Linux命令：hdparm

功能说明：显示与设定硬盘的参数。 

语　　法：hdparm [-CfghiIqtTvyYZ][-a <快取分区>][-A <0或1>][-c ][-d <0或1>][-k <0或1>][-K <0或1>][-m <分区数>][-n <0或1>][-p ][-P <分区数>][-r <0或1>][-S <时间>][-u <0或1>][-W <0或1>][-X <传输模式>][设备] 

补充说明：hdparm可检测，显示与设定IDE或SCSI硬盘的参数。 

参　　数： -a<快取分区> 设定读取文件时，预先存入块区的分区数，若不加上<快取分区>选项，则显示目前的设定。 -A<0或1> 启动或关闭读取文件时的快取功能。 -c 设定IDE32位I/O模式。 -C 检测IDE硬盘的电源管理模式。 -d<0或1> 设定磁盘的DMA模式。 -f 将内存缓冲区的数据写入硬盘，并清楚缓冲区。 -g 显示硬盘的磁轨，磁头，磁区等参数。 -h 显示帮助。 -i 显示硬盘的硬件规格信息，这些信息是在开机时由硬盘本身所提供。 -I 直接读取硬盘所提供的硬件规格信息。 -k<0或1> 重设硬盘时，保留-dmu参数的设定。 -K<0或1> 重设硬盘时，保留-APSWXZ参数的设定。 -m<磁区数> 设定硬盘多重分区存取的分区数。 -n<0或1> 忽略硬盘写入时所发生的错误。 -p 设定硬盘的PIO模式。 -P<磁区数> 设定硬盘内部快取的分区数。 -q 在执行後续的参数时，不在屏幕上显示任何信息。 -r<0或1> 设定硬盘的读写模式。 -S<时间> 设定硬盘进入省电模式前的等待时间。 -t 评估硬盘的读取效率。 -T 平谷硬盘快取的读取效率。 -u<0或1> 在硬盘存取时，允许其他中断要求同时执行。 -v 显示硬盘的相关设定。 -W<0或1> 设定硬盘的写入快取。 -X<传输模式> 设定硬盘的传输模式。 -y 使IDE硬盘进入省电模式。 -Y 使IDE硬盘进入睡眠模式。 -Z 关闭某些Seagate硬盘的自动省电功能。 

英文版本，欢迎翻译：

NAME hdparm - get/set hard disk parameters

SYNOPSIS hdparm [ -a [sectcount] ] [ -A [0|1] ] [ -c [chipset_mode] ] [ -C ] [ -d [0|1] ] [ -f ] [ -g ] [ -i ] [ -k [0|1] ] [ -K [0|1] ] [ -L [0|1] ] [ -m [sectcount] ] [ -p [0|1|2|3|4|5] ] [ -P [sectcount] ] [ -q ] [ -r [0|1] ] [ -S [timeout] ] [ -T ] [ -t ] [ -u [0|1] ] [ -v ] [ -W [0|1] ] [ -X [xfermode] ] [ -y ] [ -Y ] [ -Z ] [device] ..

DESCRIPTION hdparm provides a command line interface to various hard disk ioctls supported by the stock Linux IDE/ST-506 device driver. This utility requires Linux kernel version 1.2.13 or later. Some options may not work correctly with earlier kernels. In addition, several options are supported only for kernels which include the new (E)IDE device driver, such as version 2.0.10 or later. These options are unavail? able when hdparm is compiled on systems with older kernel files in /usr/include/linux.

OPTIONS When no flags are given, -acdgkmnru is assumed (except when a given device is SCSI or an old XT-type MFM/RLL, in which cases -gr and -adgr are the defaults, respectively).

-a Get/set sector count for filesystem read-ahead. This is used to improve performance in sequen? tial reads of large files, by prefetching additional blocks in anticipation of them being needed by the running task. In the current kernel version (2.0.10) this has a default setting of 8 sec? tors (4KB). This value seems good for most purposes, but in a system where most file accesses are random seeks, a smaller setting might provide better performance. Also, many IDE drives also have a separate built-in read-ahead function, which alleviates the need for a filesystem read- ahead in many situations.

-A Disable/enable the IDE drives read-lookahead feature (usually ON by default).

-c Query/enable (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 sup? port 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 flags can be used to manipulate the IDE power modes.

-d Disable/enable the "using_dma" flag for this drive. This option only works with a few combina? tions of drives and interfaces which support DMA and which are known to the IDE driver (and with all supported XT interfaces). In particular, the Intel Triton chipset is supported for bus-mas? tered DMA operation with many drives (experimental). It is also a good idea to use the -X34 option in combination with -d1 to ensure that the drive itself is programmed for multiword DMA mode2. Using DMA does not necessarily provide any improvement in throughput or system perfor? mance, but many folks swear by it. Your mileage may vary.

-E Set cdrom 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.

-f Sync and flush the buffer cache for the device on exit. This operation is also performed as part of the -t and -T timings.

-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).

-i Display the identification info that was obtained from the drive at boot time, if available. This is a feature of modern IDE drives, and may not be supported by older devices. The data returned may or may not be current, depending on activity since booting the system. However, the current multiple sector mode count is always shown. 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).

-I Request identification info directly from the drive, which is displayed in its raw form with no endian changes or corrections. Otherwise similar to the -i option.

-k Get/set the keep_settings_over_reset flag for the drive. When this flag is set, the driver will preserve the -dmu options over a soft reset, (as done during the error recovery sequence). This flag defaults to off, to prevent drive reset loops which could be caused by combinations of -dmu settings. The -k flag 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/adm/messages on most systems).

-K Set the drives keep_features_over_reset flag. Setting this enables the drive to retain the set? tings 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 will lock the door mechanism of some removeable hard drives (eg. Syquest, ZIP, Jazz..), and setting it to 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 removeable disk, since the root partition is left mounted (read-only) after shutdown. So, by using this command to unlock the door -b 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, permit? ting 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 multi? ple 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 flag can be used to find the maximum setting supported by an installed drive (look for MaxMult? Sect 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.

-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 flag 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.

-q Handle the next flag quietly, supressing normal output. This is useful for reducing screen clut? ter when running from /etc/rc.c/rc.local. Not applicable to the -i or -v or -t or -T flags.

-r Get/set read-only flag for device. When set, write operations are not permitted on the device.

-R Register an IDE interface. Dangerous. See the -U option for more information.

-S Set the standby (spindown) timeout for the drive. This 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 "off". Values from 1 to 240 specify multiples of 5 seconds, for timeouts from 5 seconds to 20 minutes. Values from 241 to 251 specify from 1 to 11 units of 30 minutes, for timeouts from 30 minutes to 5.5 hours. A value of 252 signifies a timeout of 21 minutes, 253 sets a vendor-defined timeout, and 255 is interpreted as 21 minutes plus 15 seconds.

-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 pro? cesses) 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. If the -t flag is also specified, then a correction factor based on the outcome of -T will be incor? porated into the result reported for the -t operation.

-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 pro? cesses) 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 measurments, the buffer cache is flushed during the pro? cessing of -t using the BLKFLSBUF ioctl. If the -T flag is also specified, then a correction factor based on the outcome of -T will be incorporated into the result reported for the -t opera? tion.

-u Get/set 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/con? troller 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 ver? sions 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.

-U Un-register an IDE interface. Dangerous. The companion for the -R option. Intended for use with hardware made specifically for hot-swapping (very rare!). Use with knowledge and extreme caution as this can easily hang or damage your system. The hdparm source distribution includes a contrib directory with some user-donated scripts for hot-swapping on the UltraBay of a ThinkPad 600E. Use at your own risk.

-v Display all settings, except -i (same as -acdgkmnru for IDE, -gr for SCSI or -adgr for XT). This is also the default behaviour when no flags are specified.

-W Disable/enable the IDE drives write-caching feature (usually OFF by default).

-X Set the IDE transfer mode for newer (E)IDE/ATA2 drives. This is typically used in combination with -d1 when enabling DMA to/from a drive on a supported interface chipset (such as the Intel 430FX Triton), where -X34 is used to select multiword DMA mode2 transfers. With systems which support UltraDMA burst timings, -X66 is used to select UltraDMA mode2 transfers (youll need to prepare the chipset for UltraDMA beforehand). Apart from that, use of this flag is seldom neces? sary 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 flag) for the new mode setting to pre? vent 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 flag.

-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 flag.

-Z Disable the automatic power-saving function of certain Seagate drives (ST3xxx models?), to pre? vent them from idling/spinning-down at inconvenient times.

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 combina? tions are not 100% compatible. Filesystem corruption may result. Backup everything before experiment? ing!

Some options (eg. -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 (E)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.

AUTHOR hdparm has been written by Mark Lord <[email protected]>, the primary developer and maintainer of the (E)IDE driver for Linux, with suggestions from many netfolk.

The disable Seagate auto-powersaving code is courtesy of Tomi Leppikangas([email protected]).

SEE ALSO AT Attachment Interface for Disk Drives, ANSI ASC X3T9.2 working draft, revision 4a, April 19, 1993.

AT Attachment Interface with Extensions (ATA-2), ANSI ASC X3T9.2 working draft, revision 2f, July 26, 1994.

Western Digital Enhanced IDE Implementation Guide, by Western Digital Corporation, revision 5.0, Novem? ber 10, 1993.

Enhanced Disk Drive Specification, by Phoenix Technologies Ltd., version 1.0, January 25, 1994.

Version 3.9 February 2000 1

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