This is my first dive into unraid, ive been testing it out for a couple of days now. For the most part all the helpful guides here on the forum (ive been lurking alot) and youtube have helped me get situated, but i recently began testing backup and restores and came across an interesting problem that i cant see to find an answer to. So here goes my explanation, maybe someone can help me understand whats going on here. Whatever additional information i may have missed, please ask questions. 

 

VMS are installed on an unassigned device (SSD xfs)

 

1. Installed 3 VM's. (10G, 80G, 100G hd size) . none are fully saturated. total on disk usage = ~75G

2. installed user scripts plugin and this backup method for backing up vm's https://lime-technology.com/forum/index.php?topic=47986

3. Backup successful, restore successful, all booted up fine.

4. Restore of 3 vm's now takes up ~190G.

 

Why would the VM's "balloon" up to full disk capacity now? I understand that i shouldnt be oversubscribing on the storage device, but what am i missing here? I cant seem to find an answer to this.

 

Thanks for your time

 

When originally created the vdisk's are normally set up as 'sparse' files so that unused blocks are not initially allocated space.    The backup/restore process seems to have converted them to standard files so that all their allowed space is now allocated.

 

Is this causing a problem?    You always need to allow for the full space to potentially be used if you do not want VMs to start failing unexpectedly.

I made a suggestion for dani to use the sparse option during rsync but he's not been very active lately, you can make it sparse again by restoring with cp, eg:

 

cp --sparse=always /path/to/backup.img /path/to/vdisk.img

@itimpi - nope its not causing any problems. I have more than enough drive capacity, i just didnt understand the dynamics to it.

 

@johnnie.black - thanks for the cp command. backup and restore work perfectly now.