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NDMP Backup with Netbackup 7.1 of EMC-Celerra Problem with type=vbb

Rolf_Heitfeld
Level 2
Partner Accredited

Hi all,

the data of our costumer grows on and on. In fact we got filesystems with > 50.000.000 Files - all small jpg files with an average file size of 9kB. Normally we back up the filesystems with the type=tar option, but these filesystems took now almost two days to back up with a performance of aproximately 4 MB/sec. This is not amazing, as the you can restore single files and as a consequence each file has to be attached. So we tried the option TYPE=VBB as described here:

http://www.symantec.com/business/support/index?page=content&id=TECH31885
  NDMP volume backup (VBB)
The NetBackup policy’s Backup Selections list can specify that the backup is
performed using EMC’s NDMP Volume Backup.
Example of NDMP volume backup entries in the Backup Selections list:
set snapsure=yes
set type=vbb

I thought, that this has to be much faster als the whole volume is backed up block wise. - But the opposite happens - It took even longer!
Has anybody an idea why?

with greetings from Germany

rolf

2 REPLIES 2

VirtualED
Level 5
Employee Accredited Certified

That is quite the situation.  NDMP is not tolerant of many small files, and the more files you add the more inodes are used causing NDMP to slow down more and more.  I assumed you already tried to perform a dump to null to see the best speed possible.

You may need to revisit the implementation.  Basically don't so many files on one filesystem.  However in the interim, you can try running the policy without history.

A decent blog was written on this topic:

http://unixadministrator.blogspot.com/2010/05/fast-ndmp-backups-revealed.html

Solution: The solution was to use "set HIST=n" option in each of the NDMP backup pollicies so that NDMP job do not need to update catalog what it is backing up. Result: Faster backups!!! While I got backups faster with this method, this has its own advantages and disadvantages. Here is the list:

Advantage:
1) Backup performance is significantly improved
2) Catalog size is now controller (because it has to capture less info)
3) Catalog backup size is significantly reduced
4) All backup jobs are giving at least 30-40 MBPS while faster jobs are still same

Disadvantage:
1) No file history is captured!!!
2) Meaning that if I have to restore a file, I will have to restore entire filesystem to do so
3) The size of restore volume must be greater or at least equal to largest volume which is getting backed up
4) Also, the number of inodes also must be equal or more in order to restore largest size volume in environment.
 

teiva-boy
Level 6

There are two other options to solve this.

 

1.  Synthetic backups of the file shares.  From a host with the shares mounted you back these up, and with synthetic's you're only backing up the files that have changed and create synthetic "fulls," over time.  This is something that NBU can do well if you set it up right.

2.  Change products and for it's NDMP funtion, Avamar.  Avamar does a level 0 initially, and a level 1 NDMP forever, merging level1 into the level0 as it needs to whenever you need to restore a file.

 

I think #1 is not a bad idea to try out...  Just imagine in 3yrs you moved to a new NAS platform, NDMP is propietary and you wont be able to restore your NDMP from EMC to an NDMP device from XX brand.  At least with #1, you can restore to ANYWHERE there is an NBU client.