[libvirt] [PATCH] set cache=off on -disk line in qemu driver if <shareable/> (but not <readonly/>) is set.

Dor Laor dlaor at redhat.com
Mon Nov 3 16:37:45 UTC 2008


Daniel Veillard wrote:
> On Sat, Nov 01, 2008 at 06:20:27PM -0500, Charles Duffy wrote:
>   
>> As cache=off is necessary for clustering filesystems such as GFS (and  
>> such is the point of shareable, yes?), I believe this is correct 
>> behavior.
>>
>> Comments?
>>     
>
>   Yes that sounds right, if shared over network we should not cache
> locally in the OS,
>
>     applied and commited,
>
>       thanks !
>
> Daniel
cache=off should be the default case (or the similar O_DSYNC case).
cache=on should only be used for temporal usage and not really 
production data.
It's just unsafe to use caching if you data is important to you.
It's a hot issue in the qemu mailing list.

Cheers,
Dor
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