Date: Sat, 21 Jul 2007 00:15:34 +0100 From: Tom Judge <tom@tomjudge.com> To: Michael Worobcuk <mail@michaelworobcuk.de> Cc: freebsd-stable@freebsd.org Subject: Re: Dell PERC5/i SAS5/5IR - RAID monitoring Message-ID: <46A14216.5010507@tomjudge.com> In-Reply-To: <4837D0B1-93C2-4476-8D91-7D2586722458@michaelworobcuk.de> References: <4CC93356-890C-43DF-A905-0B9ABC990223@michaelworobcuk.de> <469D5061.8060306@tomjudge.com> <2F1F8117-86EF-49B4-AB4E-8A656727570A@michaelworobcuk.de> <469DE961.9060608@tomjudge.com> <932C632C-A89B-427F-92EC-71B351D66D17@michaelworobcuk.de> <46A134AB.2050803@tomjudge.com> <4837D0B1-93C2-4476-8D91-7D2586722458@michaelworobcuk.de>
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Michael Worobcuk wrote: > > Am 21.07.2007 um 00:18 schrieb Tom Judge: > >> Michael Worobcuk wrote: >>>> Tom Judge wrote: >>>> >>>> As for performance issues with the SAS5/i, there is a problem in the >>>> controller. A work arround was created by Scott Long which created >>>> a sysctl that could be set to cause the controller to turn on the on >>>> drive write cache's. These changes where commited to RELENG_6 on >>>> 2007-06-05 21:32:57 UTC. >>>> >>>> >>>> ... >>>> >>>>> >>>>> Here is the original commit log: >>>>> >>>>> scottl 2007-06-03 23:13:05 UTC >>>>> >>>>> FreeBSD src repository >>>>> >>>>> Modified files: >>>>> sys/dev/mpt mpt.c mpt.h mpt_cam.c >>>>> Log: >>>>> mpt.c: >>>>> mpt.h: >>>>> Add support for reading extended configuration pages. >>>>> mpt_cam.c: >>>>> Do a top level topology scan on the SAS controller. If >>>>> any SATA device are discovered in this scan, send a passthrough FIS >>>>> to set the write cache. This is controllable through the following >>>>> tunable at boot: >>>>> >>>>> hw.mpt.enable_sata_wc: >>>>> -1 = Do not configure, use the controller default >>>>> 0 = Disable the write cache >>>>> 1 = Enable the write cache >>>>> >>>>> The default is -1. This tunable is just a hack and may be >>>>> deprecated in the future. >>>> >>> I set mpt.enable_sata_wc to 1, as hw.mpt.enable_sata_wc is, AFAIK not >>> tunable in mpt_cam.c. This did not take any effect to the >>> performance. Is there anything else to change ? >> >> Not that I know of, do you have SAS or SATA disks attached to the >> controller? > > yes, SAS. > > In that case the above sysctl is not going to work for you as as the name suggests it is only for sata devices. For someone with a bit more SCSI experience than me: Could this be solved by setting the WCE (Write cache enable) bit in the modepage (8) on sas devices if it is not already set? The driver could make this change on SAS devices during the topology scan in similar way to the way it does for SATA devices? Tom
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