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What happens if files are created/modified during backupexec backup operation?

Created: 28 Jul 2013 | 9 comments


We use combination of Veeam / backup exec in our environment.

Veeam is used to do image backup of VMs, and backup exec copies these files to tape.

What happens if Veeam backup window and backup exec windows overlaps? 

If new file is created or exisitng file is modified(reverse incremental) during while backup exec backup is running, how does backup exec handle this?

Anyone has experience with this?



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pkh's picture

I believe BE will do a snapshot of the volume and back this up.  Whatever changes to the volume after the snapshot will not be reflected in the backup set.  It would be better if you make sure that the two backups do not overlap.

michaelshin01's picture


I'm not using AOFO.

Would backup exec lock the file when it's backing it up, hence Veeam backup will fail due to veeam unable to transform full backup file into reverse incremental file?

pkh's picture

You should be using AOFO when backing up files.  Otherwise, BE would have problems backing up opened files.

Colin Weaver's picture

VSS snapshots may be triggered automatically, without AOFO being enabled (depending on what you backup and the operating system on the machine being backed up)

Also as pkh has already mentioned, it is not good practice to run two backup products against the same backup sets at the same time and even if you make them run separately you may still have problems with databases and log sequence numbers if you use multiple backup products on the same system

You'd have to check with Microsoft but once a VSS snapshot is taken that covers a file I am not aware that the file remains locked as such the only fiels that Backup Exec should be locking are its own program binaries and logs.

Kunal.Mudliyar's picture

You dont want that kind of overlap to happen either one will have issues.

if the BE is backing Veeam cant modify veeam is dumping the data BE might retain the old copy and not the modified one.

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michaelshin01's picture

Thanks all for the replies.

For AOFO, i'm using backup exec to copy Veeam backup files to tapes, hence if the file is being modified by Veeam, there is no point snapshoting those files, as these files won't be consistent.

Also, I'm not running Veeam / Backupexec against same target.

As mentioned above, Veeam backs up all the VMs to backup repository, and backup exec job is configured to copy files in Veeam repository to tape.

My client insist we run full tape backup everyday and move daily tapes to offsite, and due to this requirement, we're backing up full Veeam repository, which is about 4.5Tb, to tapes everyday.

Tapes are replaced at 12pm, and Backupexec job starts at 1pm.

This job runs for 12~14 hours, and Veeam backup usually starts at around 1am.

I wasn't sure what will happen if Veeam starts writting more data / modify existing backup files when backup exec was still copying those files to tape.

CraigV's picture run the risk of 1 of the jobs having corrupt data. it might not happen, but always err on the side of caution.

Have you tried to tune your tape drive? Check pkh's article around this:


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Donald Eady's picture

Agreed with all previous statements ... Additionally i  would expect to see failures on one or the other as the writers used durring snapshot process would be busy/being used by the which ever software gets ahold of them first. 

I hope this posting was helpful


pkh's picture

As they say, the proof is in the pudding.  Even if your backups are successful, you should try to recover your servers by restoring the Veeam backups from tape and then doing a restore from the Veeam backups.  This is the only sure way of telling whether your backup scheme works.