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On some drives, reading the drive temperature resets the drive's spin-down timer. If the drive temperature is read too often, affected drives will never spin down. Add this information as usage note to the driver documentation. Reported-by: Peter Sulyok <peter@sulyok.net> Cc: Peter Sulyok <peter@sulyok.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
71 lines
2.4 KiB
ReStructuredText
71 lines
2.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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Kernel driver drivetemp
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=======================
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References
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----------
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ANS T13/1699-D
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Information technology - AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)
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ANS Project T10/BSR INCITS 513
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Information technology - SCSI Primary Commands - 4 (SPC-4)
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ANS Project INCITS 557
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Information technology - SCSI / ATA Translation - 5 (SAT-5)
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Description
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-----------
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This driver supports reporting the temperature of disk and solid state
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drives with temperature sensors.
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If supported, it uses the ATA SCT Command Transport feature to read
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the current drive temperature and, if available, temperature limits
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as well as historic minimum and maximum temperatures. If SCT Command
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Transport is not supported, the driver uses SMART attributes to read
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the drive temperature.
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Usage Note
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----------
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Reading the drive temperature may reset the spin down timer on some drives.
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This has been observed with WD120EFAX drives, but may be seen with other
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drives as well. The same behavior is observed if the 'hdtemp' or 'smartd'
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tools are used to access the drive.
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With the WD120EFAX drive, reading the drive temperature using the drivetemp
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driver is still possible _after_ it transitioned to standby mode, and
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reading the drive temperature in this mode will not cause the drive to
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change its mode (meaning the drive will not spin up). It is unknown if other
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drives experience similar behavior.
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A known workaround for WD120EFAX drives is to read the drive temperature at
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intervals larger than twice the spin-down time. Otherwise affected drives
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will never spin down.
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Sysfs entries
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-------------
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Only the temp1_input attribute is always available. Other attributes are
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available only if reported by the drive. All temperatures are reported in
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milli-degrees Celsius.
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======================= =====================================================
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temp1_input Current drive temperature
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temp1_lcrit Minimum temperature limit. Operating the device below
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this temperature may cause physical damage to the
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device.
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temp1_min Minimum recommended continuous operating limit
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temp1_max Maximum recommended continuous operating temperature
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temp1_crit Maximum temperature limit. Operating the device above
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this temperature may cause physical damage to the
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device.
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temp1_lowest Minimum temperature seen this power cycle
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temp1_highest Maximum temperature seen this power cycle
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======================= =====================================================
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