06-18-2007 06:45 AM
We all know perils of mixing tape devices and disks on the same SCSI bus. Does that same concept apply to SAN environments?
I am working in a comparatively smaller shop and in the past have worked in larger environments where there was a dedicated tape san.
I am looking for feedback from a management and performance point of view ...
06-18-2007 07:00 AM
06-18-2007 07:01 AM
To some degree the same problems exist.
If a tape drive is on the same hba as a busy set of disk LUNS performance will suffer.
Owner of ISN Corporation
06-18-2007 07:18 AM
Some years back it was considered best practice to NOT mix tape and disk LUNs on the same HBAs to your servers. Many many sites still do and my current client is no exception. In fact, it is still hugely popular to have separate SANs for Tape and Tape-like devices (aka a TAN pr Tape Area Network) and for disks (Storage arrays).
One very obvious reason would be performance - if you happen to be backing up data on disks that is presented on the same FC path as your Tapes - of course you'd have performance and throughput issues.
Of course, those who embraced Serverless Backups (i.e. Vertex initiative of Veritas/Symantec and Legato's Serverless backups) - you would not have to contend with Tape LUN presentations on your servers.
I would additionally advice checking the SAN Device Guides from HP or whatever SAN vendor you're using.
Nelson @ "bored" on Day Uno of HPTF 2007
06-18-2007 08:17 AM
I'm not sure if this is true anymore (or if it ever was), but I guess one of the reasons given to me. If a device (tape or disk) were to have a fiber channel storm on one device it could cause issues on the other devices.
If a tape drive started to have a large number of fiber errors and it was on the same HBA, it could affect the disk. So I basically was told separate zone and separate HBA to isolate anything like this from happening.
06-18-2007 10:35 AM
Hope this helps!
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