topic Re: Disk and tape on the same SAN in Disk

Disk and tape on the same SAN

Leif Halvarsson_2 — Mon, 31 Mar 2003 20:07:21 GMT

Hi,
There has been some questions about having disks and tape drives on the same SAN. Here is an interesting link.

http://searchstorage.techtarget.com/tip/1,289483,sid5_gci864720,00.html

Re: Disk and tape on the same SAN

Michael Tully — Tue, 01 Apr 2003 00:33:04 GMT

Hi Leif,

The only argument I would add to this is about having disks/tape/host in the same zone set for your switch.
I would have the two types segregated:

host/tape
host/disk

Cheers
Michael

Re: Disk and tape on the same SAN

Grahame Macmillan — Tue, 01 Apr 2003 12:53:39 GMT

Hi Leif,

Michael is correct. You can have disk and tape in the same SAN as long as they are zoned to different HBA's. What vendors wont support is putting disk and tape io down the same fiber card. You have to have a seperate fiber card in a server for each.

Grahame

Re: Disk and tape on the same SAN

Dave Wherry — Wed, 02 Apr 2003 15:36:31 GMT

There is a reason not to have tape and disk on the same SAN and I have been burned by it. You can work around it though.
If you add a new LUN to your fabric and assign it to a host, the host will probe the bus to find that new LUN. This can be done on-line. This creates an interupt on the bus that disks can handle. They will just retry their I/O.
Tapes are a streaming process and do not like the interupt. If a backup or restore is running when this interupt occurs the job will fail.
So, either keep the disks and the tapes on different SAN's (zones) or just be very carefull. If tape activity is happening, do not add new LUN's.