SUMMARY: Reduced scsi sync-speed

Sorry for late summary...

Problem was: reduced sync speed and no tagged queueing on one external 
u320 channel on a v240 running solaris 10 (kernel Generic_127111-06).

First try was a controller reset on the infortrend raid array. Rule number 
one: don't do this on mounted filesystems ;-) Although there was no i/o 
there where many scsi erros, and the ufs logs on the array went to state 
error. unmount and fsck was required, luckily no data loss after fsck. 
Controller reboot time was somewhat less than 1 minute, this seems larger 
than scsi and mpt driver timeouts.

Last weekend we rebooted the box and everything was ok again, both 
external scsi channels run in u320 mode.

Thanks to:

Nick Hindley: suggested scsi channel and cable problems
Chris Hoogendyk: reboot is necessary, renegotiation only on reboots
Matt M. Morris: same problem with some sdlt drives, sun suggested mpt
   driver patch, reboot as workaround
Anthony D'Atri: hit the nail on the head
   If there isn't redundancy, you will absolutely want to unmount the
   filesystems first.  Infortrend arrays take a long time to reboot.

Cheers,
Michael

Original question:

On Wed, 16 Jun 2010, Michael Hase wrote:

> Dear managers,
>
> on our v240 (solaris 10) with an external scsi raid array (hw infortrend
> raid controller) one of the two u320 scsi channels runs very slow. prtconf
> -v shows
>
>             Driver properties:
>                 name='target3-TQ' type=int items=1 dev=none
>                     value=00000000
>                 name='target3-wide' type=int items=1 dev=none
>                     value=00000000
>                 name='target3-sync-speed' type=int items=1 dev=none
>                     value=00001388
>
> the other channel looks ok:
>
>             Driver properties:
>                 name='target0-TQ' type=int items=1 dev=none
>                     value=00000001
>                 name='target0-wide' type=int items=1 dev=none
>                     value=00000001
>                 name='target0-sync-speed' type=int items=1 dev=none
>                     value=00027100
>
> The infortrend console also shows one channel running at 40mhz narrow
> instead of 160mhz wide, that's consistent with the prtconf numbers. We can
> verify the slow bus speed with a small i/o test with dd: 33 mb/sec on the
> slow channel vs. 120 mb/sec on the normal one.
>
> I hope that the scsi bus renegotiates to normal speed when resetting the
> array. The question is: can I safely reset the external raid controller on
> the array without rebooting the v240 having all ufs filesystems mounted?
> Better first unmount filesystems? Or is a reboot the only solution?
>
> Thanks in advance,
> Michael
>
> --
> i.A. Michael Hase
> michael@six.de
> http://www.six.de
> phone +49 711 99091 62, fax +49 711 99091-99
> Six Offene Systeme GmbH
> Am Wallgraben 99
> D-70565 Stuttgart
> Amtsgericht Stuttgart HRB 25128
> Geschaeftsf|hrer: Ralph Kissner, Robert Zwettler
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