On Mon, 18 Sep 2006 11:58:38 -0500 (CDT)
Joe Royer <jroyer at digitalmotorworks.com> wrote:

> Forgive me if this has been asked before, I'm a bit behind on reading 
> the list.
> 
> How do you keep your LTO3 drives spinning fast enough?
> 
> I have a meeting with an idiot manager who refuses to believe that we
> can't stream fast enough to use LTO3 without damaging the tape and/or
> drive.  I have limited DSSU space.  I have been in environments in the 
> past where shoeshining was normal and so was the 20% failure rate and I 
> don't want to go back.  It is my understanding that most people aren't 
> spinning LTO3 fast enough and are living with higher failure rates.

Keep in mind that LTO3 drives are able to stream at several different rates, so 
even if you can't get the full bandwidth that the drive can write at, as long 
as it's greater than 20MB/sec, you're not harming the drive.

> The only thing I can think of is to send everything to DSSU first (TSM 
> anyone?), but NBU sucks at telling you the throughput there so I'm not 
> sure I trust that anyway.  Any tricks for getting throughput numbers out 
> of NetBackup (5.1) DSSU duplicates are very welcome.

If you look at the "All Log Entries" report, you should be able to see the 
bandwidth of your duplicates. These entries come from 
/usr/openv/netbackup/logs/bptm/log.<date> or 
/usr/openv/netbackup/db/error/daily_messages.log.
 
> My backup master with a 6-drive internal RAID-10 can barely hit 27MB/s 
> reliably doing OS backups, but my DSSU is on SATA SAN drives and hard 
> to measure.

We've been very happy with the 3-ware controllers and SATA disks. Getting more 
than 80MB/sec out of them at times.

--andy.

--------------
Andrew Sydelko
Engineering Computer Network
Purdue University