I thought that until a few days ago, a sequence like the following (two nfs servers exporting the same clustered data) on client 1 lock range A through B of file1 (exported from nfs server 1) on client 2 lock range A through C of file 1 (exported from nfs server 2) on client 1 write A through B on client 2 write A through C on client 1 unlock A through B on client 2 unlock A through C would corrupt data (theoretically could be fixed as nfsd calls lock methods http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=fd85b8170dabbf021987875ef7f903791f4f181e) but the more obvious point is that with two nfsd servers exporting the same file data via the same cluster fs (under nfsd), the latencies can be longer and the opportunity for stale metadata (file sizes) and also writes getting reordered is higher. Steve French Senior Software Engineer Linux Technology Center - IBM Austin phone: 512-838-2294 email: sfrench at-sign us dot ibm dot com "J. Bruce Fields" <bfields@xxxxxxxxxxxx> 05/16/2007 11:02 AM To Steven French/Austin/IBM@IBMUS cc Christoph Hellwig <hch@xxxxxx>, akpm@xxxxxxxxxxxxxxxxxxxx, hch@xxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, neilb@xxxxxxx Subject Re: + knfsd-exportfs-add-exportfsh-header-fix.patch added to -mm tree On Wed, May 16, 2007 at 09:55:41AM -0500, Steven French wrote: > Any ideas what are the minimum export operation(s) that cifs would need to > add to export under nfsd? It was not clear to me after reading the > Exporting document in Documentation directory. > > (some users had wanted to export files from Windows servers to nfs clients > files by putting an nfs server mounted over cifs in between - I realize > that this can corrupt data due to nfs client caching etc., as even in some > cases could happen if you try to export a cluster file system under nfsd). What cases are you thinking of? --b. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
