VMware Tools Quiesence and pre-freeze/post-thaw script

[adam900331]

Hy!

I am confused about the VMware Tools Quiesence and pre-freeze/post-thaw script using when backing up a Linux VM which has MariaDB database. The aim is to create transactionally consitent backup.

There is a backup job which is contain some Windows VM and Linux VM. I know, the in this case I enabel the VMware Tools Quiesence and the AAIP both during the job settings:
https://helpcenter.veeam.com/docs/backu ... ml?ver=120

But in real I didn't select the VMware Tools Quiesence. I only enable the AAIP and select the VMs which I would like to create consitent backup, it include some Windows VM (DC) and some Linux VM. I defined pre-freeze and post-thaw script in Liunx VMs settings. The scripts works well during the backup, it shows in the backup logs.

But my question: Whyt is the advantage if I select the VMware Tools Quiesence option? And Why? What is the disadvantage if I don't enable the VMware Tools Quiesence option? I don't understand it, beacaues the backup is working well with Windows and Linux VM ins the same job without VMware Tools Quiesence.

Thanks.

[Mildur]

Hi Adam

If backup jobs are successful with AAIP in your environment, then you don't need to change anything in your configuration.

Our recommendation is to enable VMware Tools quiescence if you have Linux VMs in the job. Even if it may never be used because AAIP worked for all VMs in the job:
1) The backup server first tries to use AAIP. If AAIP is successful for all VMs, it won't use VMware Tools quiescence.
2) If AAIP cannot be used for a VM or AAIP is disabled for this VM, the backup server will use VMware Tools quiescence to prepare this VM.
Combined Approach

Keep the configuration as it is, if you don't see any issues with it. As long as you have at least AAIP enabled and working successfully for all VMs, you are all good

Best,
Fabian

[Andreas Neufert]

I disagree with this approach.

VMware Tools quiescence processing does the following in Linux
1) run pre freeze scripts (if you added some in the Linux filesystem) (and later post-thaw script).
2) start file sync operation if you have enabled this option manually

So by default it does "nothing" but the additional processing is overhead on the VMware management and could go wrong and fail. It is very hard for a Veeam admin to find root causes when something goes wrong as you would need to analyze VMware logs and sync it manually with our logs to understand them.

The filesystem sync driver is not compatible with most of the databases as it holds the IO on the filesystem (which crashes many DBs). So I would not recommend to enable it.

As Fabian wrote if you enable the Veeam (AAIP) Guest processing it will use it by default and then falls back only to VMware tools quiescence for VMs that are not enable with Veeam AAIP. But as VMware Tools quiescense does nothing (by default) and is heavy on things that could go wrong I would not do this at all.

Veeam script usage is way better to diagnose when it goes wrong (just look at Veeam logs), so I would suggest using them instead of VMware Tools based pre-script processing at any time.

[adam900331]

Thanks, so in short the VMware Tools Quiesence option is not reccomend to use it, isn't it?

[Andreas Neufert]

Correct, only if you have no other options.

For Windows, only if you do not get (for example as hoster) access to the guest credentials and want to perform consistency with VSS or use it for pre/post scripts.

For Linux, only if you do not get (for example as hoster) access to the guest credentials and you would like to use pre and post scripts (as file sync driver usually causes more harm than it does good with unknown environments).

[Andreas Neufert]

Following up here, we have updated our documentation to be inline with my recommendation.