[Users] Recommended file system?

Markus Stockhausen stockhausen at collogia.de
Wed Dec 18 06:59:20 UTC 2013


> Von: users-bounces at ovirt.org [users-bounces at ovirt.org]" im Auftrag von "Blaster [blaster at 556nato.com]
> Gesendet: Mittwoch, 18. Dezember 2013 06:24
> An: users at ovirt.org
> Betreff: [Users] Recommended file system?
> 
> Any recommended file system to use to hold VM disk images?  EXT4? BTRFS(disable COW I assume?)?  ZFS? XFS?

Hello,

from my point of view I would say do it as you like 
and use the filesystem you are comfortable with.
Maybe to aspects that should be mentioned. 

1) We use a custom build Ubuntu NFS Server with XFS. 
When we evaluated PROXMOX we noticed timeouts 
during creation of QCOW2 images. The simple solution
was to change allocsize setting from some "insane high
in internet found recommendation" to 16M. So if your
VM writes a block into a empty disk area you only 
allocate the surrounding 16M.

2) COW of BTRFS could be a good idea especially if you 
go with RAID5/6.  Even using Hardware RAID. Lets
assume you have a lot of VMs. All of them writing some
kind of data somewhere onto the disks. If each piece is
to small for a full stripe write you run into a read modify
write cycle. Consuming much more IOs. With COW
all this data may be written into one continuous block.
(Netapp sometimes shows quite high write ops, because
their WAFL works similar).

Markus

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