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Re: [Xen-users] How to share data between guest domains

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] How to share data between guest domains
From: "Todd D. Esposito" <Todd@xxxxxxxxxxxxxxxx>
Date: Sat, 18 Mar 2006 21:00:28 -0600 (CST)
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On Sat, March 18, 2006 20:19, Javier Guerra said:
> would that work over a shared image/LVM partition? i mean, using the same
> backing store for two domU's would be similar to a network/SAN shared
> block
> device.
>
> i know xm is supposed to forbid it, but is there any way to override the
> check
> for some devices?

That sounds an awfully bad idea.  Most (all?) non-networked filesystems
assume, correctly, that they have complete control over the filesystem
data AND metadata, so they don't need to worry about two processes
updating the same inode, for example, at the same time.  NFS and other
networked systems DO have to worry about that.

However, on that note, I wonder if you could mount the same file system,
say something like /usr, into multiple domU's READ ONLY.  That could
certainly save some trouble when updating applications, etc.  Anyone tried
it?

- Todd


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