> On 27/08/2007, at 12:36 AM, Rainer J.H. Brandt wrote: > > Sorry, this is a bit off-topic, but anyway: > > > > Ronald Kuehn writes: > >> No. You can neither access ZFS nor UFS in that > way. Only one > >> host can mount the file system at the same time > (read/write or > >> read-only doesn't matter here). > > > > I can see why you wouldn't recommend trying this > with UFS > > (only one host knows which data has been committed > to the disk), > > but is it really impossible? > > > > I don't see why multiple UFS mounts wouldn't work, > if only one > > of them has write access. Can you elaborate? > > Even with a single writer you would need to be > concerned with read > cache invalidation on the read-only hosts and > (probably harder) > ensuring that read hosts don't rely on half-written > updates (since > UFS doesn't do atomic on-disk updates). > > Even without explicit caching on the read-only hosts > there is some > "implicit caching" when, for example, a read host > reads a directory > entry and then uses that information to access a > file. The file may > have been unlinked in the meantime. This means that > you need atomic > reads, as well as writes. > > Boyd > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discu > ss
It's worse than this. Consider the read-only clients. When you access a filesystem object (file, directory, etc.), UFS will write metadata to update atime. I believe that there is a noatime option to mount, but I am unsure as to whether this is sufficient. my 2c. --Dave This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
