Synthetic backup - Extremely slow

[Jocke_Bryttmar]

Hello,

We are currently evaluating the Advanced Disk backup option. We want to make our backup window smaller, so the synthetic backup seemed perfect.

However, as it seems this will not be an option we can use. It is actually slower, MUCH slower, than our regular backups. The reason seems to be the configuration option called "collect additional information" that is mandatory on synthetic backups. Before every selection, the backup job first scans the file system to find changes such as renamed folders etc. This scan takes literally forever before the actual backup begins.

Even one of the really small selections in the backup job, containing only 4 folders and about 18MB data, takes 40 minutes to scan. Once the backup starts it only takes a second or so, so the actual backup speed is normal.

Our synthetic incremental backups take 4-5 times longer than a normal incremental backup. This can't be right.

Am I doing something wrong? Does anyone else have this problem? Any ideas?

Regards,
Jocke

[Harry_Dunn]

We are having the same problem.

When we create a policy that contains Full, Incremental and synthetic jobs it requires us to tick "collect additional information for synthetic backup" after this box has been tick and we run either a incremental or full job from the policy it will sit there pre scanning for 40 minutes before backing up any data. The scan always takes 40 minutes regard less of the amount of data that we asked it to backup.

After an un-installation of backup exec and removal of any files that had been created during the backups. We re-installed the software and re-setup the Policy containing the same jobs backing up the same data. Now every time we run a job the job engine will stop half way through the pre scan.

This only happens when "Collect additional information for synthetic backup" is ticked. Backing up the same data using a policy that doesn't contain a synthetic job works fine.

EDIT: We are still in the testing stages and the amount of data used so far has only ranged 20MB - 50GBMessage was edited by: Harry Dunn
Harry Dunn

[Jocke_Bryttmar]

In my case, a very small selection took 40 minutes to scan. Other large selections, containing thousands of folders, take hours.

A normal full backup (not using a synthetic policy) takes about 26 hours. The amount of data is around 900GB. A synthetic incremental backup takes almost 40 hours, even though only 120GB is backed up.

In other words, running full backups every day would be faster than using synthetic backups.

This makes synthetic backups and the Advanced Disk Backup option completely useless.

Does anyone from Veritas have a comment about this? Is this normal behaviour? Is Synthetic backups simply not recommended when you have a huge folder structure?

Regards,
Jocke

[Peter_Ludwig]

Jocke wrote:
> In other words, running full backups every day would be faster than using synthetic backups

I have not tried then up to now, but my problem is taht I back up several remote sites to a central backup server.

If synthetic backups could reduce the load on the leased lines, it would be nice.

I'm wondering if the main work is done by the agent or the backup server.
If only checksums or similar go over the line it should work for me.

greetings
Peter

[Deepali_Badave]

Hello,

Are you getting any media related alerts during the backup?

Are there any errors in the event log?

If antivirus service is running during the backup job, stop it for test purpose and then verify the result.

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