetup show {resource | minor | all}
drbdsetup suspend-io minor
drbdsetup resume-io minor
drbdsetup status {resource | all} [--color {val}]
drbdsetup events2 {resource | all}
drbdsetup events {resource | minor | all}
drbdsetup new-current-uuid minor [--clear-bitmap]
DESCRIPTION
drbdsetup is used to associate DRBD devices with their backing block devices, to set up
DRBD device pairs to mirror their backing block devices, and to inspect the configuration
of running DRBD devices.
NOTE
drbdsetup is a low level tool of the DRBD program suite. It is used by the data disk and
drbd scripts to communicate with the device driver.
COMMANDS
Each drbdsetup sub-command might require arguments and bring its own set of options. All
values have default units which might be overruled by K, M or G. These units are defined
in the usual way (e.g. K = 2^10 = 1024).
Common options
All drbdsetup sub-commands accept these two options
--create-device
In case the specified DRBD device (minor number) does not exist yet, create it
implicitly.
new-resource
Resources are the primary objects of any DRBD configuration. A resource must be created
with the new-resource command before any volumes or minor devices can be created.
Connections are referenced by name.
new-minor
A minor is used as a synonym for replicated block device. It is represented in the /dev/
directory by a block device. It is the application's interface to the DRBD-replicated
block devices. These block devices get addressed by their minor numbers on the drbdsetup
commandline.
A pair of replicated block devices may have different minor numbers on the two machines.
They are associated by a common volume-number. Volume numbers are local to each
connection. Minor numbers are global on one node.
del-resource
Destroys a resource object. This is only possible if the resource has no volumes.
del-minor
Minors can only be destroyed if its disk is detached.
attach, disk-options
Attach associates device with lower_device to store its data blocks on. The -d (or
--disk-size) should only be used if you wish not to use as much as possible from the
backing block devices. If you do not use -d, the device is only ready for use as soon as
it was connected to its peer once. (See the net command.)
With the disk-options command it is possible to change the options of a minor while it is
attached.
--disk-size size
You can override DRBD's size determination method with this option. If you need to use
the device before it was ever connected to its peer, use this option to pass the size
of the DRBD device to the driver. Default unit is sectors (1s = 512 bytes).
If you use the size parameter in drbd.conf, we strongly recommend to add an explicit
unit postfix. drbdadm and drbdsetup used to have mismatching default units.
--on-io-error err_handler
If the driver of the lower_device reports an error to DRBD, DRBD will mark the disk as
inconsistent, call a helper program, or detach the device from its backing storage and
perform all further IO by requesting it from the peer. The valid err_handlers are:
pass_on, call-local-io-error and detach.
--fencing fencing_policy
Under fencing we understand preventive measures to avoid situations where both nodes
are primary and disconnected (AKA split brain).
Valid fencing policies are:
dont-care
This is the default policy. No fencing actions are done.
resource-only
If a node becomes a disconnected primary, it tries to outdate the peer's disk.
This is done by calling the fence-peer handler. The handler is supposed to reach
the other node over alternative communication paths and call 'drbdadm outdate res'
there.
resource-and-stonith
If a node becomes a disconnected primary, it freezes all its IO operations and
calls its fence-peer handler. The fence-peer handler is supposed to reach the peer
over alternative communication paths and call 'drbdadm outdate res' there. In case
it cannot reach the peer, it should stonith the peer. IO is resumed as soon as the
situation is resolved. In case your handler fails, you can resume IO with the
resume-io command.
--disk-barrier,
--disk-flushes,
--disk-drain
DRBD has four implementations to express write-after-write dependencies to its backing
storage device. DRBD will use the first method that is supported by the backing
storage device and that is not disabled. By default the flush method is used.
Since drbd-8.4.2 disk-barrier is disabled by default because since linux-2.6.36 (or
2.6.32 RHEL6) there is no reliable way to determine if queuing of IO-barriers works.
Dangerous only enable if you are told so by one that knows for sure.
When selecting the method you should not only base your decision on the measurable
performance. In case your backing storage device has a volatile write cache (plain
disks, RAID of plain disks) you should use one of the first two. In case your backing
storage device has battery-backed write cache you may go with option 3. Option 4
(disable everything, use "none") is dangerous on most IO stacks, may result in
write-reordering, and if so, can theoretically be the reason for data corruption, or
disturb the DRBD protocol, causing spurious disconnect/reconnect cycles. Do not use
no-disk-drain.
Unfortunately device mapper (LVM) might not support barriers.
The letter after "wo:" in /proc/drbd indicates with method is currently in use for a
device: b, f, d, n. The implementations:
barrier
The first requires that the driver of the backing storage device support barriers
(called 'tagged command queuing' in SCSI and 'native command queuing' in SATA
speak). The use of this method can be enabled by setting the disk-barrier options
to yes.
flush
The second requires that the backing device support disk flushes (called 'force
unit access' in the drive vendors speak). The use of this method can be disabled
setting disk-flushes to no.
drain
The third method is simply to let write requests drain before write requests of a
new reordering domain are issued. That was the only implementation before 8.0.9.
none
The fourth method is to not express write-after-write dependencies to the backing
store at all, by also specifying --no-disk-drain. This is dangerous on most IO
stacks, may result in write-reordering, and if so, can theoretically be the reason
for data corruption, or disturb the DRBD protocol, causing spurious
disconnect/reconnect cycles. Do not use --no-disk-drain.
--md-flushes
Disables the use of disk flushes and barrier BIOs when accessing the meta data device.
See the notes on --disk-flushes.
--max-bio-bvecs
In some special circumstances the device mapper stack manages to pass BIOs to DRBD
that violate the constraints that are set forth by DRBD's merge_bvec() function and
which have more than one bvec. A known example is: phys-disk -> DRBD -> LVM -> Xen ->
misaligned partition (63) -> DomU FS. Then you might see "bio would need to, but
cannot, be split:" in the Dom0's kernel log.
The best workaround is to proper align the partition within the VM (E.g. start it at
sector 1024). That costs 480 KiB of storage. Unfortunately the default of most Linux
partitioning tools is to start the first partition at an odd number (63). Therefore
most distributions install helpers for virtual linux machines will end up with
misaligned partitions. The second best workaround is to limit DRBD's max bvecs per BIO
(i.e., the max-bio-bvecs option) to 1, but that might cost performance.
The default value of max-bio-bvecs is 0, which means that there is no user imposed
limitation.
--resync-rate rate
To ensure smooth operation of the application on top of DRBD, it is possible to limit
the bandwidth that may be used by background synchronization. The default is 250
KiB/sec, the default unit is KiB/sec.
--resync-after minor
Start resync on this device only if the device with minor is already in connected
state. Otherwise this device waits in SyncPause state.
--al-extents extents
DRBD automatically performs hot area detection. With this parameter you control how
big the hot area (=active set) can get. Each extent marks 4M of the backing storage.
In case a primary node leaves the cluster unexpectedly, the areas covered by the
active set must be resynced upon rejoining of the failed node. The data structure is
stored in the meta-data area, therefore each change of the active set is a write
operation to the meta-data device. A higher number of extents gives longer resync
times but less updates to the meta-data. The default number of extents is 1237.
(Minimum: 7, Maximum: 65534)
See also drbd.conf(5) and drbdmeta(8) for additional limitations and necessary
preparation.
--al-updates {yes | no}
DRBD's activity log transaction writing makes it possible, that after the crash of a
primary node a partial (bit-map based) resync is sufficient to bring the node back to
up-to-date. Setting al-updates to no might increase normal operation performance but
causes DRBD to do a full resync when a crashed primary gets reconnected. The default
value is yes.
--c-plan-ahead plan_time,
--c-fill-target fill_target,
--c-delay-target delay_target,
--c-max-rate max_rate
The dynamic resync speed controller gets enabled with setting plan_time to a positive
value. It aims to fill the buffers along the data path with either a constant amount
of data fill_target, or aims to have a constant delay time of delay_target along the
path. The controller has an upper bound of max_rate.
By plan_time the agility of the controller is configured. Higher values yield for
slower/lower responses of the controller to deviation from the target value. It should
be at least 5 times RTT. For regular data paths a fill_target in the area of 4k to
100k is appropriate. For a setup that contains drbd-proxy it is advisable to use
delay_target instead. Only when fill_target is set to 0 the controller will use
delay_target. 5 times RTT is a reasonable starting value. Max_rate should be set to
the bandwidth available between the DRBD-hosts and the machines hosting DRBD-proxy, or
to the available disk-bandwidth.
The default value of plan_time is 0, the default unit is 0.1 seconds. Fill_target has
0 and sectors as default unit. Delay_target has 1 (100ms) and 0.1 as default unit.
Max_rate has 10240 (100MiB/s) and KiB/s as default unit.
--c-min-rate min_rate
We track the disk IO rate caused by the resync, so we can detect non-resync IO on the
lower level device. If the lower level device seems to be busy, and the current resync
rate is above min_rate, we throttle the resync.
The default value of min_rate is 4M, the default unit is k. If you want to not
throttle at all, set it to zero, if you want to throttle always, set it to one.
-t, --disk-timeout disk_timeout
If the lower-level device on which a DRBD device stores its data does not finish an
I/O request within the defined disk-timeout, DRBD treats this as a failure. The
lower-level device is detached, and the device's disk state advances to Diskless. If
DRBD is connected to one or more peers, the failed request is passed on to one of
them.
This option is dangerous and may lead to kernel panic!
"Aborting" requests, or force-detaching the disk, is intended for completely
blocked/hung local backing devices which do no longer complete requests at all, not
even do error completions. In this situation, usually a hard-reset and failover is the
only way out.
By "aborting", basically faking a local error-completion, we allow for a more graceful
swichover by cleanly migrating services. Still the affected node has to be rebooted
"soon".
By completing these requests, we allow the upper layers to re-use the associated data
pages.
If later the local backing device "recovers", and now DMAs some data from disk into
the original request pages, in the best case it will just put random data into unused
pages; but typically it will corrupt meanwhile completely unrelated data, causing all
sorts of damage.
Which means delayed successful completion, especially for READ requests, is a reason
to panic(). We assume that a delayed *error* completion is OK, though we still will
complain noisily about it.
The default value of disk-timeout is 0, which stands for an infinite timeout. Timeouts
are specified in units of 0.1 seconds. This option is available since DRBD 8.3.12.
--discard-zeroes-if-aligned {yes | no}
Setting discard-zeroes-if-aligned to no will cause DRBD to always fall-back to
zero-out on the receiving side, and to not even announce discard capabilities on the
Primary, if the respective backend announces discard_zeroes_data=false.
Setting discards-zeroes-if-aligned to yes will allow DRBD to use discards, and to
announce discard_zeroes=true, even on backends that announce
discard_zeroes_data=false.
We used to ignore the discard_zeroes_data setting completely. To not break established
and expected behaviour, the default value is yes.
This option is available since 8.4.7. See also drbd.conf(5).
--disable-write-same {yes | no}
Some disks announce WRITE_SAME support to the kernel but fail with an I/O error upon
actually receiving such a request. This mostly happens when using virtualized disks --
notably, this behavior has been observed with VMware's virtual disks.
When disable-write-same is set to yes, WRITE_SAME detection is manually overriden and
support is disabled.
The default value of disable-write-same is no. This option is available since 8.4.7.
--read-balancing method
The supported methods for load balancing of read requests are prefer-local,
prefer-remote, round-robin, least-pending and when-congested-remote, 32K-striping,
64K-striping, 128K-striping, 256K-striping, 512K-striping and 1M-striping.
The default value of read-balancing is prefer-local. This option is available since
8.4.1.
--rs-discard-granularity bytes
When rs-discard-granularity is set to a non zero, positive value then DRBD tries to do
a resync operation in requests of this size. In case such a block contains only zero
bytes on the sync source node, the sync target node will issue a discard/trim/unmap
command for the area.
The value is constrained by the discard granularity of the backing block device. In
case rs-discard-granularity is not a multiplier of the discard granularity of the
backing block device DRBD rounds it up. The feature only gets active if the backing
block device reads back zeroes after a discard command.
The default value of rs-discard-granularity is 0. This option is available since
8.4.7.
connect, net-options
Connect sets up the device to listen on af:local_addr:port for incoming connections and to
try to connect to af:remote_addr:port. If port is omitted, 7788 is used as default. If af
is omitted ipv4 gets used. Other supported address families are ipv6, ssocks for Dolphin
Interconnect Solutions' "super sockets" and sdp for Sockets Direct Protocol (Infiniband).
The net-options command allows you to change options while the connection is established.
--protocol protocol
On the TCP/IP link the specified protocol is used. Valid protocol specifiers are A, B,
and C.
Protocol A: write IO is reported as completed, if it has reached local disk and local
TCP send buffer.
Protocol B: write IO is reported as completed, if it has reached local disk and remote
buffer cache.
Protocol C: write IO is reported as completed, if it has reached both local and remote
disk.
--connect-int time
In case it is not possible to connect to the remote DRBD device immediately, DRBD
keeps on trying to connect. With this option you can set the time between two retries.
The default value is 10. The unit is seconds.
--ping-int time
If the TCP/IP connection linking a DRBD device pair is idle for more than time
seconds, DRBD will generate a keep-alive packet to check if its partner is still
alive. The default value is 10. The unit is seconds.
--timeout val
If the partner node fails to send an expected response packet within val tenths of a
second, the partner node is considered dead and therefore the TCP/IP connection is
abandoned. The default value is 60 (= 6 seconds).
--sndbuf-size size
The socket send buffer is used to store packets sent to the secondary node, which are
not yet acknowledged (from a network point of view) by the secondary node. When using
protocol A, it might be necessary to increase the size of this data structure in order
to increase asynchronicity between primary and secondary nodes. But keep in mind that
more asynchronicity is synonymous with more data loss in the case of a primary node
failure. Since 8.0.13 resp. 8.2.7 setting the size value to 0 means that the kernel
should autotune this. The default size is 0, i.e. autotune.
--rcvbuf-size size
Packets received from the network are stored in the socket receive buffer first. From
there they are consumed by DRBD. Before 8.3.2 the receive buffer's size was always set
to the size of the socket send buffer. Since 8.3.2 they can be tuned independently. A
value of 0 means that the kernel should autotune this. The default size is 0, i.e.
autotune.
--ko-count count
In case the secondary node fails to complete a single write request for count times
the timeout, it is expelled from the cluster, i.e. the primary node goes into
StandAlone mode. To disable this feature, you should explicitly set it to 0; defaults
may change between versions.
--max-epoch-size val
With this option the maximal number of write requests between two barriers is limited.
Typically set to the same as --max-buffers, or the allowed maximum. Values smaller
than 10 can lead to degraded performance. The default value is 2048.
--max-buffers val
With this option the maximal number of buffer pages allocated by DRBD's receiver
thread is limited. Typically set to the same as --max-epoch-size. Small values could
lead to degraded performance. The default value is 2048, the minimum 32. Increase this
if you cannot saturate the IO backend of the receiving side during linear write or
during resync while otherwise idle.
See also drbd.conf(5)
--unplug-watermark val
This setting has no effect with recent kernels that use explicit on-stack plugging
(upstream Linux kernel 2.6.39, distributions may have backported).
When the number of pending write requests on the standby (secondary) node exceeds the
unplug-watermark, we trigger the request processing of our backing storage device.
Some storage controllers deliver better performance with small values, others deliver
best performance when the value is set to the same value as max-buffers, yet others
don't feel much effect at all. Minimum 16, default 128, maximum 131072.
--allow-two-primaries
With this option set you may assign primary role to both nodes. You only should use
this option if you use a shared storage file system on top of DRBD. At the time of
writing the only ones are: OCFS2 and GFS. If you use this option with any other file
system, you are going to crash your nodes and to corrupt your data!
--cram-hmac-alg alg
You need to specify the HMAC algorithm to enable peer authentication at all. You are
strongly encouraged to use peer authentication. The HMAC algorithm will be used for
the challenge response authentication of the peer. You may specify any digest
algorithm that is named in /proc/crypto.
--shared-secret secret
The shared secret used in peer authentication. May be up to 64 characters.
--after-sb-0pri asb-0p-policy
possible policies are:
disconnect
No automatic resynchronization, simply disconnect.
discard-younger-primary
Auto sync from the node that was primary before the split-brain situation
occurred.
discard-older-primary
Auto sync from the node that became primary as second during the split-brain
situation.
discard-zero-changes
In case one node did not write anything since the split brain became evident, sync
from the node that wrote something to the node that did not write anything. In
case none wrote anything this policy uses a random decision to perform a "resync"
of 0 blocks. In case both have written something this policy disconnects the
nodes.
discard-least-changes
Auto sync from the node that touched more blocks during the split brain situation.
discard-node-NODENAME
Auto sync to the named node.
--after-sb-1pri asb-1p-policy
possible policies are:
disconnect
No automatic resynchronization, simply disconnect.
consensus
Discard the version of the secondary if the outcome of the after-sb-0pri algorithm
would also destroy the current secondary's data. Otherwise disconnect.
discard-secondary
Discard the secondary's version.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri algorithm. In case it decides the
current secondary has the correct data, call the pri-lost-after-sb on the current
primary.
violently-as0p
Always honor the outcome of the after-sb-0pri algorithm. In case it decides the
current secondary has the correct data, accept a possible instantaneous change of
the primary's data.
--after-sb-2pri asb-2p-policy
possible policies are:
disconnect
No automatic resynchronization, simply disconnect.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri algorithm. In case it decides the
current secondary has the right data, call the pri-lost-after-sb on the current
primary.
violently-as0p
Always honor the outcome of the after-sb-0pri algorithm. In case it decides the
current secondary has the right data, accept a possible instantaneous change of
the primary's data.
--always-asbp
Normally the automatic after-split-brain policies are only used if current states of
the UUIDs do not indicate the presence of a third node.
With this option you request that the automatic after-split-brain policies are used as
long as the data sets of the nodes are somehow related. This might cause a full sync,
if the UUIDs indicate the presence of a third node. (Or double faults have led to
strange UUID sets.)
--rr-conflict role-resync-conflict-policy
This option sets DRBD's behavior when DRBD deduces from its meta data that a
resynchronization is needed, and the SyncTarget node is already primary. The possible
settings are: disconnect, call-pri-lost and violently. While disconnect speaks for
itself, with the call-pri-lost setting the pri-lost handler is called which is
expected to either change the role of the node to secondary, or remove the node from
the cluster. The default is disconnect.
With the violently setting you allow DRBD to force a primary node into SyncTarget
state. This means that the data exposed by DRBD changes to the SyncSource's version of
the data instantaneously. USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
--data-integrity-alg hash_alg
DRBD can ensure the data integrity of the user's data on the network by comparing hash
values. Normally this is ensured by the 16 bit checksums in the headers of TCP/IP
packets. This option can be set to any of the kernel's data digest algorithms. In a
typical kernel configuration you should have at least one of md5, sha1, and crc32c
available. By default this is not enabled.
See also the notes on data integrity on the drbd.conf manpage.
--no-tcp-cork
DRBD usually uses the TCP socket option TCP_CORK to hint to the network stack when it
can expect more data, and when it should flush out what it has in its send queue.
There is at least one network stack that performs worse when one uses this hinting
method. Therefore we introduced this option, which disable the setting and clearing of
the TCP_CORK socket option by DRBD.
--ping-timeout ping_timeout
The time the peer has to answer to a keep-alive packet. In case the peer's reply is
not received within this time period, it is considered dead. The default unit is
tenths of a second, the default value is 5 (for half a second).
--discard-my-data
Use this option to manually recover from a split-brain situation. In case you do not
have any automatic after-split-brain policies selected, the nodes refuse to connect.
By passing this option you make this node a sync target immediately after successful
connect.
--tentative
Causes DRBD to abort the connection process after the resync handshake, i.e. no resync
gets performed. You can find out which resync DRBD would perform by looking at the
kernel's log file.
--on-congestion congestion_policy,
--congestion-fill fill_threshold,
--congestion-extents active_extents_threshold
By default DRBD blocks when the available TCP send queue becomes full. That means it
will slow down the application that generates the write requests that cause DRBD to
send more data down that TCP connection.
When DRBD is deployed with DRBD-proxy it might be more desirable that DRBD goes into
AHEAD/BEHIND mode shortly before the send queue becomes full. In AHEAD/BEHIND mode
DRBD does no longer replicate data, but still keeps the connection open.
The advantage of the AHEAD/BEHIND mode is that the application is not slowed down,
even if DRBD-proxy's buffer is not sufficient to buffer all write requests. The
downside is that the peer node falls behind, and that a resync will be necessary to
bring it back into sync. During that resync the peer node will have an inconsistent
disk.
Available congestion_policys are block and pull-ahead. The default is block.
Fill_threshold might be in the range of 0 to 10GiBytes. The default is 0 which
disables the check. Active_extents_threshold has the same limits as al-extents.
The AHEAD/BEHIND mode and its settings are available since DRBD 8.3.10.
--verify-alg hash-alg
During online verification (as initiated by the verify sub-command), rather than doing
a bit-wise comparison, DRBD applies a hash function to the contents of every block
being verified, and compares that hash with the peer. This option defines the hash
algorithm being used for that purpose. It can be set to any of the kernel's data
digest algorithms. In a typical kernel configuration you should have at least one of
md5, sha1, and crc32c available. By default this is not enabled; you must set this
option explicitly in order to be able to use on-line device verification.
See also the notes on data integrity on the drbd.conf manpage.
--csums-alg hash-alg
A resync process sends all marked data blocks from the source to the destination node,
as long as no csums-alg is given. When one is specified the resync process exchanges
hash values of all marked blocks first, and sends only those data blocks over, that
have different hash values.
This setting is useful for DRBD setups with low bandwidth links. During the restart of
a crashed primary node, all blocks covered by the activity log are marked for resync.
But a large part of those will actually be still in sync, therefore using csums-alg
will lower the required bandwidth in exchange for CPU cycles.
--use-rle
During resync-handshake, the dirty-bitmaps of the nodes are exchanged and merged
(using bit-or), so the nodes will have the same understanding of which blocks are
dirty. On large devices, the fine grained dirty-bitmap can become large as well, and
the bitmap exchange can take quite some time on low-bandwidth links.
Because the bitmap typically contains compact areas where all bits are unset (clean)
or set (dirty), a simple run-length encoding scheme can considerably reduce the
network traffic necessary for the bitmap exchange.
For backward compatibility reasons, and because on fast links this possibly does not
improve transfer time but consumes cpu cycles, this defaults to off.
Introduced in 8.3.2.
--socket-check-timeout
In setups involving a DRBD-proxy and connections that experience a lot of buffer-bloat
it might be necessary to set ping-timeout to an unusual high value. By default DRBD
uses the same value to wait if a newly established TCP-connection is stable. Since the
DRBD-proxy is usually located in the same data center such a long wait time may hinder
DRBD's connect process.
In such setups socket-check-timeout should be set to at least to the round trip time
between DRBD and DRBD-proxy. I.e. in most cases to 1.
The default unit is tenths of a second, the default value is 0 (which causes DRBD to
use the value of ping-timeout instead). Introduced in 8.4.5.
resource-options
Changes the options of the resource at runtime.
--cpu-mask cpu-mask
Sets the cpu-affinity-mask for DRBD's kernel threads of this device. The default value
of cpu-mask is 0, which means that DRBD's kernel threads should be spread over all
CPUs of the machine. This value must be given in hexadecimal notation. If it is too
big it will be truncated.
--on-no-data-accessible ond-policy
This setting controls what happens to IO requests on a degraded, disk less node (I.e.
no data store is reachable). The available policies are io-error and suspend-io.
If ond-policy is set to suspend-io you can either resume IO by attaching/connecting
the last lost data storage, or by the drbdadm resume-io res command. The latter will
result in IO errors of course.
The default is io-error. This setting is available since DRBD 8.3.9.
primary
Sets the device into primary role. This means that applications (e.g. a file system) may
open the device for read and write access. Data written to the device in primary role are
mirrored to the device in secondary role.
Normally it is not possible to set both devices of a connected DRBD device pair to primary
role. By using the --allow-two-primaries option, you override this behavior and instruct
DRBD to allow two primaries.
--overwrite-data-of-peer
Alias for --force.
--force
Becoming primary fails if the local replica is not up-to-date. I.e. when it is
inconsistent, outdated of consistent. By using this option you can force it into
primary role anyway. USE THIS OPTION ONLY IF YOU KNOW WHAT YOU ARE DOING.
secondary
Brings the device into secondary role. This operation fails as long as at least one
application (or file system) has opened the device.
It is possible that both devices of a connected DRBD device pair are secondary.
verify
This initiates on-line device verification. During on-line verification, the contents of
every block on the local node are compared to those on the peer node. Device verification
progress can be monitored via /proc/drbd. Any blocks whose content differs from that of
the corresponding block on the peer node will be marked out-of-sync in DRBD's on-disk
bitmap; they are not brought back in sync automatically. To do that, simply disconnect and
reconnect the resource.
If on-line verification is already in progress (and this node is "VerifyS"), this command
silently "succeeds". In this case, any start-sector (see below) will be ignored, and any
stop-sector (see below) will be honored. This can be used to stop a running verify, or to
update/shorten/extend the coverage of the currently running verify.
This command will fail if the device is not part of a connected device pair.
See also the notes on data integrity on the drbd.conf manpage.
--start start-sector
Since version 8.3.2, on-line verification should resume from the last position after
connection loss. It may also be started from an arbitrary position by setting this
option. If you had reached some stop-sector before, and you do not specify an explicit
start-sector, verify should resume from the previous stop-sector.
Default unit is sectors. You may also specify a unit explicitly. The start-sector will
be rounded down to a multiple of 8 sectors (4kB).
-S, --stop stop-sector
Since version 8.3.14, on-line verification can be stopped before it reaches
end-of-device.
Default unit is sectors. You may also specify a unit explicitly. The stop-sector may
be updated by issuing an additional drbdsetup verify command on the same node while
the verify is running. This can be used to stop a running verify, or to
update/shorten/extend the coverage of the currently running verify.
invalidate
This forces the local device of a pair of connected DRBD devices into SyncTarget state,
which means that all data blocks of the device are copied over from the peer.
This command will fail if the device is not either part of a connected device pair, or
disconnected Secondary.
invalidate-remote
This forces the local device of a pair of connected DRBD devices into SyncSource state,
which means that all data blocks of the device are copied to the peer.
On a disconnected Primary device, this will set all bits in the out of sync bitmap. As a
side affect this suspends updates to the on disk activity log. Updates to the on disk
activity log resume automatically when necessary.
wait-connect
Returns as soon as the device can communicate with its partner device.
--wfc-timeout wfc_timeout,
--degr-wfc-timeout degr_wfc_timeout,
--outdated-wfc-timeout outdated_wfc_timeout,
--wait-after-sb
This command will fail if the device cannot communicate with its partner for timeout
seconds. If the peer was working before this node was rebooted, the wfc_timeout is
used. If the peer was already down before this node was rebooted, the degr_wfc_timeout
is used. If the peer was successfully outdated before this node was rebooted the
outdated_wfc_timeout is used. The default value for all those timeout values is 0
which means to wait forever. The unit is seconds. In case the connection status goes
down to StandAlone because the peer appeared but the devices had a split brain
situation, the default for the command is to terminate. You can change this behavior
with the --wait-after-sb option.
wait-sync
Returns as soon as the device leaves any synchronization into connected state. The options
are the same as with the wait-connect command.
disconnect
Removes the information set by the net command from the device. This means that the device
goes into unconnected state and will no longer listen for incoming connections.
detach
Removes the information set by the disk command from the device. This means that the
device is detached from its backing storage device.
-f, --force
A regular detach returns after the disk state finally reached diskless. As a
consequence detaching from a frozen backing block device never terminates.
On the other hand A forced detach returns immediately. It allows you to detach DRBD
from a frozen backing block device. Please note that the disk will be marked as failed
until all pending IO requests where finished by the backing block device.
down
Removes all configuration information from the device and forces it back to unconfigured
state.
role
Shows the current roles of the device and its peer, as local/peer.
state
Deprecated alias for "role"
cstate
Shows the current connection state of the device.
dstate
Shows the current states of the backing storage devices, as local/peer.
resize
This causes DRBD to reexamine the size of the device's backing storage device. To actually
do online growing you need to extend the backing storages on both devices and call the
resize command on one of your nodes.
The --size option can be used to online shrink the usable size of a drbd device. It's the
users responsibility to make sure that a file system on the device is not truncated by
that operation.
The --assume-peer-has-space allows you to resize a device which is currently not connected
to the peer. Use with care, since if you do not resize the peer's disk as well, further
connect attempts of the two will fail.
When the --assume-clean option is given DRBD will skip the resync of the new storage. Only
do this if you know that the new storage was initialized to the same content by other
means.
The options --al-stripes and --al-stripe-size-kB may be used to change the layout of the
activity log online. In case of internal meta data this may invovle shrinking the user
visible size at the same time (unsing the --size) or increasing the avalable space on the
backing devices.
check-resize
To enable DRBD to detect offline resizing of backing devices this command may be used to
record the current size of backing devices. The size is stored in files in /var/lib/drbd/
named drbd-minor-??.lkbd
This command is called by drbdadm resize res after drbdsetup device resize returned.
pause-sync
Temporarily suspend an ongoing resynchronization by setting the local pause flag. Resync
only progresses if neither the local nor the remote pause flag is set. It might be
desirable to postpone DRBD's resynchronization after eventual resynchronization of the
backing storage's RAID setup.
resume-sync
Unset the local sync pause flag.
outdate
Mark the data on the local backing storage as outdated. An outdated device refuses to
become primary. This is used in conjunction with fencing and by the peer's fence-peer
handler.
show-gi
Displays the device's data generation identifiers verbosely.
get-gi
Displays the device's data generation identifiers.
show
Shows all available configuration information of a resource, or of all resources.
Available options:
--show-defaults
Show all configuration parameters, even the ones with default values. Normally,
parameters with default values are not shown.
suspend-io
This command is of no apparent use and just provided for the sake of completeness.
resume-io
If the fence-peer handler fails to stonith the peer node, and your fencing policy is set
to resource-and-stonith, you can unfreeze IO operations with this command.
status
Show the status of a resource, or of all resources. The output consists of one paragraph
for each configured resource. Each paragraph contains one line for each resource, followed
by one line for each device, and one line for each connection. The device and connection
lines are indented. The connection lines are followed by one line for each peer device;
these lines are indented against the connection line.
Long lines are wrapped around at terminal width, and indented to indicate how the lines
belongs together. Available options:
--verbose
Include more information in the output even when it is likely redundant or irrelevant.
--statistics
Include data transfer statistics in the output.
--color={always | auto | never}
Colorize the output. With --color=auto, drbdsetup emits color codes only when standard
output is connected to a terminal.
For example, the non-verbose output for a resource with only one connection and only one
volume could look like this:
fs-backoffice role:Primary
disk:UpToDate
peer role:Secondary
replication:Established peer-disk:UpToDate
With the --verbose --statistics options, the same resource could be reported as:
fs-data role:Primary suspended:no
write-ordering:drain
volume:0 minor:1 disk:UpToDate
size:10616472 read:134465 written:144800 al-writes:18 bm-writes:0
upper-pending:0 lower-pending:0 al-suspended:no blocked:no
peer connection:Connected role:Secondary congested:no
volume:0 replication:Established peer-disk:UpToDate resync-suspended:no
received:122596 sent:22204 out-of-sync:0 pending:0 unacked:0
events2
Show the current state of all configured DRBD objects, followed by all changes to the
state.
The output format is meant to be human as well as machine readable. Each line starts with
the event number, which is followed by an asterisk if the event continues in the next
line. The second word in each line indicates the kind of event: exists for an existing
object; create, destroy, and change if an object is created, destroyed, or changed; or
call or response if an event handler is called or it returns. The third word indicates the
object the event applies to: resource, device, connection, peer-device, helper, or a dash
(-) to indicate that the current state has been dumped completely.
The remaining words identify the object and describe the state that he object is in.
Available options:
--now
Terminate after reporting the current state. The default is to continuously listen and
report state changes.
--statistics
Include statistics in the output.
events
Deprecated. If possible, change to the events2 subcommand instead.
Displays every state change of DRBD and all calls to helper programs. This might be used
to get notified of DRBD's state changes by piping the output to another program.
--all-devices
Display the events of all DRBD minors.
--unfiltered
This is a debugging aid that displays the content of all received netlink messages.
new-current-uuid
Generates a new current UUID and rotates all other UUID values. This has at least two use
cases, namely to skip the initial sync, and to reduce network bandwidth when starting in a
single node configuration and then later (re-)integrating a remote site.
Available option:
--clear-bitmap
Clears the sync bitmap in addition to generating a new current UUID.
This can be used to skip the initial sync, if you want to start from scratch. This
use-case does only work on "Just Created" meta data. Necessary steps:
1. On both nodes, initialize meta data and configure the device.
drbdadm -- --force create-md res
2. They need to do the initial handshake, so they know their sizes.
drbdadm up res
3. They are now Connected Secondary/Secondary Inconsistent/Inconsistent. Generate a new
current-uuid and clear the dirty bitmap.
drbdadm new-current-uuid --clear-bitmap res
4. They are now Connected Secondary/Secondary UpToDate/UpToDate. Make one side primary
and create a file system.
drbdadm primary res
mkfs -t fs-type $(drbdadm sh-dev res)
One obvious side-effect is that the replica is full of old garbage (unless you made them
identical using other means), so any online-verify is expected to find any number of
out-of-sync blocks.
You must not use this on pre-existing data! Even though it may appear to work at first
glance, once you switch to the other node, your data is toast, as it never got replicated.
So do not leave out the mkfs (or equivalent).
This can also be used to shorten the initial resync of a cluster where the second node is
added after the first node is gone into production, by means of disk shipping. This
use-case works on disconnected devices only, the device may be in primary or secondary
role.
The necessary steps on the current active server are:
1. drbdsetup new-current-uuid --clear-bitmap minor
2. Take the copy of the current active server. E.g. by pulling a disk out of the RAID1
controller, or by copying with dd. You need to copy the actual data, and the meta
data.
3. drbdsetup new-current-uuid minor
Now add the disk to the new secondary node, and join it to the cluster. You will get a
resync of that parts that were changed since the first call to drbdsetup in step 1.
EXAMPLES
For examples, please have a look at the DRBD User's Guide[1].
VERSION
This document was revised for version 8.3.2 of the DRBD distribution.
AUTHOR
Written by Philipp Reisner <philipp.reisner@linbit.com> and Lars Ellenberg
<lars.ellenberg@linbit.com>
REPORTING BUGS
Report bugs to <drbd-user@lists.linbit.com>.
COPYRIGHT
Copyright 2001-2008 LINBIT Information Technologies, Philipp Reisner, Lars Ellenberg. This
is free software; see the source for copying conditions. There is NO warranty; not even
for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
drbd.conf(5), drbd(8), drbddisk(8), drbdadm(8), DRBD User's Guide[1], DRBD web site[2]
NOTES
1. DRBD User's Guide
http://www.drbd.org/users-guide/
2. DRBD web site
http://www.drbd.org/