Difference between revisions of "Hardware"

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498 bytes added ,  19:31, 22 April 2017
Add section on electrical power
(Add section on BIOS / CPU microcode updates)
(Add section on electrical power)
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The ATA TRIM command in SATA 3.0 and earlier is a non-queued command. Issuing a TRIM command on a SATA drive conforming to SATA 3.0 or earlier will cause the drive to drain its IO queue and stop servicing requests until it finishes, which hurts performance. SATA 3.1 removed this limitation, but very few SATA drives on the market are conformant to SATA 3.1 and it is difficult to distinguish them from SATA 3.0 drives. At the same time, SCSI UNMAP has no such problems.
The ATA TRIM command in SATA 3.0 and earlier is a non-queued command. Issuing a TRIM command on a SATA drive conforming to SATA 3.0 or earlier will cause the drive to drain its IO queue and stop servicing requests until it finishes, which hurts performance. SATA 3.1 removed this limitation, but very few SATA drives on the market are conformant to SATA 3.1 and it is difficult to distinguish them from SATA 3.0 drives. At the same time, SCSI UNMAP has no such problems.
= Power =
Ensuring that computers are properly grounded is highly recommended. There have been cases in user homes where machines experienced random failures when plugged into power receptacles that had open grounds (i.e. no ground wire at all). This can cause random failures on any computer system, whether it uses ZFS or not.
Power should also have be relatively stable such that large dips in voltages from brownouts are preferable avoided through the use of UPS units or line conditioners.
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