[pve-devel] Fwd: Re: recommanded cache setting for rbd image

[Stefan Priebe - Profihost AG]

Am 06.11.2012 08:39, schrieb Alexandre DERUMIER:
> Yes, it's safe, in the meaning of "you can break your filesystem".
>
> But you can loose last x seconds of writes if case of powerfailure.
>
> also, you need a linux kernel > 2.6.37, or barrier=1 in your fstab for kernel < 2.6.37
I have ;-)

> and for windows, you really need lasts virtio driver, which can handle writeback correctly.
I don't use windows ;-)

> (Note that cache=none is the same behaviour, you don't have cache on your host, but you always have cache on your disks).
> If you really don't want to loose any write, go to cache=directsync or cache=writethrough, a fsync is done for each write. (so you are sure that all caches (host,disk,raid controller) are flushed for each write)

To me the same functionality like normal SATA disks with cache would be 
fine / ok.

Stefan