Daniele Palumbo wrote:
> On Tuesday 16 January 2007 01:28, Javier Guerra wrote:
>> but, you could also: (**DANGEROUS**)
>> 1) keep mounted ro in all DomUs
>> 2) mount rw in Dom0
>> --- as soon as you do that, all DomUs are unstable!! ---
>> 3) modify in Dom0 (pray that DomUs don't crash!)
>> 4) umount from Dom0
>> 5) remount on all DomUs (still ro)
>>
>> the point is that the 'r', 'w' or 'w!' flag is only checked at DomU
>> creation time; if at that moment the block device isn't mounted rw by
>> anybody (including Dom0), it will work. later, you could mount it behind
>> Xen's back (and risk all Dom0s, of course)
>
> First of all, thanks for the reply.
>
> but, which is the difference between that approach with "w!" (saying that all
> domU's will mount only ro) and the above?
>
> domU's will became unstable (strange, i figured out only files missing, as i
> think it should be) in the same way, and also (saying that i have "bad guys
> playing with my domUs) i can have a data loss.
>
> so, again, why is not "r!" a valid flag?
Because it's a retarded idea. Hopefully for the last time:
r - Export read only: A single mounter, or multiple mounters, will all
mount read only.
w - Export writable: A single host will mount it writable.
w! - Force writable export: You really know what you're doing because
you're probably using a cluster filesystem and you have multiple
mounters with possible writers, and the filesystem can handle it without
shitting the bed.
r! doesn't make sense. Either mount all of them read only, use w! with
a normal filesystem and suffer the consequences, or use w! with a
cluster aware filesystem.
--
Christopher G. Stach II
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