Re: Mixing disk and tape devices in a SAN environment (166 Views)
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Frequent Advisor
Chetan_5
Posts: 71
Registered: ‎03-26-2003
Message 1 of 6 (166 Views)

Mixing disk and tape devices in a SAN environment

All,

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 ...
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Honored Contributor
Court Campbell
Posts: 1,605
Registered: ‎08-12-2004
Message 2 of 6 (166 Views)

Re: Mixing disk and tape devices in a SAN environment

I don't see how it is any different than having multiple disk arrays on the same san. I personally have worked in two shops that used the same same switch for tape and storage arrays without issue.
"The difference between me and you? I will read the man page." and "Respect the hat." and "You could just do a search on ITRC, you don't need to start a thread on a topic that's been answered 100 times already." Oh, and "What. no points???"
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Exalted Contributor
Steven E. Protter
Posts: 33,806
Registered: ‎08-15-2002
Message 3 of 6 (166 Views)

Re: Mixing disk and tape devices in a SAN environment

Shalom,

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.

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Honored Contributor
Alzhy
Posts: 4,373
Registered: ‎01-22-2002
Message 4 of 6 (166 Views)

Re: Mixing disk and tape devices in a SAN environment

Chetan,

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
Hakuna Matata.
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Honored Contributor
Dave Hutton
Posts: 579
Registered: ‎11-14-2003
Message 5 of 6 (166 Views)

Re: Mixing disk and tape devices in a SAN environment

It was suggested to me 3 years ago to put our tapes on a different HBA then the disks.
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.

For example:
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.

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Acclaimed Contributor
Torsten.
Posts: 23,251
Registered: ‎10-02-2001
Message 6 of 6 (166 Views)

Re: Mixing disk and tape devices in a SAN environment

I think you should create separate zones for tapes and disks at least.

Hope this helps!
Regards
Torsten.

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