Date: Fri, 4 Oct 2013 19:39:01 -0700 From: Nuno Subtil <subtil@gmail.com> To: freebsd-hackers@freebsd.org Subject: Staggered wake-up from standby for SATA disks Message-ID: <CALdXDfcH%2B0-mo_beqQJWq0cy8H1Cs8Qeq1AtxjAP1SrEAM72UA@mail.gmail.com>
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Greetings, I have a small storage server with several SATA drives running ZFS on 9.2-RELEASE. Due to various issues (mostly dealing with noise and power consumption), the system was spec'ed with a power supply that requires spinning up the disks one by one. This problem is easily solved for boot-up by enabling power-up in standby on the drives and setting CAM_MAX_HIGHPOWER=1, which seems to work fine. I'm also interested in allowing the drives in the ZFS pool to spin down after a period of inactivity. However, it sounds like CAM_MAX_HIGHPOWER doesn't help for this scenario (or maybe I'm wrong?) --- as far as I can tell, multiple drives would be allowed to spin up from standby at the same time. Is there an equivalent mechanism for staggering wake-up from standby on SATA disks? Thanks, Nuno Subtil
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