I should think that if all Linux instances accessed the disk as R/O, you will not have any problems. However, if one Linux has it mounted in Write mode, then you could run into logical inconsistancies. That's because Linux, like all UNIXes, heavily buffers disk I/O and defers writes. This means that meta-data (directory entries and inodes) could be written before the actual data is written. If another image tries to read, then the data it reads is garbage. As I recall AIX had a GFS (Global File System) which could do this. And if Linux ever implements "raw" disks, this might be possible. Make sure that the MDISK is LINKed as RR and that the fstab mounts the disk as RO.
-- John McKown Senior Technical Specialist UICI Insurance Center Applications & Solutions Team +1.817.255.3225 > -----Original Message----- > From: Nix, Robert P. [mailto:[EMAIL PROTECTED]] > Sent: Thursday, August 15, 2002 3:46 PM > To: [EMAIL PROTECTED] > Subject: Can Linux disks on VM be shared read-only? > > > I'm trying to break up a RedHat Linux image so that some of > the major pieces of software reside on their own disks, with > the thought of sharing them as read-only minidisks between > several images. I had a problem during the install, and have > called the IBM support center about it, but in the process of > discussing the problem, when I told him my ultimate > intentions, his response was Oh, you can't do that. It's not > supported; you have to use NFS for that." > > This really took me by surprise, because, unless Linux just > flat won't work with a read-only disk, I'd think that'd be > the way to share things... I mean,... It's VM, right? Why > incur the overhead for NFS when you could just read the > minidisk directly. And one image wouldn't really even know > the other image was sharing the device... > > Am I way off base? > > ---- > Robert P. Nix internet: [EMAIL PROTECTED] > Mayo Clinic phone: 507-284-0844 > 200 1st St. SW page: 507-255-3450 > Rochester, MN 55905 > ---- > "In theory, theory and practice are the same, > but in practice, theory and practice are different." >
