Networker

Re: [Networker] SDLT full prematurely

2002-08-26 03:48:13
Subject: Re: [Networker] SDLT full prematurely
From: Preston de Guise <pdeguise AT BIGPOND.NET DOT AU>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Mon, 26 Aug 2002 17:40:00 +1000
On Mon, 2002-08-26 at 17:33, Lee Hwan Meng wrote:
> We use SAN switch to perform DDS. We also have mix of NTs and Unixs.
>
> Our error messages are quite similar to yours, except that we don't have
> SCSI lun resetting messages anywhere. This may make our debugging much more
> difficult (sigh...)
>
> I encountered 4 such errors for the past 10 days (I lost more than 200GB
> space on each tape since each time the error comes after just backing up
> less than 20GB of data). Everytime, it goes like this:

A worthwhile thing to check for is whether any other host on the SAN
that happened to be zoned into the tapes rebooted during the tape access
- or did something else "low level" on the SCSI bus.

Even with zoning in place, multiple hosts are usually configured to be
able to see the one tape drive, with NetWorker responsible for
coordinating the access to each drive.

When a host reboots or does something "nasty" at a low SCSI level,
depending on what HBA and host it is, it can send a SCSI reset to every
device on its bus(ses).

I know that you need to have your switches and HBAs enabled for FCP-2. I
believe (from memory, which is rather vague today due to a damn flu)
that you have to also disable RSCN.

Unfortunately HBA and Switch support for these options are often still
flaky or undocumented.

BTW, if you've got Win2000 in the SAN tape environment it's also worth
checking to see whether any of the Win2000 hosts have suddenly
re-enabled RSM. There appears to be some quirky conditions that will
cause RSM to "re-enable" on a W2K host, though I've never been able to
isolate it.

Cheers,

-Preston de Guise.

--
Preston de Guise <pdeguise AT bigpond.net DOT au>

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