Re: SCSI bus resets w/Linux 2.4.x and Mylex DAC960 RAID
Date: Mon, 4 Jul 2005 18:59:47 GMT
In <firstname.lastname@example.org> email@example.com writes:
>A client has a 3-disk SCSI RAID array attached to an old Mylex DAC960
>controller. About six months ago, they lost one of the disks, which was
>fine, except there was no alarm and they didn't notice... Last
>Wednesday at 9:03AM, they lost a second disk - and believe me, *that*
>got their attention. :}
>They replaced the two failed drives (older 10K IBM models) with newer
>Seagates in the same drive caddies, leaving the remaining working IBM
>drive in place (don't ask...). All drives are 18GB SCSI. After the
>array was rebuild and yours truly resurrected things from backup tapes,
>we noticed that the system was slow and there were huge "gaps" in
>activity where for 5-8 seconds seemingly nothing was getting processed
>and no disk activity was happening. Long story short we found that the
>SCSI bus was undergoing a full reset every minute or so (see dump
That's not a dump of a SCSI bus reset. This would reveal what drive caused
the reset (reset on behalf of....).
>So here's the question: assuming termination and cables are all fine
>(as the old drive caddies were reused in their same positions, and they
>look OK), could the fact that we've got two different types of drives
>in the same array be causing the resets? I've heard tale tell the
>DAC960 is pretty finicky about the types of drives it likes to talk
>to. And I've never tried to do hardware RAID with dissimilar drives (of
>different generations, no less) before.
Well, all hardware RAID controlers are picky about drive FW and drives
of different types. It would be interesting to see what really collided
in the log.
> Logical Drives:
> /dev/rd/c0d0: RAID-5, Online, 35844096 blocks, Write Thru
> /dev/rd/c0d1: RAID-5, Online, 35840000 blocks, Write Thru
2 RAID 5's? On 3 drives? Are you sure that's right?
-- Dipl. Inf. Ulrich Teichert|e-mail: Ulrich.Teichert@gmx.de Stormweg 24 |listening to: Suicide Drive (The Deep Eynde) 24539 Neumuenster, Germany|Public Pervert (Interpol) Cauchemar (Opération S)