Differential file level backups with VCB and Netbackup 5.1

[dinny]

Hiya,

I am successfully using VCB with Netbackup 5.1 to backup full VMs and to backup file level data for Windows VMs.

I have found a strange problem with differential file level backups for Windows VMs though.

I wondered if it was a known issue - and if so whether anyone had found a work around?

I have amended my Netbackup client to use timestamps rather than the archive bit and I have made sure that the Change Journal in incrementals[/i] setting is not enabled on the Netbackup client.

If I use a backup selection that specifies a subdirectory on a partition - something like:

c:\mnt\vm1.fqdn.com\letters\C\program files\

Then it all works as expected. If I do a full backup initially, then subsequent cumulative incremental backups only backup files in the program files[/i] directory or its subdirectories, that have an amended timestamp .

If however I use a backup selection that specifies a whole drive letter/partition like:

c:\mnt\vm1.fqdn.com\letters\C\

Then the initial full backup backs up all the files as expected - but all subsequent cumulative incremental backups also backup every single file - not just those with different timestamps.

As most people would presumably want to backup at the drive letter level 99% of the time - this seems to force people to in effect do full file level backups on a daily basis.

I have tried it on more than one VM and get the same results.

Has anyone else come across this?

Dinny

[pcomo]

Hi,

same problem with differential backup using Netbackup 6MP4.

Strange.

Let me know if you are more information.

Thanks.

[dinny]

Will do,

I've had a call in with VMware for over 3 weeks - they are waiting till they can get a testbed together to look in to it further.

I suspect that it is probably related to the way that Netbackup handles the VCB mount point - so I would guess it will likely be something that Veritas and VMware have to work on together to resolve - so I'm not holding my breath for a timely response....

Dinny

[ScottHolman]

Differential/incremental backups only seem to work if you dig down deeper into the directory structure.

For instance:

A policy backing up d:\mnt\server.fqdn.com\letters\D will not work as an diff or inc.

Whereas, a policy backing up d:\mnt\server.fqdn.com\letters\D\Data will work. I've tested this and it does work.

It's something to do with the mountpoint being created each time a backup is run. Each time the backup is executed the mountpoint has a different timestamp from the previously created mountpoint.

I agree we should be able to backup from the mountpoint. It's not that much of a problem for me at the moment, as I never have much in the root of a data drive & my system drives are only ever backed up in a weekly FullVM.

Hope this helps.

[dinny]

Thanks Scott,

I suspect you are correct.

So far the only answer I've had from Support is that they think it might be a known problem - and they are still looking in to it.

I suspect that it does relate to the timestamps on the mountpoint - perhaps if they are different at the top level, then VCB never bothers to check the lower ones - unless the backup path specifically refers to the lower level directory?

I agree - I can work round it by doing several lower level backups - but hopefully they will fix it in the next VCB patch/release?

Dinny

[jpeppas]

If trying to backup the filesystem from the root and it has a "bad" date (some times a corrupt attibute might show up as a date in the future), then incremental's based on timestamps ignore the incremental request and do a full backup.

Now, as far as VCB is concerned, when the backup finishes, the folder that hosts the snapshot is deleted. Next time the file system is mounted, the timestamp of that folder (aka the "root" of the filesystem) is NEWER that the last backup, so it thinks' that ALL the filesystem has changed.

I have run into this in physical enviroments (a windows FS had a "bad" date on the root and it could not do incrementals with timestamps).

I have also seen this problem when backing up snapshots (mounted on a backup server) of physical machines on a SAN enviroment.

If VCB did NOT delete the mount point folder, then it might bupass the problem. Unfortunalty, if the folder is present, the script fails.

Jim

[njramos · Accepted solution]

Hi,

I puzzled with the same questions I saw within this forum.

The size of a full backup is the same as the full backup if you use a selection that looks like:

e:\mnt\svr1.domain.com\letters\ or e:\mnt\svr1.domain.com\letters\C

If the selection path is, like e:\mnt\svr1.domain.com\letters\C\Program Files the incremental will work correctly an result in a smaller backup

In a dynamic environment this will result in folders witch are not back upped.

After some testing and trying I find a configuration that isn’t perfect but allow us to make a incremental backup and doesn’t need to much tracking of the changes. Mine selection looks like this:

e:\mnt\svr1.domain.com\letters\C\[b]* (insert manually)

After a full backup the incremental backup does only backup the changed files and folders.

Only when a drive is added (D for example) the selection in the policy must be altered.

Use the same backup policy for both the full and the incremental backup. Create in this policy multiple schedules (full and incrementals). This configuration worked for us

Gr Nelson

[dinny]

Interesting,

VMware Support - did finally acknowledge that it is "a known bug" earlier this week.

I'll try adding a "*" to the end of the path...

Thanks

Dinny

[dinny]

Hiya,

Just had chance to run a test.

Amending my backup selection from:

.....\letters\D\

to

.....\letters\D\*

worked like a dream.

Just the changed files were backed up.

Great suggestion njramos

I'll mark it as correct now and award the points.

If I hear that the bug is eventually corrected by VMware - I'll post on this thread again.

Dinny

[njramos]

Hi dinny,

thank u for the points.

please to help.

grtz Nelson

[dritschel]

I'm trying to backup C:, D:, E: and F: drives using a VCB file-level backup. If I put all 4 in a NetBackup Policy, only one completes. The others fail with an error 73.

If I backup all 4 drives by just putting C:\mnt\tstesx30-vm08.nam.nsroot.net\letters\ in a NetBackup Policy, the full works fine but the incremental is equivelent to a full backup.

I've tried variations of adding \* on the end of the backup selection with not luck.

So, is there a solution to backing up multiple disk drives, and being able to run incremental backups?

[trpzit]

A quick note; I'm using Veritas 6.0mp4 and VCB 1.03. I just tested backing up multiple drives through a single policy in this scenario and it worked absolutely correctly; backup selections looked like:

c:\mnt\myvmname\letters\C\*

c:\mnt\myvmname\letters\D\*

It seems that this case works now... it's a real shame that VMware didn't bother to relnote it or update their documentation.

--Ross

[SchalkAlbertyn]

Hi have a similar problem using NetBackup 5.1 Media Pack 3

I tried doing a test on the following folder:

c:\Test backup

Firstly I setup a policy that does a full backup of this folder and then another policy to do differential backups of this folder.

The folder structure looks like this:

c:\Test backup

- Folder 1

- Folder 2

If I specify my backup selection as:

c:\Test backup\*

It backs up all the files under the c:\Test backup folder. The Folders underneath gets backed up as a full backup.

It does not only backup changed files under these folders listed under c:\Test backup. It does backup only the files[/b] under c:\Test backup as differential. This leaves me to select each folder with a * after each of them.

Example:

c:\Test backup\*

c:\Test backup\Folder 1\*

c:\Test backup\Folder 2\*

Can anyone help with this issue?

I don’t want to specify each folder with a *.

[dinny]

Hiya,

That has always worked OK for me (without the *)

See my first post:

I have amended my Netbackup client to use timestamps rather than the archive bit and I have made sure that the Change Journal in incrementals setting is not enabled on the Netbackup client.

If I use a backup selection that specifies a subdirectory on a partition - something like:

c:\mnt\vm1.fqdn.com\letters\C\program files\

Then it all works as expected. If I do a full backup initially, then subsequent cumulative incremental backups only backup files in the program files directory or its subdirectories, that have an amended timestamp .[/i]

I doubt the "*" is the problem though - but you could try without...

Have you definitely made sure that the "Change Journal in incrementals setting" is not enabled on the Netbackup client?

Dinny

[njramos]

H,

I noticed in your post that you are using two different policies.

If you want this to work, you need to use one policy. Make in this policy two schedules.

The first schedule does the full back-up

The second schedule does the incremental.

Greetz Nelson

[Pootie_Tang]

Be wary of the solution:

After some testing and trying I find a configuration that isn’t perfect but allow us to make a incremental backup and doesn’t need to much tracking of the changes. Mine selection looks like this:

e:\mnt\svr1.domain.com\letters\C* (insert manually)

After a full backup the incremental backup does only backup the changed files and folders.

I've found when using Backup Exec v12.5, the job log will show what looks like a proper Byte Count, but the only files getting backed up are files whose name begins with the letter preceding the *. In the case above, all files beginning with the letter C. Once created, the selection list entry will appear as:

e:\mnt\svr1.domain.com\letters\c* /SUBDIR