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8 Krypton

NDMP backup performance of a de-duped/compressed file system

Hi,   Has anyone any experience of slow backups with NDMP VBB backups of de-duped/compressed file systems on VNX using backup exec 2010 R3?    I am currently getting 2MB/s using VBB but when I switch to dump I get 65MB/s. I thought VBB would be quicker! The file system is 5TB. Regards Smarti. PS. Sorry about no new line. Can't get that to work in this browser anymore. Help with that would be appreciated as well

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

An update on this. Left the job running to completion and it seems that the start of the backup starts very slow and gets quicker as it goes. The full backup averaged about 50MB/s which doesn't seem that bad but has anyone got an explanation of why it revs up slowly? In the server log it seems to count the number of files by size at the very start which obviouly takes a long time on a large file system. Could this be the issue?

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

If you do a VBB backup with history I think that at the start it has go though the file system to generate a list which file is using which blocks (for single file restore).

Measuring backup rates you should always look at the complete backup time divided by the amount of data and not just momentary values.

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

I didn't think single file restore was supported with VBB backups?

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

Depends if you use dedupe - see the manual

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

Have another problem now.

NDMP backup seems to go wrong when a backup job hits the end of tape.

Have EMC looking at it but wondered if anyone had seen a similar problem? Using backup exec 2010 R3.

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

Seems this 2nd issue is caused by both the backup exec server and the datamover both having control of the Media changer which is linked with tape drive 1 out of the two tapes drives we have.

If we un-zone the windows backup server from the tape drives the NDMP jobs run fine but problem is we need to see the media changer for windows backups.

Looks like the solution is to partition the library and use one dedicated tape drive for NDMP and one for windows backups. Not ideal as we need both tape drives for the amount of VNX storage we are backing up within the time window! Probably have to get another tape drive now.

Will update when I get a working solution.

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8 Krypton

Re: NDMP backup performance of a de-duped/compressed file system

A good backup software can handle sharing the library – both drives and changer

The changer only get configured on one backup server – the software will use that to change tapes for all backup servers and NDMP clients.

Who is using a tape drive at a time is regulated by the (master) backup server – and often checked using SCSI reserve

Rainer

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