Veeam Zip Doubling Snapshot Size

[natefinley]

I am fairly new to Veeam and I am currently using the free version of Veeam to do full backups of my VMs. Currently, I'm using the Veeam Zip feature to do a full backup. In recent days, one of my VMs has started to double the size of the snapshot being created when it begins the backup process. As a result, it's also doubling the size of the backup file that it's creating. Nothing has changed on my end in terms of setup, and I haven't been able to resolve this through any methods of my own. Does anyone have any idea where to start with troubleshooting this issue?

Nate

[Gostev]

In recent days, one of my VMs has started to double the size of the snapshot being created when it begins the backup process.

I don't understand what you are saying here. Snapshot file is always created empty, and then it grows with time... that's just how VMware snapshots work. How "empty" can be "double the size"? Snapshot stores all the changes made to the virtual disk by running VM, it exists for the duration of backup only, but keeps growing as backup progresses. Do you possibly mean it grows double the size?

[natefinley]

Sorry, let me see if I can explain in more clear terms. The VM I am having trouble with is thick provisioned for 160 GB. As most, there is about 75 GB being used. Previously, I was using VeeamZIP to do a full backup and the back would be around 35-40GB. Now, for some reason, when the VeeamZip job starts off, it is reading 155GB used on the VM, or double the actual amount of data. When the VeeamZip job is finished, I'm ending up with a backup file of about 90+ gigs. The total amount of data on the drive is still around 75GB, but Veeam is reading 155GB used. Is there any way to resolve this?

[Gostev]

Your numbers do not match up, may be you are missing something. But this is not the issue we can troubleshoot over the forum post, as this requires debug logs review by the devs.

[foggy]

Is there a chance that some data was written and then deleted from this VM creating a large number of "dirty" blocks (unused by the OS but not zeroed due to how NTFS works), which are read during backup?

[Gostev]

In that case, vSphere would not report 75GB used. Unless Nathan meant in-guest disk space readings, in which case you are correct of course, this would be the reason.