[Beowulf] Re: OT: LTO Ultrium (3) throughput?

[Steve Cousins]

> Just under 60MB/sec seems to be the maximum tape transport read/write
> limit.  Pretty reliably the first write from the beginning of tape was a
> bit slower than writes started further into the tape.

I believe LTO-3 is rated at 80 MB/sec without compression. Testing it on 
our HP unit in an Overland library I get:

WRITE:

dd if=/dev/zero of=/dev/nst0 bs=512k count=10k
10240+0 records in
10240+0 records out
5368709120 bytes (5.4 GB) copied, 71.8723 seconds, 74.7 MB/s

READ:

dd of=/dev/null if=/dev/nst0 bs=512k count=10k
10240+0 records in
10240+0 records out
5368709120 bytes (5.4 GB) copied, 69.2487 seconds, 77.5 MB/s

I used a 512K block size because that is what I use with our backups and 
it has given optimal performance since the DLT-7000 days.

Good luck,

Steve
______________________________________________________________________
  Steve Cousins, Ocean Modeling Group    Email: cousins at umit.maine.edu
  Marine Sciences, 452 Aubert Hall       http://rocky.umeoce.maine.edu
  Univ. of Maine, Orono, ME 04469        Phone: (207) 581-4302