> I have budget constraints then I can use only user-level storage. > > until I discovered zfs I used subversion and git, but none of them is designe > d to manage gigabytes of data, some to be versioned, some to be unversioned. > > I can't afford silent data corruption and, if the final response is "*now* th > ere is no *real* opensource software alternative to zfs automatic checksummin > g and simple snapshotting" I'll be an happy solaris user (for data storage), > an happy linux user (for everyday work), and an unhappy offline windows user > (for some video-related activity I can't do with linux).
Note that I don't wish to argue for/against zfs/billtodd but the comment above about "no *real* opensource software alternative zfs automating checksumming and simple snapshotting" caught my eye. There is an open source alternative for archiving that works quite well. venti has been available for a few years now. It runs on *BSD, linux, macOS & plan9 (its native os). It uses strong crypto checksums, stored separately from the data (stored in the pointer blocks) so you get a similar guarantee against silent data corruption as ZFS. You can back up a variety of filesystems (ufs, hfs, ext2fs, fat) or use it to to backup a file tree. Each backup results in a single 45 byte "score" containing the checksum of root pointer block. Using this score you can retrieve the entire backup. Further, it stores only one copy of a data block regardless of what files or which backup it may belong to. In effect every "full backup" is an incremental backup (only changed data blocks and changed or new ptr blocks are stored). So it is really an "archival" server. You don't take snapshots but you do a backup. However you can nfs mount a venti and all your backups will show up under directories like <machine>/<yyyy>/<mm><dd>/<filesystem>. Ideally you'd store a venti on RAID storage. You can even copy a bunch of venti to another one, you can store its arenas on CDs or DVD and so on. It is not as fast as ZFS nor anywhere near as easy to use and its intended use is not the same as ZFS (not a primary filesystem). But for what it does, it is not bad at all! Unlike ZFS, it fits best where you have a fast filesystem for speed critical use, venti for backups and RAID for redundancy. Google for "venti sean dorward". If interested, go to http://swtch.com/plan9port/ and pick up plan9port (a collection of programs from plan9, not just venti). See http://swtch.com/plan9port/man/man8/index.html for how to use venti. > I think for every fully digital people own data are vital, and almost everyon > e would reply "NONE" at your question "what level of risk user is willing to > tolerate". NONE is not possible. It is a question of how much risk you are willing to tolerate for what cost. Thankfully, these days you have a variety of choices and much much lower cost for a given degree of risk compared to just a few years ago! _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
