Provided by: hdparm_9.65+ds-1build1_amd64 
NAME
hdparm - get/set SATA/IDE device parameters
SYNOPSIS
hdparm [options] [device ...]
DESCRIPTION
hdparm provides a command line interface to various kernel interfaces supported by the Linux
SATA/PATA/SAS "libata" subsystem and the older IDE driver subsystem. Many newer (2008 and later) USB
drive enclosures now also support "SAT" (SCSI-ATA Command Translation) and therefore may also work with
hdparm. E.g., recent WD "Passport" models and recent NexStar-3 enclosures. Some options may work
correctly only with the latest kernels.
OPTIONS
When no options are given, -acdgkmur is assumed. For "Get/set" options, a query without the optional
parameter (e.g., -d) will query (get) the device state, and with a parameter (e.g., -d0) will set the
device state.
-a Get/set sector count for filesystem (software) read-ahead. This is used to improve performance in
sequential reads of large files, by prefetching additional blocks in anticipation of them being
needed by the running task. Many IDE drives also have a separate built-in read-ahead function,
which augments this filesystem (software) read-ahead function.
-A Get/set the IDE drive's read-lookahead feature (usually ON by default). Usage: -A0 (disable) or
-A1 (enable).
-b Get/set bus state.
-B Get/set Advanced Power Management feature, if the drive supports it. A low value means aggressive
power management and a high value means better performance. Possible settings range from values 1
through 127 (which permit spin-down), and values 128 through 254 (which do not permit spin-down).
The highest degree of power management is attained with a setting of 1, and the highest I/O
performance with a setting of 254. A value of 255 tells hdparm to disable Advanced Power
Management altogether on the drive (not all drives support disabling it, but most do).
-c Get/set (E)IDE 32-bit I/O support. A numeric parameter can be used to enable/disable 32-bit I/O
support. Currently supported values include 0 to disable 32-bit I/O support, 1 to enable 32-bit
data transfers, and 3 to enable 32-bit data transfers with a special sync sequence required by
many chipsets. The value 3 works with nearly all 32-bit IDE chipsets, but incurs slightly more
overhead. Note that "32-bit" refers to data transfers across a PCI or VLB bus to the interface
card only; all (E)IDE drives still have only a 16-bit connection over the ribbon cable from the
interface card.
-C Check the current IDE power mode status, which will always be one of unknown (drive does not
support this command), active/idle (normal operation), standby (low power mode, drive has spun
down), or sleeping (lowest power mode, drive is completely shut down). The -S, -y, -Y, and -Z
options can be used to manipulate the IDE power modes.
-d Get/set the "using_dma" flag for this drive. This option now works with most combinations of
drives and PCI interfaces which support DMA and which are known to the kernel IDE driver. It is
also a good idea to use the appropriate -X option in combination with -d1 to ensure that the drive
itself is programmed for the correct DMA mode, although most BIOSs should do this for you at boot
time. Using DMA nearly always gives the best performance, with fast I/O throughput and low CPU
usage. But there are at least a few configurations of chipsets and drives for which DMA does not
make much of a difference, or may even slow things down (on really messed up hardware!). Your
mileage may vary.
--dco-freeze
DCO stands for Device Configuration Overlay, a way for vendors to selectively disable certain
features of a drive. The --dco-freeze option will freeze/lock the current drive configuration,
thereby preventing software (or malware) from changing any DCO settings until after the next
power-on reset.
--dco-identify
Query and dump information regarding drive configuration settings which can be disabled by the
vendor or OEM installer. These settings show capabilities of the drive which might be disabled by
the vendor for "enhanced compatibility". When disabled, they are otherwise hidden and will not
show in the -I identify output. For example, system vendors sometimes disable 48_bit addressing
on large drives, for compatibility (and loss of capacity) with a specific BIOS. In such cases,
--dco-identify will show that the drive is 48_bit capable, but -I will not show it, and nor will
the drive accept 48_bit commands.
--dco-restore
Reset all drive settings, features, and accessible capacities back to factory defaults and full
capabilities. This command will fail if DCO is frozen/locked, or if a -Np maximum size
restriction has also been set. This is EXTREMELY DANGEROUS and will very likely cause massive
loss of data. DO NOT USE THIS COMMAND.
--direct
Use the kernel's "O_DIRECT" flag when performing a -t timing test. This bypasses the page cache,
causing the reads to go directly from the drive into hdparm's buffers, using so-called "raw" I/O.
In many cases, this can produce results that appear much faster than the usual page cache method,
giving a better indication of raw device and driver performance.
--drq-hsm-error
VERY DANGEROUS, DON'T EVEN THINK ABOUT USING IT. This option causes hdparm to issue an IDENTIFY
command to the kernel, but incorrectly marked as a "non-data" command. This results in the drive
being left with its DataReQust(DRQ) line "stuck" high. This confuses the kernel drivers, and may
crash the system immediately with massive data loss. The option exists to help in testing and
fortifying the kernel against similar real-world drive malfunctions. VERY DANGEROUS, DO NOT USE!!
-D Enable/disable the on-drive defect management feature, whereby the drive firmware tries to
automatically manage defective sectors by relocating them to "spare" sectors reserved by the
factory for such. Control of this feature via the -D option is not supported for most modern
drives since ATA-4; thus this command may fail.
-E Set cd/dvd drive speed. This is NOT necessary for regular operation, as the drive will
automatically switch speeds on its own. But if you want to play with it, just supply a speed
number after the option, usually a number like 2 or 4. This can be useful in some cases, though,
to smooth out DVD video playback.
-f Sync and flush the buffer cache for the device on exit. This operation is also performed
internally as part of the -t and -T timings and other options.
--fallocate
This option currently works only on ext4 and xfs filesystem types. When used, this must be the
only option given. It requires two parameters: the desired file size in kibibytes (byte count
divided by 1024), followed by the pathname for the new file. It will create a new file of the
specified size, but without actually having to write any data to the file. This will normally
complete very quickly, and without thrashing the storage device.
E.g., create a 10 kibibyte file: hdparm --fallocate 10 temp_file
--fibmap
When used, this must be the only option given. It requires a file path as a parameter, and will
print out a list of the block extents (sector ranges) occupied by that file on disk. Sector
numbers are given as absolute LBA numbers, referenced from sector 0 of the physical device rather
than from the partition or filesystem. This information can then be used for a variety of
purposes, such as examining the degree of fragmentation of larger files, or determining
appropriate sectors to deliberately corrupt during fault-injection testing procedures.
This option uses the new FIEMAP (file extent map) ioctl() when available, and falls back to the
older FIBMAP (file block map) ioctl() otherwise. Note that FIBMAP suffers from a 32-bit block-
number interface, and thus not work beyond 8 TB or 16 TB. FIBMAP is also very slow, and does not
deal well with preallocated uncommitted extents in ext4/xfs filesystems, unless a sync() is done
before using this option.
--fwdownload
When used, this should be the only option given. It requires a file path immediately after the
option, indicating where the new drive firmware should be read from. The contents of this file
will be sent to the drive using the (S)ATA DOWNLOAD MICROCODE command, using either transfer
protocol 7 (entire file at once), or, if the drive supports it, transfer protocol 3 (segmented
download). This command is EXTREMELY DANGEROUS and could destroy both the drive and all data on
it. DO NOT USE THIS COMMAND. The --fwdownload-mode3 , --fwdownload-mode3-max , and --fwdownload-
mode7 variations on basic --fwdownload allow overriding automatic protocol detection in favour of
forcing hdparm to use a specific transfer protocol, for testing purposes only.
-F Flush the on-drive write cache buffer (older drives may not implement this).
-g Display the drive geometry (cylinders, heads, sectors), the size (in sectors) of the device, and
the starting offset (in sectors) of the device from the beginning of the drive.
-h Display terse usage information (help).
-H Read the temperature from some (mostly Hitachi) drives. Also reports if the temperature is within
operating condition range (this may not be reliable). Does not cause the drive to spin up if idle.
-i Display the identification info which the kernel drivers (IDE, libata) have stored from
boot/configuration time. This may differ from the current information obtainable directly from
the drive itself with the -I option. The data returned may or may not be current, depending on
activity since booting the system. For a more detailed interpretation of the identification info,
refer to AT Attachment Interface for Disk Drives, ANSI ASC X3T9.2 working draft, revision 4a,
April 19/93, and later editions.
--idle-immediate
Issue an ATA IDLE_IMMEDIATE command, to put the drive into a lower power state. Usually the
device remains spun-up.
--idle-unload
Issue an ATA IDLE_IMMEDIATE_WITH_UNLOAD command, to unload or park the heads and put the drive
into a lower power state. Usually the device remains spun-up.
-I Request identification info directly from the drive, which is displayed in a new expanded format
with considerably more detail than with the older -i option.
--Iraw <pathname>
This option dumps the drive's identify data in raw binary to the specified file.
--Istdin
This is a special variation on the -I option, which accepts a drive identification block as
standard input instead of using a /dev/hd* parameter. The format of this block must be exactly
the same as that found in the /proc/ide/*/hd*/identify "files", or that produced by the --Istdout
option described below. This variation is designed for use with collected "libraries" of drive
identification information, and can also be used on ATAPI drives which may give media errors with
the standard mechanism. When --Istdin is used, it must be the *only* parameter given. Note that
some information will be incomplete, as the drive LOG PAGES are unavailable when --Istdin is used.
--Istdout
This option dumps the drive's identify data in hex to stdout, in a format similar to that from
/proc/ide/*/identify, and suitable for later use with the --Istdin option.
-J Get/set the Western Digital (WD) Green Drive's "idle3" timeout value. This timeout controls how
often the drive parks its heads and enters a low power consumption state. The factory default is
eight (8) seconds, which is a very poor choice for use with Linux. Leaving it at the default will
result in hundreds of thousands of head load/unload cycles in a very short period of time. The
drive mechanism is only rated for 300,000 to 1,000,000 cycles, so leaving it at the default could
result in premature failure, not to mention the performance impact of the drive often having to
wake-up before doing routine I/O.
WD supply a WDIDLE3.EXE DOS utility for tweaking this setting, and you should use that program
instead of hdparm if at all possible. The reverse-engineered implementation in hdparm is not as
complete as the original official program, even though it does seem to work on at a least a few
drives. A full power cycle is required for any change in setting to take effect, regardless of
which program is used to tweak things.
A setting of 30 seconds is recommended for Linux use. Permitted values are from 8 to 12 seconds,
and from 30 to 300 seconds in 30-second increments. Specify a value of zero (0) to disable the WD
idle3 timer completely (NOT RECOMMENDED!).
-k Get/set the "keep_settings_over_reset" flag for the drive. When this flag is set, the drive will
preserve the -dmu settings over a soft reset, (as done during the error recovery sequence). This
option defaults to off, to prevent drive reset loops which could be caused by combinations of -dmu
settings. The -k option should therefore only be set after one has achieved confidence in correct
system operation with a chosen set of configuration settings. In practice, all that is typically
necessary to test a configuration (prior to using -k) is to verify that the drive can be
read/written, and that no error logs (kernel messages) are generated in the process (look in
/var/log/messages on most systems).
-K Set the drive's "keep_features_over_reset" flag. Setting this enables the drive to retain the
settings for -APSWXZ over a soft reset (as done during the error recovery sequence). Not all
drives support this feature.
-L Set the drive's doorlock flag. Setting this to 1 will lock the door mechanism of some removable
hard drives (e.g., Syquest, ZIP, Jazz..), and setting it to 0 will unlock the door mechanism.
Normally, Linux maintains the door locking mechanism automatically, depending on drive usage
(locked whenever a filesystem is mounted). But on system shutdown, this can be a nuisance if the
root partition is on a removable disk, since the root partition is left mounted (read-only) after
shutdown. So, by using this command to unlock the door after the root filesystem is remounted
read-only, one can then remove the cartridge from the drive after shutdown.
-m Get/set sector count for multiple sector I/O on the drive. A setting of 0 disables this feature.
Multiple sector mode (aka IDE Block Mode), is a feature of most modern IDE hard drives, permitting
the transfer of multiple sectors per I/O interrupt, rather than the usual one sector per
interrupt. When this feature is enabled, it typically reduces operating system overhead for disk
I/O by 30–50%. On many systems, it also provides increased data throughput of anywhere from 5% to
50%. Some drives, however (most notably the WD Caviar series), seem to run slower with multiple
mode enabled. Your mileage may vary. Most drives support the minimum settings of 2, 4, 8, or 16
(sectors). Larger settings may also be possible, depending on the drive. A setting of 16 or 32
seems optimal on many systems. Western Digital recommends lower settings of 4 to 8 on many of
their drives, due tiny (32 KiB) drive buffers and non-optimized buffering algorithms. The -i
option can be used to find the maximum setting supported by an installed drive (look for
MaxMultSect in the output). Some drives claim to support multiple mode, but lose data at some
settings. Under rare circumstances, such failures can result in massive filesystem corruption.
--make-bad-sector
Deliberately create a bad sector (aka. "media error") on the disk. EXCEPTIONALLY DANGEROUS. DO
NOT USE THIS OPTION!! This can be useful for testing of device/RAID error recovery mechanisms.
The sector number is given as a (base10) parameter after the option. Depending on the device,
hdparm will choose one of two possible ATA commands for corrupting the sector. The WRITE_LONG
works on most drives, but only up to the 28-bit sector boundary. Some very recent drives (2008)
may support the new WRITE_UNCORRECTABLE_EXT command, which works for any LBA48 sector. If
available, hdparm will use that in preference to WRITE_LONG. The WRITE_UNCORRECTABLE_EXT command
itself presents a choice of how the new bad sector should behave. By default, it will look like
any other bad sector, and the drive may take some time to retry and fail on subsequent READs of
the sector. However, if a single letter f is prepended immediately in front of the first digit of
the sector number parameter, then hdparm will issue a "flagged" WRITE_UNCORRECTABLE_EXT, which
causes the drive to merely flag the sector as bad (rather than genuinely corrupt it), and
subsequent READs of the sector will fail immediately (rather than after several retries). Note
also that the --repair-sector option can be used to restore (any) bad sectors when they are no
longer needed, including sectors that were genuinely bad (the drive will likely remap those to a
fresh area on the media).
-M Get/set Automatic Acoustic Management (AAM) setting. Most modern harddisk drives have the ability
to speed down the head movements to reduce their noise output. The possible values are between 0
and 254. 128 is the most quiet (and therefore slowest) setting and 254 the fastest (and loudest).
Some drives have only two levels (quiet / fast), while others may have different levels between
128 and 254. At the moment, most drives only support 3 options, off, quiet, and fast. These have
been assigned the values 0, 128, and 254 at present, respectively, but integer space has been
incorporated for future expansion, should this change.
-n Get or set the "ignore_write_errors" flag in the driver. Do NOT play with this without grokking
the driver source code first.
-N Get/set max visible number of sectors, also known as the Host Protected Area setting. Without a
parameter, -N displays the current setting, which is reported as two values: the first gives the
current max sectors setting, and the second shows the native (real) hardware limit for the disk.
The difference between these two values indicates how many sectors of the disk are currently
hidden from the operating system, in the form of a Host Protected Area (HPA). This area is often
used by computer makers to hold diagnostic software, and/or a copy of the originally provided
operating system for recovery purposes. Another possible use is to hide the true capacity of a
very large disk from a BIOS/system that cannot normally cope with drives of that size (e.g., most
current {2010} BIOSs cannot deal with drives larger than 2 TB, so an HPA could be used to cause a
3 TB drive to report itself as a 2 TB drive). To change the current max (VERY DANGEROUS, DATA
LOSS IS EXTREMELY LIKELY), a new value should be provided (in base10) immediately following the -N
option. This value is specified as a count of sectors, rather than the "max sector address" of
the drive. Drives have the concept of a temporary (volatile) setting which is lost on the next
hardware reset, as well as a more permanent (non-volatile) value which survives resets and power
cycles. By default, -N affects only the temporary (volatile) setting. To change the permanent
(non-volatile) value, prepend a leading p character immediately before the first digit of the
value. Drives are supposed to allow only a single permanent change per session. A hardware reset
(or power cycle) is required before another permanent -N operation can succeed. Note that any
attempt to set this value may fail if the disk is being accessed by other software at the same
time. This is because setting the value requires a pair of back-to-back drive commands, but there
is no way to prevent some other command from being inserted between them by the kernel. So if it
fails initially, just try again. Kernel support for -N is buggy for many adapter types across
many kernel versions, in that an incorrect (too small) max size value is sometimes reported. As
of the 2.6.27 kernel, this does finally seem to be working on most hardware.
--offset
Offsets to given number of GiB (1024*1024*1024) when performing -t timings of device reads. Speed
changes (about twice) along many mechanical drives. Usually the maximum is at the beginning, but
not always. Solid-state drives (SSDs) should show similar timings regardless of offset.
-p Attempt to reprogram the IDE interface chipset for the specified PIO mode, or attempt to auto-tune
for the "best" PIO mode supported by the drive. This feature is supported in the kernel for only
a few "known" chipsets, and even then the support is iffy at best. Some IDE chipsets are unable
to alter the PIO mode for a single drive, in which case this option may cause the PIO mode for
both drives to be set. Many IDE chipsets support either fewer or more than the standard six (0 to
5) PIO modes, so the exact speed setting that is actually implemented will vary by chipset/driver
sophistication. Use with extreme caution! This feature includes zero protection for the unwary,
and an unsuccessful outcome may result in severe filesystem corruption!
-P Set the maximum sector count for the drive's internal prefetch mechanism. Not all drives support
this feature, and it was dropped from the official spec as of ATA-4.
--prefer-ata12
When using the SAT (SCSI ATA Translation) protocol, hdparm normally prefers to use the 16-byte
command format whenever possible. But some USB drive enclosures don't work correctly with 16-byte
commands. This option can be used to force use of the smaller 12-byte command format with such
drives. hdparm will still revert to 16-byte commands for things that cannot be done with the
12-byte format (e.g., sector accesses beyond 28-bits).
-q Handle the next option quietly, suppressing normal output (but not error messages). This is
useful for reducing screen clutter when running from system startup scripts. Not applicable to
the -i or -v or -t or -T options.
-Q Get or set the device's command queue_depth, if supported by the hardware. This only works with
2.6.xx (or later) kernels, and only with device and driver combinations which support changing the
queue_depth. For SATA disks, this is the Native Command Queuing (NCQ) queue depth.
-r Get/set read-only flag for the device. When set, Linux disallows write operations on the device.
-R Get/set Write-Read-Verify feature, if the drive supports it. Usage: -R0 (disable) or -R1
(enable). This feature is intended to have the drive firmware automatically read-back any data
that is written by software, to verify that the data was successfully written. This is generally
overkill, and can slow down disk writes by as much as a factor of two (or more).
--read-sector
Reads from the specified sector number, and dumps the contents in hex to standard output. The
sector number must be given (base10) after this option. hdparm will issue a low-level read
(completely bypassing the usual block layer read/write mechanisms) for the specified sector. This
can be used to definitively check whether a given sector is bad (media error) or not (doing so
through the usual mechanisms can sometimes give false positives).
--repair-sector
This is an alias for the --write-sector option. VERY DANGEROUS.
-s Enable/disable the power-on in standby feature, if supported by the drive. VERY DANGEROUS. Do
not use unless you are absolutely certain that both the system BIOS (or firmware) and the
operating system kernel (Linux >= 2.6.22) support probing for drives that use this feature. When
enabled, the drive is powered-up in the standby mode to allow the controller to sequence the spin-
up of devices, reducing the instantaneous current draw burden when many drives share a power
supply. Primarily for use in large RAID setups. This feature is usually disabled and the drive
is powered-up in the active mode (see -C above). Note that a drive may also allow enabling this
feature by a jumper. Some SATA drives support the control of this feature by pin 11 of the SATA
power connector. In these cases, this command may be unsupported or may have no effect.
-S Put the drive into idle (low-power) mode, and also set the standby (spindown) timeout for the
drive. This timeout value is used by the drive to determine how long to wait (with no disk
activity) before turning off the spindle motor to save power. Under such circumstances, the drive
may take as long as 30 seconds to respond to a subsequent disk access, though most drives are much
quicker. The encoding of the timeout value is somewhat peculiar. A value of zero means "timeouts
are disabled": the device will not automatically enter standby mode. Values from 1 to 240 specify
multiples of 5 seconds, yielding timeouts from 5 seconds to 20 minutes. Values from 241 to 251
specify from 1 to 11 units of 30 minutes, yielding timeouts from 30 minutes to 5.5 hours. A value
of 252 signifies a timeout of 21 minutes. A value of 253 sets a vendor-defined timeout period
between 8 and 12 hours, and the value 254 is reserved. 255 is interpreted as 21 minutes plus 15
seconds. Note that some older drives may have very different interpretations of these values.
--set-sector-size
For drives which support reconfiguring of the Logical Sector Size, this flag can be used to
specify the new desired sector size in bytes. VERY DANGEROUS. This most likely will scramble all
data on the drive. The specified size must be one of 512, 520, 528, 4096, 4160, or 4224. Very
few drives support values other than 512 and 4096. Eg. hdparm --set-sector-size 4096 /dev/sdb
-t Perform timings of device reads for benchmark and comparison purposes. For meaningful results,
this operation should be repeated 2–3 times on an otherwise inactive system (no other active
processes) with at least a couple of megabytes of free memory. This displays the speed of reading
through the buffer cache to the disk without any prior caching of data. This measurement is an
indication of how fast the drive can sustain sequential data reads under Linux, without any
filesystem overhead. To ensure accurate measurements, the buffer cache is flushed during the
processing of -t using the BLKFLSBUF ioctl.
-T Perform timings of cache reads for benchmark and comparison purposes. For meaningful results,
this operation should be repeated 2–3 times on an otherwise inactive system (no other active
processes) with at least a couple of megabytes of free memory. This displays the speed of reading
directly from the Linux buffer cache without disk access. This measurement is essentially an
indication of the throughput of the processor, cache, and memory of the system under test.
--trim-sector-ranges
For Solid State Drives (SSDs). EXCEPTIONALLY DANGEROUS. DO NOT USE THIS OPTION!! Tells the drive
firmware to discard unneeded data sectors, destroying any data that may have been present within
them. This makes those sectors available for immediate use by the firmware's garbage collection
mechanism, to improve scheduling for wear-leveling of the flash media. This option expects one or
more sector range pairs immediately after the option: an LBA starting address, a colon, and a
sector count (max 65535), with no intervening spaces. EXCEPTIONALLY DANGEROUS. DO NOT USE THIS
OPTION!!
E.g., hdparm --trim-sector-ranges 1000:4 7894:16 /dev/sdz
--trim-sector-ranges-stdin
Identical to --trim-sector-ranges above, except the list of lba:count pairs is read from stdin
rather than being specified on the command line. This can be used to avoid problems with
excessively long command lines. It also permits batching of many more sector ranges into single
commands to the drive, up to the currently configured transfer limit (max_sectors_kb).
-u Get/set the interrupt-unmask flag for the drive. A setting of 1 permits the driver to unmask
other interrupts during processing of a disk interrupt, which greatly improves Linux's
responsiveness and eliminates "serial port overrun" errors. Use this feature with caution: some
drive/controller combinations do not tolerate the increased I/O latencies possible when this
feature is enabled, resulting in massive filesystem corruption. In particular, CMD-640B and
RZ1000 (E)IDE interfaces can be unreliable (due to a hardware flaw) when this option is used with
kernel versions earlier than 2.0.13. Disabling the IDE prefetch feature of these interfaces
(usually a BIOS/CMOS setting) provides a safe fix for the problem for use with earlier kernels.
-v Display some basic settings, similar to -acdgkmur for IDE. This is also the default behaviour
when no options are specified.
-V Display program version and exit immediately.
--verbose
Display extra diagnostics from some commands.
-w Perform a device reset (DANGEROUS). Do NOT use this option. It exists for unlikely situations
where a reboot might otherwise be required to get a confused drive back into a useable state.
--write-sector
Writes zeros to the specified sector number. VERY DANGEROUS. The sector number must be given
(base10) after this option. hdparm will issue a low-level write (completely bypassing the usual
block layer read/write mechanisms) to the specified sector. This can be used to force a drive to
repair a bad sector (media error).
-W Get/set the IDE/SATA drive's write-caching feature.
-X Set the IDE transfer mode for (E)IDE/ATA drives. This is typically used in combination with -d1
when enabling DMA to/from a drive on a supported interface chipset, where -X mdma2 is used to
select multiword DMA mode2 transfers and -X sdma1 is used to select simple mode 1 DMA transfers.
With systems which support UltraDMA burst timings, -X udma2 is used to select UltraDMA mode2
transfers (you'll need to prepare the chipset for UltraDMA beforehand). Apart from that, use of
this option is seldom necessary since most/all modern IDE drives default to their fastest PIO
transfer mode at power-on. Fiddling with this can be both needless and risky. On drives which
support alternate transfer modes, -X can be used to switch the mode of the drive only. Prior to
changing the transfer mode, the IDE interface should be jumpered or programmed (see -p option) for
the new mode setting to prevent loss and/or corruption of data. Use this with extreme caution!
For the PIO (Programmed Input/Output) transfer modes used by Linux, this value is simply the
desired PIO mode number plus 8. Thus, a value of 09 sets PIO mode1, 10 enables PIO mode2, and 11
selects PIO mode3. Setting 00 restores the drive's "default" PIO mode, and 01 disables IORDY.
For multiword DMA, the value used is the desired DMA mode number plus 32. for UltraDMA, the value
is the desired UltraDMA mode number plus 64.
-y Force an IDE drive to immediately enter the low power consumption standby mode, usually causing it
to spin down. The current power mode status can be checked using the -C option.
-Y Force an IDE drive to immediately enter the lowest power consumption sleep mode, causing it to
shut down completely. A hard or soft reset is required before the drive can be accessed again
(the Linux IDE driver will automatically handle issuing a reset if/when needed). The current
power mode status can be checked using the -C option.
-z Force a kernel re-read of the partition table of the specified device(s).
-Z Disable the automatic power-saving function of certain Seagate drives (ST3xxx models?), to prevent
them from idling/spinning-down at inconvenient times.
ATA Security Feature Set
These switches are DANGEROUS to experiment with, and might not work with some kernels. USE AT YOUR OWN
RISK.
--security-help
Display terse usage info for all of the --security-* options.
--security-freeze
Freeze the drive's security settings. The drive does not accept any security commands until next
power-on reset. Use this function in combination with --security-unlock to protect drive from any
attempt to set a new password. Can be used standalone, too. No other options are permitted on the
command line with this one.
--security-prompt-for-password
Prompt for the --security PWD rather than getting from the command line args. This avoids having
passwords show up in shell history or in /proc/self/cmdline during execution.
--security-unlock PWD
Unlock the drive, using password PWD. Password is given as an ASCII string and is padded with
NULs to reach 32 bytes. The applicable drive password is selected with the --user-master switch
(default is "user" password). No other options are permitted on the command line with this one.
--security-set-pass PWD
Lock the drive, using password PWD (Set Password) (DANGEROUS). Password is given as an ASCII
string and is padded with NULs to reach 32 bytes. Use the special password NULL to set an empty
password. The applicable drive password is selected with the --user-master switch (default is
"user" password) and the applicable security mode with the --security-mode switch. No other
options are permitted on the command line with this one.
--security-disable PWD
Disable drive locking, using password PWD. Password is given as an ASCII string and is padded
with NULs to reach 32 bytes. The applicable drive password is selected with the --user-master
switch (default is "user" password). No other options are permitted on the command line with this
one.
--security-erase PWD
Erase (locked) drive, using password PWD (DANGEROUS). Password is given as an ASCII string and is
padded with NULs to reach 32 bytes. Use the special password NULL to represent an empty password.
The applicable drive password is selected with the --user-master switch (default is "user"
password). No other options are permitted on the command line with this one.
--security-erase-enhanced PWD
Enhanced erase (locked) drive, using password PWD (DANGEROUS). Password is given as an ASCII
string and is padded with NULs to reach 32 bytes. The applicable drive password is selected with
the --user-master switch (default is "user" password). No other options are permitted on the
command line with this one.
--user-master USER
Specifies which password (user/master) to select. Defaults to user password. Only useful in
combination with --security-unlock, --security-set-pass, --security-disable, --security-erase or
--security-erase-enhanced.
u user password
m master password
--security-mode MODE
Specifies which security mode (high/maximum) to set. Defaults to high. Only useful in
combination with --security-set-pass.
h high security
m maximum security
THIS FEATURE IS EXPERIMENTAL AND NOT WELL TESTED. USE AT YOUR OWN RISK.
FILES
/etc/hdparm.conf
BUGS
As noted above, the -m sectcount and -u 1 options should be used with caution at first, preferably on a
read-only filesystem. Most drives work well with these features, but a few drive/controller combinations
are not 100% compatible. Filesystem corruption may result. Backup everything before experimenting!
Some options (e.g., -r for SCSI) may not work with old kernels as necessary ioctl()'s were not supported.
Although this utility is intended primarily for use with SATA/IDE hard disk devices, several of the
options are also valid (and permitted) for use with SCSI hard disk devices and MFM/RLL hard disks with XT
interfaces.
The Linux kernel up until 2.6.12 (and probably later) doesn't handle the security unlock and disable
commands gracefully and will segfault and in some cases even panic. The security commands however might
indeed have been executed by the drive. This poor kernel behaviour makes the PIO data security commands
rather useless at the moment.
Note that the "security erase" and "security disable" commands have been implemented as two consecutive
PIO data commands and will not succeed on a locked drive because the second command will not be issued
after the segfault. See the code for hints how patch it to work around this problem. Despite the
segfault it is often still possible to run two instances of hdparm consecutively and issue the two
necessary commands that way.
AUTHOR
hdparm has been written by Mark Lord <mlord@pobox.com>, the original primary developer and maintainer of the (E)IDE driver for Linux, and current contributor to the libata subsystem, along with suggestions and patches from many netfolk. The disable Seagate auto-powersaving code is courtesy of Tomi Leppikangas(tomilepp@paju.oulu.fi). Security freeze command by Benjamin Benz, 2005. PIO data out security commands by Leonard den Ottolander, 2005. Some other parts by Benjamin Benz and others.
SEE ALSO
http://www.t13.org/ Technical Committee T13 AT Attachment (ATA/ATAPI) Interface. http://www.serialata.org/ Serial ATA International Organization. http://www.compactflash.org/ CompactFlash Association.