Sorry if this has been done to death recently but...

What sorts of disk systems are people using as disk staging to keep
LTO3s happy?  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.  We have pretty
much a 24*7 backup window with lots of slow & small, slow & big, and
some fast, clients.

It seems the idea that you need disk staging to keep your LTO tapes
running nicely, rings a bit hollow.  Also seems to me we're looking at
needing a high-end disk system.  Which makes a mockery of backing up to
cheap ATA/SATA disk being the way forward.

The only way I can see to get around the performance problems with
writing/reading backup streams to/from disk concurrently, other than a
high-end system, is to script some kind of mirror-split-off process and
use it to do the duplication with scripts rather than DSSU.  i.e. back
up to disk overnight & then split a mirror off (to somewhere where its
I/O will be separate) and duplicate off this during the day before
resynching.  Anybody do anything like that?  I can see all sorts of
nasty gotchas ... maybe that way madness lies?

cheers, Phil

Phil Weber
Business Technology (Egg)
Storage Technical Services - Senior UNIX Technologist
Phone: 01384 26 4136
Mobile: 07748 333503
Jabber: weberp at jabber.pn.egg.com

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