On Tue, Jul 11, 2006 at 05:51:50PM -0400, Justin Piszcz wrote:
> The group I work with is expecting 160-200MB/s megabytes per second on an 
> LTO3 with compression.  I did some tests today with 7 RAID1 SCSI drives.
> 
> 67GB x 7
> 
> On each volume was 3 20GB tar files.
> I got 78-82MB/s sustained total, 12-16MB/s on each thread (7 
> multistreamed).
> 
> The tar files are representative of a typical file system in our 
> environments.

For starters, Veritas has instructions on how to test for the speed by
backing up to the null device.  Start with that so that you know how
fast your disk subsystem is.  There are also some network speed tests
out there (the name of the one I've used escapes me at the moment).
Then at least you've got the inputs into the tape drive narrowed down.  

I would be shocked to see you anybody get 160-200MB/second compressed -
I've heard 60-80 is about the limit and you're there.
 
> What speeds have other members gotten when doing speed testing to LTO3 
> drives?

We've done no tuning yet (the drives just went in) and we're topping out
at around 55-60.

        .../Ed

-- 
Ed Wilts, Mounds View, MN, USA
mailto:ewilts at ewilts.org