BTRFS on ZVOL

C

casalicomputers

Renowned Member
Mar 14, 2015
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Hi there,
I had to create a samba server with shadow copy support, so I needed a fs with snapshot support and I thought to use BTRFS which is well suitable for this purpose (I used it before on bare-metal installations).

Since it's a COW filesystem like ZFS, I was wondering if it could cause issues when used on top of a ZVOL, and if it's a good idea to couple such filesystems. At this time I created the btrfs partition and disabled btrfs cow (nodatacow in fstab).

I'm currently experiencing random issues with host high cpu usage (especially after backups), and I don't know if that could be the cause.

Any experiences to share on this?

Thanks
 
Only to understand you correctly:

You have ZFS on your host and want to use brtfs in your KVM-based VM?

If you use it this way, it is possible but not very fast. The whole ZFS stuff is not visible in your VM and you only see raw storage. You should not enable compression on both, but it should work (technically speaking). The high cpu usage can come from the two systems on top of each other.

I use ZFS on a crypted ZFS volume without a (technical) problem, yet it is very slow indeed.
 
casalicomputers said:
Hi there,
I had to create a samba server with shadow copy support, so I needed a fs with snapshot support and I thought to use BTRFS which is well suitable for this purpose (I used it before on bare-metal installations).

Since it's a COW filesystem like ZFS, I was wondering if it could cause issues when used on top of a ZVOL, and if it's a good idea to couple such filesystems. At this time I created the btrfs partition and disabled btrfs cow (nodatacow in fstab).

I'm currently experiencing random issues with host high cpu usage (especially after backups), and I don't know if that could be the cause.

Any experiences to share on this?

Thanks
Click to expand...

I need to do this, too. How is your experience now a year later?
 
fireon said:
BRTFS on ZFS, what the hell....
Click to expand...

Ist doch machbar oder? Habe bis jetzt sehr viele Samba/BTRFS Fileserver in einer VM deployed. Das ganze bis jetzt halt nur auf ext4 oder LVM Basis. Habe als Hauptstorage 2x Intel NVME SSD's im ZFS Raid1. was moanst?
 
mac.linux.free said:
Ist doch machbar oder? Habe bis jetzt sehr viele Samba/BTRFS Fileserver in einer VM deployed. Das ganze bis jetzt halt nur auf ext4 oder LVM Basis. Habe als Hauptstorage 2x Intel NVME SSD's im ZFS Raid1. was moanst?
Click to expand...
It is of course. But it is not recommend. It is better you use an HW Raidcontroller with big Cache and Ext4, on that on LVM-Thin use your BTRFS.
Is no other filesystem compatible with the shadowcopy feature? Only an idea... but maybe an LXC-Container on ZFS can to that...

English Forum!!!
 
fireon said:
It is of course. But it is not recommend. It is better you use an HW Raidcontroller with big Cache and Ext4, on that on LVM-Thin use your BTRFS.
Is no other filesystem compatible with the shadowcopy feature? Only an idea... but maybe an LXC-Container on ZFS can to that...

English Forum!!!
Click to expand...

Sorry ... the Samba on LCX Container was also on my mind (Shadow Copy through LXC???). But I will tell how it worked out with my BTRFS on ZVOL (4k) worked out :)
 
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