On Tue, May 23, 2006 at 02:34:30PM -0700, Jeff Victor wrote: > * When you share a ZFS fs via NFS, what happens to files and > filesystems that exceed the limits of NFS?
What limits do you have in mind? I'm not an NFS expert, but I think that NFSv4 (and probably v3) supports 64-bit file sizes, so there would be no limit mismatch there. > * Is there a recommendation or some guidelines to help answer the > question "how full should a pool be before deciding it's time add disk > space to a pool?" I'm not sure, but I'd guess around 90%. > * Migrating pre-ZFS backups to ZFS backups: is there a better method > than "restore the old backup into a ZFS fs, then back it up using "zfs > send"? No. > * Are ZFS quotas enforced assuming that compressed data is compressed, > or uncompressed? Quotas apply to the amount of space used, after compression. This is the space reported by 'zfs list', 'zfs get used', 'df', 'du', etc. > The former seems to imply that the following would create a mess: > 1) Turn on compression > 2) Store data in the pool until the pool is almost full > 3) Turn off compression > 4) Read and re-write every file (thus expanding each file) Since this example doesn't involve quotas, their behavior is not applicable here. In this example, there will be insufficient space in the pool to store your data, so your write operation will fail with ENOSPC. Perhaps a messy situation, but I don't see any alternative. If this is a concern, don't use compression. If you filled up a filesystem's quota rather than a pool, the behavior would be the same except you would get EDQUOT rather than ENOSPC. > * What block sizes will ZFS use? Is there an explanation somewhere > about its method of choosing blocksize for a particular workload? Files smaller than 128k will be stored in a single block, whose size is rounded up to the nearest sector (512 bytes). Files larger than 128k will be stored in multiple 128k blocks (unless the recordsize property has been set -- see the zfs(1m) manpage for an explanation of this). Thanks for using zfs! --matt _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
