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Date:      Fri, 26 Feb 1999 16:04:27 +0100
From:      User Girgen <girgen@partitur.se>
To:        Warner Losh <imp@harmony.village.org>
Cc:        freebsd-stable@FreeBSD.ORG, freebsd-current@FreeBSD.ORG
Subject:   Re: panic: aha0 Invalid CCB or SG list
Message-ID:  <36D6B7FB.C919EE6A@partitur.se>
References:  <36D4B092.8B076D55@partitur.se> <199902252308.QAA04402@harmony.village.org>

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Warner Losh wrote:
> 
> In message <36D4B092.8B076D55@partitur.se> Palle Girgensohn writes:
> : I've seen three crashes in the last couple of weeks, with a server
> : box that's been running stable as a rock for two years, at least. It
> : has an adaptec 2940UW with six disks, and an adaptec 1542CP that's
> : connected to a seagate travan tape driver.
> 
> OK.  This card is known to be good.  At least I've not had any
> problems with it.

Same here, until now.
 
> : It's running STABLE-3.1 from Feb 19 1999, and since the last
> : upgrade, I've seen three crashes, all related to dumping to
> : tape. Since I got no info on what happened, I decided to sit down
> : with the machine, run a backup sequence to tape, and wait for it to
> : possibly crash. After 90 minutes, I was about to give up when
> : suddenly, poof:
> :       panic: aha0  Invalid CCB or SG list.
> :
> : So, it's probably the 1540 driver (or hardware)?
> 
> Ah.  OK.  I'm not doing tape stuff on my machine.  How fast is that
> seagate tr-4 that you are doing?

It claims 600 Kbytes/s; normally around 550 Kb when at its best, but it
depends.
 
> : Can anybody shed some light on what to do? Is it software? That's my
> : guess, since the machine never ONCE has crashed until the upgrade to
> : 3.x. I had one crash when running current form beginning of January
> : (soon after moving to 3.x), and now theese three in a week. The 1540
> : has been in the machine for about six months.
> 
> Chances are really good that this is software.  The invalid ccb or sg
> list is due to either a race condition or something taht corrupts
> these things.
>
> : If there's anything I can do to help debug I'll do it, but device
> : drivers are a little above my level of expertise.
> 
> If you can wait a day or three, I might be able to find something that
> will help.  However, I don't have a tape drive right now to test it
> with.  I'll see what I can beg, borrow or steal.

I can wait, no problem.

It seems that the crashes occur when the CPU is 100% loaded. (The backup
system (amanda) is running gzip on dumps before writing to tape. It's a
parallell process: the client dumps and gzips, and sent the zipped file
over network to tape host, which puts it on a scratch disk. These files
are written to tape by the tape host. The crashes occur when the tape
host is scheduled for level 0 dumps itself, meaning it will perform gzip
at the same it is writing to tape. This explains why it doesn't happen
every night.)

Thanks a lot for helping!

/Palle


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