Actually I think the problem has only to do with block size.
I can backup clients of any size if they are Solaris to this tape library.
Its only when I start backing up Windows hosts that the problem appears.
We are also using zoning on the SAN switches.
I have 2 zones that contain the following

CrossRoads10K and Networker Server
CrossRoads10K and Windows DDS Storage Node

The Storage node sees the tapes and changer just fine as does the Solaris 
machine.
All of the Solaris hosts I have tested with show no problem writing large or 
small amounts of data to the tapes. 
The block size (On the Networker Solaris server) via scanner shows up as 128K.
If I label a tape on the Windows DDS Storage Node the tape shows up as 64K 
instead of 128K.

This is terribly frustrating because there is so little documentation for this 
and what I have found all points to Adaptec SCSI cards registry settings and 
thats it.

I have made the changes that the Legato Admin guides say you need to make when 
you have this setup (NSR_DEV_BLOCK_SIZE_SDLT=128) on both the Networker server 
and the Storage Node.

Thanks again for all the replies! 
No solution yet but still hoping.. :)

-----Original Message-----
From: Davina Treiber [mailto:Treiber AT hotpop DOT com]
Sent: Wednesday, August 27, 2003 2:29 AM
To: Legato NetWorker discussion; Kent Holloway
Subject: Re: [Networker] SAN Backup Block size Woes..


Kent,

I don't think your problem is block size settings at all. You have spent 
a lot of effort in diagnosing the problem based on the text of the error 
messages, but you have shown that 128KB block sizes are being written to 
the tape, so this is probably not the problem.

The clue is that the Windows storage node reports the error. Whatever 
the block size setting for this, it should consistently write the same 
block size. Also, the block size issue is not usually a problem with the 
Emulex fibre HBA on Windows, its driver has quite a high limit (512KB?) 
on block size.

What I think you are seeing is some kind of error in communication on 
your SAN. There are many possible causes of this, but it is likely that 
it is caused by other machines connected to the SAN, perhaps sending bus 
resets or other packets. These types of problems are difficult to track 
down, but you can help by setting up zoning on your SAN. I suspect part 
of your problem is that you are using the same HBA for disk and tape, it 
could be that communications to your disks are interfering with tape 
communications.

Sorry not to be able to be specific, but it should help you to know that 
it is probably not block size settings causing the problem. The message 
you are seeing means that it is reading back a block of an unexpected 
size, and that is probably caused by a SAN based error.

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