Hello,
I cannot confirm as i have not done any testing with backing up a volume 
vs qtree in the filer  volume, someone else can relate their experience.
On the backup time, it is my understanding that with ability to multiplex 
DSA backup & Jumbo Frame support technique yields comparable or better 
performance ( for GB ethernet) vs FC attached Tape drive ( i am only 
referring to one tape drive-one data stream scenario), while using 
multiple FC tape drives and splitting up Filer backups may yield better 
backup time with FC.
HTH



"Kuin, CNM" <CKuin AT WLZ DOT NL> 
Sent by: EMC NetWorker discussion <NETWORKER AT LISTSERV.TEMPLE DOT EDU>
02/26/2008 06:10 AM
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Subject
Re: [Networker] Long NDMP Backups






> You could backup the volumes on separate days, but since you 
> are already doing a DSA backup (backing up via the net rather 
> than direct backup), you are already getting the advantages 
> of parallelization and variable block lengths. To increase 
> the parallelization, you can change to backing up by qtree's 
> rather than volumes. Each qtree will be parallelized with the 
> backup. Also, the delay in the nsrdump is reduced since it 
> has to walk a smaller part of the volume.
> 
I was told NDMP isn't that efficient when defining qtree's vs volumes in
savesets.
It may limit the amount of data sent to the backupserver but it
increases the overhead on your filer because it has to determine, for
each saveset, which files to send over the wire. If you backup the
volume it has to do this once. If you backup per each individual qtree,
the filer has to do this X times.
Resulting in long wait times before data gets send over the wire.

I do think 12 hours to be quite fast btw. Our filer (3050, ONTAP 7.2.1)
does 2582GB, 8249432 files, in 16h 47m.

With regards,

Cor Kuin
Sysadmin
Waterlandziekenhuis

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