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Netbackup Appliance deduplication/re-hydration problem

Netbackup Appliance deduplication/re-hydration problem

Netbackup Master Server Version: 7.5.0.7
Netbackup Appliance 2530, Version 2.5.4
Netbackup Appliance Media Server Version 7.5.0.7

Backup Type: Exchange DB Backup (DAG) with GRT
Client OS/Version: Windows Server 2008 RT, Netbackup


Help! One of our Netbackup appliance hosts Exchange Database backup (DAG) with GRT... Backups do run with good speed and without any issues during normal circumstances... These backups are set to duplicate to tape (managed via SLP), everyweek... As soon as the SLP starts to copy the data from MSDP to tape, the backups' speed becomes haywire and runs extremely slowly.. As soon as I kill off the duplication job, the backups revert to normal again...

Another problem is that, whenever the duplication run the exchange backups fail with error code 24 or 42 (Network Write error or Network Read error).. This doesnt happen during normal backups... Please help on this.

Also, it would be highly helpful if someone could explain de-duplication/dehydration workflow and duplication to tape workflow (via SLP)...

 

1 Solution

Accepted Solutions
Accepted Solution!

Hi OK. In that make sure

Hi

 

OK. In that make sure you're not running backup to the pool while you're duplicating frmo the pool to tape. Also make sure you run very few stream simultaneously for the duplication. I'd keep it between 4-8 depending on your amount of tape drives.

 

I've previously performed tests and found that running more stream just increases the load in terms of processing (rehydration) and your overall performance declines rapidly.

View solution in original post

6 Replies

Hi winter_prince, When you

Hi winter_prince,

When you duplicate a GRT backup to tape , exchange database image gets mounted and processed before it even starts writing to tape (which can tie a tape drive up for quite some time) it will slow down the process .If you do not want to keep the advantage of GRT fromtape , you can disable cataloging .This will 

 

Disabling the cataloging for duplications of Exchange backups using Granular Recovery Technology (GRT)

Unlike a duplication of a backup that uses Granular Recovery Technology (GRT) from tape to disk, duplication of the same backup from disk to tape takes extra time. NetBackup requires this extra time to catalog the granular Exchange information. You can choose not to catalog the granular information so that the duplication is performed more quickly. However, then users are not able to browse for individual items on the image that was duplicated to tape if the disk copy expires.

During the duplication process, NetBackup writes log entries periodically to show the progress of the job.

To disable the cataloging of Exchange backups using Granular Recovery Technology

> On the master server, open the NetBackup Administration Console.

> In the left pane, expand Host Properties.

> Click Master Servers.

> In the right pane, right-click the master server click Properties.

> Click General Server.

> Uncheck Enable message-level cataloging when duplicating Exchange images that use Granular Recovery Technology.

> Click OK.

 

 

DeepS

Your rehydration issues will

Your rehydration issues will be resolved if you upgrade to 7.6.1(.2). There were huge improvements done in that area.

Hi Riaan, Yes, I heard that

Hi Riaan,

Yes, I heard that too... There are future plans to migrate our netbackup environment to 7.6 and then upgrade the appliance version to 2.6 as well... But that wont be anytime sooner though. 

I am currently looking for a possible workaround ...

Hi Deeps, Thanks for the

Hi Deeps,

Thanks for the suggestion... But, unfortunately: we do want to preserve GRT in the tape copy as well...

Regards,
SUGAN P

Currently I am gonna try on

Currently I am gonna try on following options to mitigate this issue:

  • Run the backup without GRT to tape (via SLP) to observe whether the issue re-occurs.. This way, I can confirm if GRT is the root cause for all this.
  • GRT via Granular Proxy host
  • Change Fragment size to "5000" (of the disk storage unit) and observe the backups.

Please let me know if you have any suggestions....

Accepted Solution!

Hi OK. In that make sure

Hi

 

OK. In that make sure you're not running backup to the pool while you're duplicating frmo the pool to tape. Also make sure you run very few stream simultaneously for the duplication. I'd keep it between 4-8 depending on your amount of tape drives.

 

I've previously performed tests and found that running more stream just increases the load in terms of processing (rehydration) and your overall performance declines rapidly.

View solution in original post