Re: [Xen-users] Bad experience in mounting a domU disk

[Javier Guerra Giraldez <javier@xxxxxxxxxxx>]

On Wednesday 04 June 2008, Alain Barthe wrote:
> I don't understand how a read-only mount can corrupt a filesystem. Does it
> mean that something is written on the device, even if it is read-only ? Or
> does the read-only mount disturb the regular disk activity that is mounted
> rw elsewhere ?

remember that even a r/o mount uses cache, so if somebody else (the DomU) 
writes to the filesystem, the Dom0 cache will be wrong and inconsistent.  
this inconsistency has been known to hang the r/o domain.

i was surprised that the FS was corrupted on disk, but i guess the Dom0 
process that serves the block device to DomU have it as r/w, but doesn't know 
about DomU's caches.  usually it's OK, but it might have interfered with the 
r/o FS's cache, on the same Dom0.


-- 
Javier

Attachment: signature.asc
Description: This is a digitally signed message part.

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users