Date: Fri, 9 Jun 2006 12:08:15 -0700 (PDT) From: Doug White <dwhite@gumbysoft.com> To: Chris Hedley <cbh-freebsd-current@groups.chrishedley.com> Cc: current@freebsd.org Subject: Re: aac0: COMMAND 0xffffffffxxxxxxxx TIMEOUT AFTER xx SECONDS Message-ID: <20060609120159.I60598@carver.gumbysoft.com> In-Reply-To: <20060609163735.D829@aga.cbhnet> References: <20060609163735.D829@aga.cbhnet>
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On Fri, 9 Jun 2006, Chris Hedley wrote: > I've been receiving this message quite a lot lately if I put my Adaptec > 2410SA aac controller under really heavy load. A quick look at the archives > suggests that it used to be a problem a couple of years ago, but was > apparently fixed. Personally I've had no bother with it until a few months > ago when I upgraded my version of -CURRENT, at which point it started > misbehaving. I assume you've checked cabling and termination? Frequently, driver updates can improve performance which means less tolerance for marginal configurations. > I'm also wondering if I might not be better off actually replacing the card > with something better, or at least something better suited to FreeBSD: with > the discs' and controller's write-caching turned off, the 2410SA is s-l-o-w, > about 6MB/s for contiguous writes to an array (either RAID-5 or RAID-10) > (benchmarked using the admittedly somewhat crude "dd various block sizes > to/from a /dev entry" technique), although reads are acceptable at > ~50-60MB/s, if not especially earth-shattering. Any suggestions (for > something inexpensive! If money were no object I'd've gone for a SCSI-only > system), or might I just as well stick with the 2410SA? 6MB/s sounds like you aren't getting any help from the card's write cache; its having to do stripe reads to recalculate parity instead of doing full stripe writes. Many cards disable write-back cache if the battery module isn't present -- make sure you have one and its working. /dev accesses also use physio so you don't get any benefit from write combining in the filesystem layer. Also, in general, hardware RAID beats PCI RAID, hands down. -- Doug White | FreeBSD: The Power to Serve dwhite@gumbysoft.com | www.FreeBSD.org
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