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I have a couple of customers using DSSU's in NBU6.  First of all, I do use 
storage unit groups
with multiple DSSUs as part of them.  Almost all have "re-used" existing 
storage as a general
trend, so the back end storage has been RAID 1 or RAID 5 more times than not.  
The size of each
DSSU depends on what the client profiles, back end storage density and 
policy/schedule quantities
and frequencies.  Kind of need to put all that in your brain and make a best 
guess.  I have found that
setting the mfs on the DSSU hasn't aided any of the situations I've set up and 
in fact
when using multiple DSSUs in a storage unit group, the smaller (512mb) mfs has 
better distribution
on smaller sides DSSUs.  Flushing is done only after phase 2 is complete and 
successful.  So if
your schedule is not frequent enough, it will not prune out images as there 
would still be only
1 copy of that backup image.  Looking forward to next updates when the volume 
pool can be specified
at a more granule level instead of all disk staging for that DSSU goes to one 
pool.  I've taken
the approach for some customers to have cumulative or incrementals go to DSSUs 
and fulls and archives
go strait to tape.  Also, setting the storage unit group usage profile is 
something to consider if
you go that route (prioritized, least used and failover).  As far as HWM and 
LWM, I've generally
left the HWM default (98%) and set the LWM to sometimes 60%, but that depends 
on the available resources
for phase 2 and the frequency as well.  If you want to have the most possible 
images on disk for
faster restores, then taking your LWM down to 40% will make that difficult.

Thanks
Peter

Peter DrakeUnderkoffler
Xinupro, LLC
617-834-2352



Martin, Jonathan (Contractor) wrote:
> I'm working on architecting a new backup solution here, which will 
> undoubtedly require Disk Staging to accommodate faster drives (LTO3 or 
> DLT-S4.)  I'm sure this is a common way to get around the limited bandwidth 
> associated with copper network connections.  Anyhow, how big is everyone's 
> DSSUs?  2x Media?  More?  How about your High Water Marks?  I'm thinking 
> something along the lines of 50% high water mark with DSSU's 2x Media 
> (compressed.)  Also, lets say your DSSU gets up to 40% when the backup window 
> finishes, is there a setting to flush this after a certain amount of time?  
> I'm installing 6.0 for the first time here shortly, so all the new features 
> are presently a mystery to me.
> 
> TIA,
> 
> -Jonathan
> 
> 
> _______________________________________________
> Veritas-bu maillist  -  Veritas-bu at mailman.eng.auburn.edu
> http://mailman.eng.auburn.edu/mailman/listinfo/veritas-bu
> 
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