hdparm(8)
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 drives 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 kernels "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 kilo-bytes
(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 10KByte 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 fragmenation 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 8TB or 16TB.
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.
--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.
--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 drives "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 drives 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 (32kB) 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 (eg. most current {2010} BIOSs cannot deal
with drives larger than 2TB, so an HPA could be used to cause a
3TB drive to report itself as a 2TB 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 drives 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.
-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 Linuxs
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 drives 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 (youll 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 drives "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 drives 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-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) doesnt 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.
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