Adaptec 2410SA starts doing this: aac0: COMMAND0xc551a7e8TIMEOUTAFTER 147 SECONDS (Modified by Chad Leigh -- Shire.NetLLC)

Scott Long scottl at
Thu Mar 18 23:26:54 PST 2004

In between 5.0 and 5.1 I put some serious work into the driver to make
it perform better.  Unfortunately, I opened up an edge case that would
result in a command being lost under extreme load.  It was very hard to
reproduce locally until I did some more performance work after 5.2.  I
finally made the driver so fast that I could reproduce the problem with
ease, which then allowed me to figure it out.  A band-aid went into
5.2.1, and the real fix (hopefully) is in 5.2-CURRENT.


Aaron Wohl wrote:
> We got command timeout with the aac driver off and on for about a year
> with a 5400s and various freebsd versions.  Ive been sending Scott the
> info and he has tried various fixes.  I switched one of the machines to
> 5.2.1 a couiple of weeks ago.  It been ok so far.  Buts sometimes it may
> go a month or two then happen a lot so hard to say for sure yet.
> When it has happened to us power cycling and rebooting gets it unwedged
> -- reset does not.
> On Wed, 17 Mar 2004 10:31:48 +0100, "Albert Shih" <shih at>
> said:
>> Le 05/03/2004 à 22:05:25-0700, Scott Long a écrit
>>>On Sun, 29 Feb 2004, Chad Leigh -- Shire.Net LLC wrote:
>>>>Now the machine, when it tries to check the two aacd volumes on this
>>>>controller, starts printing out this message below every 20 seconds or
>>>>so and the disk volumes cannot be used.  Each new IO attempt triggers a
>>>>new set of these messages.  The hex number after the COMMAND word is
>>>>different for each new IO request but of course stays the same for
>>>>repeated messages relating to the same original IO request
>>>>aac0: COMMAND 0xc551a7e8 TIMEOUT AFTER 147 SECONDS
>>>>I have googled on this and similar posts related to 2120S controllers
>>>>all seemed to have different causes and fixes...
>>>I thought that 5.2.1 would have fixed all of this.  This isn't good.
>>>>Any hints or ideas on what is causing this?  I can get into the
>>>>controller at POST time and it checks out...
>>>Can you boot the machine at all?  If so, could I feed you some patches to
>>>help diagnose the problem?
>>Long time ago (humm 3 mounths ;-)) ) I've same problem with a Adaptec
>>on FreeBSD 5.2
>>The reconstruction don't work and sometime the machin hang up with same
>>kind of message.
>>I solve the problem (after many time) by to remove the SCSI terminator on
>>the array (where I put the hot-plug disk).
>>Hope this help.
>>Albert SHIH
>>Universite de Paris 7 (Denis DIDEROT)
>>U.F.R. de Mathematiques.
>>Heure local/Local time:
>>Wed Mar 17 10:29:24 CET 2004
>>freebsd-scsi at mailing list
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