[pve-devel] Default cache mode for VM hard drives

[Alexandre DERUMIER]

About windows virtio driver,

seem that fua (flush) was not correctly implemented until .82 release

https://github.com/YanVugenfirer/kvm-guest-drivers-windows/commit/d7d34714f216cc3291c14427820e781eeb2d5668
https://bugzilla.redhat.com/show_bug.cgi?id=837324

But public virtio-win driver is .81 currently

https://alt.fedoraproject.org/pub/alt/virtio-win/latest/images/bin/

----- Mail original ----- 

De: "Stanislav German-Evtushenko" <ginermail at gmail.com> 
À: "Dietmar Maurer" <dietmar at proxmox.com> 
Cc: "Alexandre Derumier" <aderumier at odiso.com>, pve-devel at pve.proxmox.com 
Envoyé: Mardi 18 Novembre 2014 19:51:18 
Objet: Re: [pve-devel] Default cache mode for VM hard drives 




On Tue, Nov 18, 2014 at 9:45 PM, Dietmar Maurer < dietmar at proxmox.com > wrote: 


> So this is a DRBD bug? 
> 
> Lars doesn't see this as a bug. See also says that software raid behaves in the 
> same way 

IMHO, software RAID is also buggy unless you disable write cache inside drives. That is 
why we never recommend software raid.. 




That's also true. High-end hardware raid controllers (at least Dell ones) do not use (disable) drive caches by default otherwise they wouldn't survive power cut offs.