[PVE-User] BTRFS...

Gilberto Nunes gilberto.nunes32 at gmail.com
Tue Feb 2 18:24:51 CET 2016


Hi

And what if I work with BTRFS inside the VM???
The FS where VM image lay could be any other FS... Currently, I am use
GlusterFS + XFS.
I need LVM or BRTFS inside the VM, in order to resize disk partition...
And I am between LVM or BRTFS....

2016-02-02 15:10 GMT-02:00 Adam Thompson <athompso at athompso.net>:

> As far as I know, there is still one big problem with BTRFS for Proxmox:
>
> Running a thin-provisioned VM (i.e. QCOW2) on top of a BTRFS filesystem on
> top of a regular spinning-rust HDD produces **extremely bad** performance.
>
> Running the identical system but on ext2/ext3/ext4 produces the expected
> performance you'd get out of an HDD.
>
> Running the BTRFS system on an SSD instead of an HDD works fine.
>
> IIRC, it has something to with the way BTRFS journalling works, such that
> whenever the QCOW2 file had to grow, there was an I/O multiplication effect.
>
> That testing was done in CentOS and Ubuntu, not PVE, but apparently the
> problem is related to the way QCOW2 and BTRFS interact so would be
> persistent across all environments.
>
> Possibly either BTRFS or QCOW2 have fixed this by now, I don't know.
>
> -Adam
>
>
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-- 

Gilberto Ferreira
+55 (47) 9676-7530
Skype: gilberto.nunes36
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