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KeithLowKW
Contributor
Contributor

Multiple backup products over VADP

Hi, would like to check is it possible to have 2 backup products backing up via vSphere VADP using CBT?

A scenario will be backup product A performing full & incremental backup of VMs using VADP, and another product performing VM incremental replication.

Thanks.

5 Replies
mhampto
VMware Employee
VMware Employee

There will be no issues, CBT is designed to handle such usage scenarios as CBT sets a flag number (epoch) each time it backs up.

The first backup starts on a VM and sets an epoch of 1. Next backup starts and looks for changes beyond epoch 1, if there are it sets a new epoch of 2. This continues increment as the backups continue.

When adding another backup product it will query the epoch and compare it to the last one is used, say 1, and now the epoch is up to three.  It will backup the data from epoch 2 and 3 to get caught up.

KeithLowKW
Contributor
Contributor

Thanks. Will you be able to point me to any documentation on this? I would like to understand more.

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cyberpaul
Enthusiast
Enthusiast

Hi Keith,

I would recommend VMware's VDDK guide: http://pubs.vmware.com/vsphere-55/topic/com.vmware.ICbase/PDF/vddk55_programming.pdf

Take a look at the "Backup and Recovery Example" chapter at page 40, which describes the backup process in general. Basically every backup application follows this scenario. In short, it goes like this:

1 Perform full backup

1.1 Create a snapshot and remember the cbtChangeId attribute for each virtual disk

1.2 Backup all data on virtual disks

1.3 Remove the snapshot

2. Perform incremental backup

2.1 Create a snapshot and obtain a list of changed blocks since the snapshot taken in 1.1 using the cbtChangeId from 1.1

2.2 Backup only changed blocks

2.3 Remove the snapshot

Each of your backup applications creates its own snapshots and therefore uses different cbtChangeIds. The CBT technology can deal with this.

However, I would advise against running multiple backups simultaneously as there are connection and other limits in vSphere which you might hit.

Cheers, Pavel

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Vasanthbg
Contributor
Contributor

VADP integrated backup products utilize snapshot to take backups. Each backup operation either it can be full-backup or incremental-backup is independent and will create its own snapshot to do backup. It doesn't matter if its the same backup product or two different backup products will be utilized in here.

If CBT is enabled in this case, for every snapshot if any data change exists then CBT can be utilized to pick only the changed blocks & do incremental backups.

For more information about CBT, use of Change-Id please refer to "Changed Block Tracking on Virtual Disks" in https://vdc-download.vmware.com/vmwb-repository/dcr-public/17aee92f-6920-4675-b03c-8c85de455bb3/eb0d...

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kirhanaraaj
Contributor
Contributor

I tried this in my lab with avamar and veeam backup and here the result that I got

First full Backup started on avamar :- Took 30 mins
Incremental backup :- took 1 min

First full Backup started on veeam :- 30 mins
incremental backup :- 3 mins

Second incremental back on avamar : 1min
Seond incremental backup on veeam : 3 mins

Thrid incremental backup on avamar :- 1 min
Third incremental on veeam :- 3 mins

Fourth Incremental backup on avamar : 1 min
Fourth incremental backup on veeam : 3 mins

So, both avamar and veeam respected the cbt/incremental backups each time it ran.

 

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