Networker

Re: [Networker] SAN Backup Block size Woes..

2003-08-27 12:32:07
Subject: Re: [Networker] SAN Backup Block size Woes..
From: Paul Esson <paul.esson AT REDSTOR DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Wed, 27 Aug 2003 17:20:12 +0100
Having spent some time looking at SAN environments I can understand Davina's 
line of thought here.  I recently experienced a similar situation to the one 
confronting Kent.  In this case the host type was UNIX but the symptoms were 
similar.

Basically, we had some SCSI cable/terminator issues that were generating lots 
of parity errors on the SCSI side of the routers (converters).  This would 
result in the following scenario:

- NetWorker is reading away 96K blocks (DLT8000)
- Parity errors occur
- NetWorker is still attempting to read the tape
- Router resets the SCSI bus
- Reset of SCSI bus will cause a re-initialization of the tape drives
- Tape drives will rewind when initialised
- NetWorker successfully reads a block from the tape, expecting it to be a 96K 
data block
- NetWorker gets the 32K tape header block on the tape
- Error message about the block size mismatch is generated

Regards,

Paul Esson
Senior Support Engineer
Redstor Limited

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-----Original Message-----
From: Davina Treiber [mailto:treiber AT HOTPOP DOT COM]
Sent: 27 August 2003 17:05
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Subject: Re: [Networker] SAN Backup Block size Woes..


>        This causes a 'Block size is 32768 bytes not 131072 bytes. Verify
the device configuration. Tape position by record is disabled.'

If this was a pure block size configuration issue, wouldn't this be saying
65535 bytes, not 32768? Whatever other problems you have in this
environment, this machine is reading back something from the tape that it
doesn't think it put there. This indicates some kind of corruption.

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