Date: Thu, 28 Jan 2010 18:26:09 +0100 From: Tijl Coosemans <tijl@coosemans.org> To: freebsd-hackers@freebsd.org, Alexander Best <alexbestms@wwu.de> Subject: Re: Spin down HDD after disk sync or before power off Message-ID: <201001281826.10472.tijl@coosemans.org> In-Reply-To: <permail-20100126191723f7e55a9d00001a52-a_best01@message-id.uni-muenster.de> References: <permail-20100126191723f7e55a9d00001a52-a_best01@message-id.uni-muenster.de>
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On Tuesday 26 January 2010 20:17:23 Alexander Best wrote: > because of kern/140752 i looked through a discussion back in 2009 > (http://lists.freebsd.org/pipermail/freebsd-hackers/2009-March/027879.html) > concerning freebsd's hdd spin down procedure. right now > ATA_FLUSHCACHE is being used although the hitachi hdd specs > referenced in the pr say that this will not cause proper load/unload > and thus an emergency unload will occur which reduces the life > expectancy of hdds dramatically (20.000 shutdowns vs. 600.000 > shutdowns). unfortunately the discussion back then didn't come up > with any sort of decision/patch. > > attached you'll find a very simple patch which issues > ATA_STANDBY_IMMEDIATE instead of ATA_FLUSHCACHE during hdd spin down. > > could somebody with hdd knowledge comment on this? this matter seems > quite important since there may be a chance that the current spin > down mechanism in freebsd damages hdds! > Index: sys/dev/ata/ata-disk.c > =================================================================== > --- sys/dev/ata/ata-disk.c (revision 202848) > +++ sys/dev/ata/ata-disk.c (working copy) > @@ -191,8 +191,9 @@ > { > struct ata_device *atadev = device_get_softc(dev); > > - if (atadev->param.support.command2 & ATA_SUPPORT_FLUSHCACHE) > - ata_controlcmd(dev, ATA_FLUSHCACHE, 0, 0, 0); > + if (atadev->param.support.command2 & ATA_SUPPORT_STANDBY) This is the wrong bit. ATA_SUPPORT_STANDBY indicates whether a drive can be powered up straight into standby mode. The ATA_STANDBY_IMMEDIATE command is part of the standard power management feature set, so this line should be: if (atadev->param.support.command1 & ATA_SUPPORT_POWERMGT) > + ata_controlcmd(dev, ATA_STANDBY_IMMEDIATE, 0, 0, 0); > + > return 0; > }
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