On 9/22/2006 4:19 AM, Weber, Philip wrote:
> What sorts of disk systems are people using as disk staging to keep
> LTO3s happy?  

We're using HP EVA with FATA (Fibre ATA) drives.  We don't drive the 
LTO3s at full speed, but I do not believe it's an EVA issue.

> Our current EMC Clariion Cx300 struggles to supply data fast enough
> to 3 LTO2 drives (even outside of NetBackup) and performance goes
> through the floor if (as is often the case) it is still trying to 
> write backups to disk while streaming data off to tape.

What sorts of benchmarks have you done to prove that it's a disk issue? 
  Have you done something like a dd to see how fast you can read data 
from the disk?  Have you monitored your switch ports?  I've witnessed 
our NetBackup environment hit 150MB/sec on our master server's 2Gbps 
switch port doing a dd from the DSSU to /dev/null.  My destaging 
performance to LTO-3 is normally quite poor so I know I've got a 
NetBackup issue somewhere.

> We have pretty much a 24*7 backup window with lots of slow & small,
> slow & big, and some fast, clients.

I think that describes most of us...  Do your fast clients drive the LTO 
directly at a good speed?

        .../Ed

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