There's also a lot more recovery issues when a link to a tape goes down,
than when a link to a drive/volume goes down.

I have all the servers and storage on my SAN multipathed, but keep my
tape drives single.


-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Len
Boyle
Sent: Wednesday, July 27, 2011 5:04 PM
To: David Magda; Veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] multipathing with tapes on Linux?

David, 

I think the answer depends on what you mean by multi-pathing, and the
maker of the tape drive.

The new IBM tape drives include two ports. But I think that it is only
for failover. And I suspect that the support would only be in the IBM
tape driver. Which  was released with it's source code the last I
looked.

I also suspect that you do not need multi-pathing to feed the tape
drives.  The  native speed for  a lto-5 tape drive is greater than that
of a gige card. And if you send data that can be compressed 2-1 or 3-1
then  even more so. 

The hard part is getting the data off the disk fast enough to drive the
tape drive.

len

-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of David
Magda
Sent: Wednesday, July 27, 2011 4:45 PM
To: Veritas-bu AT mailman.eng.auburn DOT edu
Subject: [Veritas-bu] multipathing with tapes on Linux?

Hey,

Anyone know if Linux (specifically RHEL 5.x) supports multi-pathing to
tapes? Is it worth setting up a media server with a 10 GigE interface
and two (or more) FC connections on the other?

AFAICT, the "device-mapper-multipath" only support MPIO for block
devices.
Is this assessment correct?

Thanks for any info.

Regards,
David


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