On 12/21/06, Steve Kirkpatrick <skirkpatrick at ghx.com> wrote:
> NB5.0MP6
> Master server: Sun V440 w/ 4x1.2GHZ SPARC III, 8GB RAM running Solaris 10
> Sun L500 library with four HPUltrium LTO-3 drives connected to master server
> via 2GB SAN.
>
> I can't seem to get more than 12.5MB/sec throughput on these LTO-3 drives.  
> That
> is about the same as I am getting on another server's SCSI-connected LTO-1 
> drives.
> I see the same performance whether I am duplicating tapes using bpduplicate or
> when I am backing up clients over a gigabit network.
>
> After reading all of the recent threads concerning tape drive performance,
> shoeshining, etc, I can't believe that the master server is only able to feed
> 12.5MB/sec of data to these drives.

You bottleneck is most likely the network and/or the source system.  A
gigabit network maxes out at 35 MB/sec in some cases. Getting better
than 50 MB/sec is rare.

> Some of the previous threads on the subject suggested multiplexing jobs across
> drives but I worry that doing so will cause my duplicate jobs to take longer 
> as well
> as hamper restore performance.  Need I be worried about that?

If you don't multiplex, then your max speed for the tape will be the
max speed of the server yo are backing up.  If you factor in the
compression ratio, you will have an even more difficult time
maintaining the minimum sptreaming speed.

You almost certainly need to use multiplexing and cut down the number
of active drives in your storage unit.   Try 1 drive and MPX=4.   If
you can add a network link you should be able to add a second drive to
your storage unit.

Austin