is it safe to disable atime enable relatime for all datastores with qcow2/raw/vmdk/vzdump files ?

[RolandK]

hello,

as i found that atime can cause pathological slowness ( https://forum.proxmox.com/threads/w...source-disks-when-moving-virtual-disk.123639/ ) , i'd like to set atime=on and relatime=on on all my datastores and also on the backup target where vzdumps being written to.

i know that relatime is being ok for pbs.

is this safe to do for vm and vzdump datastores/directories ?

regards

 

[RolandK]

anybody here using atime=on or atime/relatime=on with vm or vzdump datastores in production ?

 

[janssensm]

Hi, I was wondering too as I saw some scattered discussions on using atime and relatime on zfs datasets. And I assumed this thread is about zfs as your linked post is about zfs datasets .

My pve host (pve-manager/7.4-3/9002ab8a) was installed prior to pve 7.x and zfs rpool dataset has defaults from install time:
relatime=off, atime=off
The other pools were created manually via cli, they got other defaults (from zfs I assume):
relatime=off, atime=on

There is this commit for the pve installer:
https://git.proxmox.com/?p=pve-installer.git;a=commit;h=9bc6376d6aab098134c0dec3ca6567dfb964267d

zfs create: default to relatime
like other FSs do already.

So I did a test install from latest proxmox-ve_7.4-1.iso and installed it with root on a zfs mirror pool via the guided setup.
It end up with zfs rpool dataset:
relatime=on, atime=on
So, I think this would answer your question I guess, as the default pve install has these settings.
Manually created zfs pools still default to relatime=off, atime=on.

Maybe proxmox staff could advise what defaults currently should be used (for all pools) and/or maybe hint for that in the admin docs.

 

[fabian]

yeah, PVE itself doesn't really care about atime anywhere (important) AFAIK.