Provided by: openafs-client_1.4.1-2_i386
afsd - Initializes the Cache Manager and starts related daemons
afsd << [-blocks <1024 byte blocks in cache] >>>
<< [-files <files in cache] >>>
<< [-rootvol <name of AFS root volume] >>>
<< [-stat <number of stat entries] >>>
[-memcache] << [-cachedir <cache directory] >>>
<< [-mountdir <mount location] >>>
<< [-daemons <number of daemons to use] >>>
[-nosettime] [-verbose] [-rmtsys] [-debug]
<< [-chunksize <log(2) of chunk size] >>>
<< [-dcache <number of dcache entries] >>>
<< [-volumes <number of volume entries] >>>
<< [-biods <number of bkg I/O daemons (aix vm)] >>>
<< [-prealloc <number of ‚Äôsmall‚Äô preallocated blocks] >>>
<< [-confdir <configuration directory] >>>
<< [-logfile <Place to keep the CM log] >>>
[-waitclose] [-shutdown] [-enable_peer_stats]
The afsd command initializes the Cache Manager on an AFS client machine
by transferring AFS-related configuration information into kernel
memory and starting several daemons. More specifically, the afsd
command performs the following actions:
¬∑ Sets a field in kernel memory that defines the machine‚Äôs cell
membership. Some Cache Manager-internal operations and system calls
consult this field to learn which cell to execute in. (The AFS
command interpreters refer to the /etc/openafs/ThisCell file
instead.) This information is transferred into the kernel from the
/etc/openafs/ThisCell file and cannot be changed until the afsd
program runs again.
¬∑ Places in kernel memory the names and Internet addresses of the
database server machines in the local cell and (optionally) foreign
cells. The appearance of a cell‚Äôs database server machines in this
list enables the Cache Manager to contact them and to access files
in the cell. Omission of a cell from this list, or incorrect
information about its database server machines, prevents the Cache
Manager from accessing files in it.
The list of database server machines is transferred into the kernel
from the /etc/openafs/CellServDB file. After initialization, use
the fs newcell command to change the kernel-resident list without
having to reboot.
¬∑ Mounts the root of the AFS filespace on a directory on the
machine‚Äôs local disk, according to either the first field in the
/etc/openafs/cacheinfo file (the default) or the afsd command‚Äôs
-mountdir argument. The conventional value is /afs.
¬∑ Determines which volume to mount at the root of the AFS file tree.
The default is the volume root.afs; use the -rootvol argument to
override it. Although the base (read/write) form of the volume name
is the appropriate value, the Cache Manager has a bias for
accessing the read-only version of the volume (by convention,
root.afs.readonly) if it is available.
¬∑ Configures the cache on disk (the default) or in machine memory if
the -memcache argument is provided. In the latter case, the afsd
program allocates space in machine memory for caching, and the
Cache Manager uses no disk space for caching even if the machine
has a disk.
¬∑ Defines the name of the local disk directory devoted to caching,
when the -memcache argument is not used. If necessary, the afsd
program creates the directory (its parent directory must already
exist). It does not remove the directory that formerly served this
function, if one exists.
The second field in the /etc/openafs/cacheinfo file is the source
for this name, and the standard value is the /usr/vice/cache
directory. Use the -cachedir argument to override the value in the
¬∑ Sets the size of the cache. The default source for the value is the
third field in the /etc/openafs/cacheinfo file, which specifies a
number of kilobytes.
For a memory cache, the following arguments to the afsd command
override the value in the cacheinfo file:
¬∑ The -blocks argument, to specify a different number of kilobyte
¬∑ The -dcache and -chunksize arguments together, to set both the
number of dcache entries and the chunk size (see below for
definition of these parameters). In this case, the afsd program
derives cache size by multiplying the two values. Using this
combination is not recommended, as it requires the issuer to
perform the calculation beforehand to determine the resulting
¬∑ The -dcache argument by itself. In this case, the afsd program
derives cache size by multiplying the value specified by the
-dcache argument by the default memory cache chunk size of
eight kilobytes. Using this argument is not recommended, as it
requires the issuer to perform the calculation beforehand to
determine the resulting cache size.
For satisfactory memory cache performance, the specified value
must leave enough memory free to accommodate all other
processes and commands that can run on the machine. If the
value exceeds the amount of memory available, the afsd program
exits without initializing the Cache Manager and produces the
following message on the standard output stream:
afsd: memCache allocation failure at <number> KB
where <number> is how many kilobytes were allocated just before
For a disk cache, use the -blocks argument to the afsd command
to override the value in the cacheinfo file. The value
specified in either way sets an absolute upper limit on cache
size; values provided for other arguments (such as -dcache and
-chunksize) never result in a larger cache. The afsd program
rejects any setting larger than 95% of the partition size, and
exits after generating an error message on the standard output
stream, because the cache implementation itself requires a
small amount of disk space and overfilling the partition can
cause the client machine to panic.
To change the size of a disk cache after initialization without
rebooting, use the fs setcachesize command; the setting
persists until the afsd command runs again or the fs
setcachesize command is reissued. The fs setcachesize command
does not work for memory caches.
¬∑ Sets the size of each cache chunk, and by implication the amount of
data that the Cache Manager requests at a time from the File Server
(how much data per fetch RPC, since AFS uses partial file
For a disk cache, a chunk is a Vn file and this parameter sets the
maximum size to which each one can expand; the default is 64 KB.
For a memory cache, each chunk is a collection of contiguous memory
blocks; the default is size is 8 KB.
To override the default chunk size for either type of cache, use
the -chunksize argument to provide an integer to be used as an
exponent of two; see the OPTIONS manpage for details. For a memory
cache, if total cache size divided by chunk size leaves a
remainder, the afsd program rounds down the number of dcache
entries, resulting in a slightly smaller cache.
¬∑ Sets the number of chunks in the cache. For a memory cache, the
number of chunks is equal to the cache size divided by the chunk
size. For a disk cache, the number of chunks (Vn files) is set to
the largest of the following unless the -files argument is used to
set the value explicitly:
¬∑ 1.5 times the result of dividing cache size by chunk size
(cachesize/chunksize * 1.5)
¬∑ The result of dividing cachesize by 10 KB (cachesize/10240)
¬∑ Sets the number of dcache entries allocated in machine memory for
storing information about the chunks in the cache.
For a disk cache, the /usr/vice/cache/CacheItems file contains one
entry for each Vn file. By default, one half the number of these
entries (but not more that 2,000) are duplicated as dcache entries
in machine memory for quicker access.
For a memory cache, there is no CacheItems file so all information
about cache chunks must be in memory as dcache entries. Thus,
there is no default number of dcache entries for a memory cache;
instead, the afsd program derives it by dividing the cache size by
the chunk size.
To set the number of dcache entries, use the -dcache argument; the
specified value can exceed the default limit of 2,000. Using this
argument is not recommended for either type of cache. Increasing
the number of dcache entries for a disk cache sometimes improves
performance (because more entries are retrieved from memory rather
than from disk), but only marginally. Using this argument for a
memory cache requires the issuer to calculate the cache size by
multiplying this value by the chunk size.
¬∑ Sets the number of stat entries available in machine memory for
caching status information about cached AFS files. The default is
300; use the -stat argument to override the default.
¬∑ Randomly selects a file server machine in the local cell as the
source for the correct time. Every five minutes thereafter, the
local clock is adjusted (if necessary) to match the file server
Use the -nosettime flag to prevent the afsd command from selecting
a time standard. This is recommended only on file server machines
that are also acting as clients. File server machines maintain the
correct time using the Network Time Protocol Daemon instead.
In addition to setting cache configuration parameters, the afsd program
starts the following daemons. (On most system types, these daemons
appear as nameless entries in the output of the UNIX ps command.)
¬∑ One callback daemon, which handles callbacks. It also responds to
the File Server‚Äôs periodic probes, which check that the client
machine is still alive.
¬∑ One maintenance daemon, which performs the following tasks:
¬∑ Garbage collects obsolete data (for example, expired tokens)
from kernel memory.
¬∑ Synchronizes files.
¬∑ Refreshes information from read-only volumes once per hour.
¬∑ Does delayed writes for NFS clients if the machine is running
the NFS/AFS Translator.
¬∑ One cache-truncation daemon, which flushes the cache when free
space is required, by writing cached data and status information to
the File Server.
¬∑ One server connection daemon, which sends a probe to the File
Server every few minutes to check that it is still accessible. It
also synchronizes the machine‚Äôs clock with the clock on a randomly-
chosen file server machine, unless the -nosettime flag is used.
There is always one server connection daemon.
¬∑ One or more background daemons that improve performance by pre-
fetching files and performing background (delayed) writes of saved
data into AFS.
The default number of background daemons is two, enough to service
at least five simultaneous users of the machine. To increase the
number, use the -daemons argument. A value greater than six is not
¬∑ On some system types, one Rx listener daemon, which listens for
¬∑ On some system types, one Rx event daemon, which reviews the Rx
system‚Äôs queue of tasks and performs them as appropriate. Most
items in the queue are retransmissions of failed packets.
¬∑ On machines that run AIX with virtual memory (VM) integration, one
or more VM daemons (sometimes called I/O daemons, which transfer
data between disk and machine memory. The number of them depends on
the setting of the -biods and -daemons arguments:
¬∑ If the -biods argument is used, it sets the number of VM
¬∑ If only the -daemons argument is used, the number of VM daemons
is twice the number of background daemons.
¬∑ If neither argument is used, there are five VM daemons.
This command does not use the syntax conventions of the AFS command
suites. Provide the command name and all option names in full.
Do not use the -shutdown parameter. It does not shutdown the Cache
Manager effectively. Instead, halt Cache Manager activity by using the
standard UNIX umount command to unmount the AFS root directory (by
convention, /afs). The machine must then be rebooted to reinitialize
the Cache Manager.
-blocks <blocks in cache>
Specifies the number of kilobyte blocks to be made available for
caching in the machine‚Äôs cache directory (for a disk cache) or
memory (for a memory cache), overriding the default defined in the
third field of the /etc/openafs/cacheinfo file. For a disk cache,
the value cannot exceed 95% of the space available in the cache
partition. If using a memory cache, do not combine this argument
with the -dcache argument, since doing so can possibly result in a
chunk size that is not an exponent of 2.
-files <files in cache>
Specifies the number of Vn files to create in the cache directory
for a disk cache, overriding the default that is calculated as
described in the DESCRIPTION manpage. Each Vn file accommodates a
chunk of data, and can grow to a maximum size of 64 KB by default.
Do not combine this argument with the -memcache argument.
-rootvol <name of AFS root volume>
Names the read/write volume corresponding to the root directory for
the AFS file tree (which is usually the /afs directory). This value
overrides the default of the root.afs volume.
-stat <number of stat entries>
Specifies the number of entries to allocate in the machine‚Äôs memory
for recording status information about the AFS files in the cache.
This value overrides the default of 300.
Initializes a memory cache rather than a disk cache. Do not combine
this flag with the -files argument.
-cachedir <cache directory>
Names the local disk directory to be used as the cache. This value
overrides the default defined in the second field of the
-mountdir <mount location>
Names the local disk directory on which to mount the root of the
AFS filespace. This value overrides the default defined in the
first field of the /etc/openafs/cacheinfo file. If a value other
than the /afs directory is used, the machine cannot access the
filespace of cells that do use that value.
-daemons <number of daemons to use>
Specifies the number of background daemons to run on the machine.
These daemons improve efficiency by doing prefetching and
background writing of saved data. This value overrides the default
of 2, which is adequate for a machine serving up to five users.
Values greater than 6 are not generally more effective than 6.
Note: On AIX machines with integrated virtual memory (VM), the
number of VM daemons is set to twice the value of this argument, if
it is provided and the -biods argument is not. If both arguments
are omitted, there are five VM daemons.
Prevents the Cache Manager from synchronizing its clock with the
clock on a server machine selected at random, by checking the time
on the server machine every five minutes. Use this flag only on a
machine that is already using another time synchronization protocol
(for example, a server machine that is running the runntp process).
Generates a detailed trace of the afsd program‚Äôs actions on the
standard output stream.
Initializes an additional daemon to execute AFS-specific system
calls on behalf of NFS client machines. Use this flag only if the
machine is an NFS/AFS translator machine serving users of NFS
client machines who execute AFS commands.
Generates a highly detailed trace of the afsd program‚Äôs actions on
the standard output stream. The information is useful mostly for
-chunksize <chunk size>
Sets the size of each cache chunk. The integer provided, which must
be from the range 0 to 30, is used as an exponent on the number 2.
It overrides the default of 16 for a disk cache (2^16 is 64 KB) and
13 for a memory cache (2^13 is 8 KB). A value of 0 or less, or
greater than 30, sets chunk size to the appropriate default. Values
less than 10 (which sets chunk size to a 1 KB) are not recommended.
Combining this argument with the -dcache argument is not
recommended because it requires that the issuer calculate the cache
size that results.
-dcache <number of dcache entries>
Sets the number of dcache entries in memory, which are used to
store information about cache chunks. For a disk cache, this
overrides the default, which is 50% of the number of Vn files
(cache chunks). For a memory cache, this argument effectively sets
the number of cache chunks, but its use is not recommended, because
it requires the issuer to calculate the resulting total cache size
(derived by multiplying this value by the chunk size). Do not
combine this argument with the -blocks argument, since doing so can
possibly result in a chunk size that is not an exponent of 2.
-volumes <number of volume entries>
Specifies the number of memory structures to allocate for storing
volume location information. The default value is 50.
-biods <number of I/O daemons>
Sets the number of VM daemons dedicated to performing I/O
operations on a machine running a version of AIX with virtual
memory (VM) integration. If both this argument and the -daemons
argument are omitted, the default is five. If this argument is
omitted but the -daemons argument is provided, the number of VM
daemons is set to twice the value of the -daemons argument.
-prealloc <number of preallocated blocks>
Specifies the number of pieces of memory to preallocate for the
Cache Manager‚Äôs internal use. The default initial value is 400, but
the Cache Manager dynamically allocates more memory as it needs it.
-confdir <configuration directory>
Names a directory other than the /etc/openafs directory from which
to fetch the cacheinfo, ThisCell, and CellServDB configuration
-logfile <log file location>
Is obsolete and has no real effect. It specifies an alternate file
in which to record a type of trace that the Cache Manager no longer
generates; the default value is /etc/openafs/AFSLog.
Has no effect on the operation of the Cache Manager. The behavior
it affected in previous versions of the Cache Manager, to perform
synchronous writes to the File Server, is now the default behavior.
To perform asynchronous writes in certain cases, use the fs
Shuts down the Cache Manager, but not in the most effective
possible way. Do not use this flag.
Activates the collection of Rx statistics and allocates memory for
their storage. For each connection with a specific UDP port on
another machine, a separate record is kept for each type of RPC
(FetchFile, GetStatus, and so on) sent or received. To display or
otherwise access the records, use the Rx Monitoring API.
Activates the collection of Rx statistics and allocates memory for
their storage. A separate record is kept for each type of RPC
(FetchFile, GetStatus, and so on) sent or received, aggregated over
all connections to other machines. To display or otherwise access
the records, use the Rx Monitoring API.
Prints the online help for this command. All other valid options
The afsd command is normally included in the machine‚Äôs AFS
initialization file, rather than typed at the command shell prompt. For
most disk caches, the appropriate form is
The following command is appropriate when enabling a machine to act as
an NFS/AFS Translator machine serving more than five users.
/etc/openafs/afsd -daemons 4 -rmtsys
The following command initializes a memory cache and sets chunk size to
16 KB (2^14).
/etc/openafs/afsd -memcache -chunksize 14
The issuer must be logged in as the local superuser root.
the afs_cache(5) manpage, the CellServDB(5) manpage, the cacheinfo(5)
IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.
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