-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 It is okay to do concurrent mounts if _all_ of the mounts are RO, right? I frequently have many VM's mounting the same DVD iso (RO, of course). Should I be anticipating disaster? David King Goshen College ITS davidwk@xxxxxxxxxx 574-535-7726 On 02/04/2011 05:14 AM, Daniel P. Berrange wrote: > On Fri, Feb 04, 2011 at 04:29:35AM -0500, Dale Amon wrote: >> I suspect the answer is no, as the very idea makes >> my head hurt, but a confirmation would be nice: >> >> Am I correct in assuming that it is a very bad idea >> to mount a physical disk on both the physical machine >> and on a hosted VM at the same time? >> >> I can imagine getting away with it if one were RO, but >> not otherwise. > > Even readonly is not safe. If the host OS has a RO mount > and has partial FS metadata cached, then the guest OS > writes to the FS, this might invalidate the host metadata > and potentially confuse the host OS enough that it would > crash if you're unlucky. > > If you want safe concurrent mounts then you need a clustered > or network filesystem. You can also use libguestfs for readonly > access to live guest disks (still has the potential problem I > mention above, but libguestfs runs in a VM so it avoids any > risk to your host OS) > > Daniel -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk1P+jQACgkQH+/Vg7DylXYz4gCcD2+/J85sjqGYKKieDledchg5 pAkAn2xxzjuPld7mf8zc1taNiPIC/ZrL =y66D -----END PGP SIGNATURE-----
