Richard Elling wrote: > I think this is a systems engineering problem, not just a ZFS problem. > Few have bothered to look at mount performance in the past because > most systems have only a few mounted file systems[1]. Since ZFS does > file system quotas instead of user quotas, now we have the situation > where there could be thousands of mounts. Now we do need to look at > mount performance more closely. We're doing some of that work now, and > looking at other possible solutions (CR6478980). > > [1] we've done some characterization of this while benchmarking Sun > Cluster failovers. The time required for a UFS mount can be quite > substantial, even when fsck is not required, and is also somewhat > variable (from few seconds to tens of seconds). We've made some minor > changes to help improve cluster failover wrt mounts, so perhaps we > can look at our characterization data again and see if there is some > low-hanging fruit which would also apply more generally.
The problem is that in order to restrict disk usage, ZFS *requires* that you create this many filesystems. I think most in this situation would prefer not to have to do that. The two solutions I see would be to add user quotas to ZFS or to be able to set a quota on a directory without it becoming it's own filesystem. We've ruled out using ZFS for our systems at this time due to these limitations and the fact that thousands of mounts on a host entail a very long reboot (and the fact that snapshots count toward filesystem quota). Any chance that user quotas will be added in the future? It would go a long way to alleviating this problem. Ideally, snapshots would not count against user quotas if possible. Jim _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
