On Mon, 2006-08-07 at 16:09, Ron Johnson wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Scott Marlowe wrote: > > On Mon, 2006-08-07 at 15:18, Ron Johnson wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- > >> Hash: SHA1 > >> > >> Scott Marlowe wrote: > >>> Oh, I see where you were headed. > >>> > >>> I've found a bit here and there googling about for multiplex and tar, > >>> and found an IO:Multiplex module for perl. > >>> > >>> I don't see why someone couldn't make use of it to create some kind of > >>> system where you'd do: > >>> > >>> pg_dump dbname | perl mulitiplexscript device1,device2,device3,devicen > >>> > >>> No need for postgresql to support it directly. Restoring would likewise > >>> just be a reverse operation. > >> Interesting. Many thanks. Scary though that it hasn't been touched > >> in 30 months. > >> > >> With multiple SCSI cards, each with it's own tape drive, this > >> immensely speeds up the backup operation. > > > > Yeah, I read the description, and I think it's just a fancy name for > > tee. sigh. Not REAL multiplexing, but stream duplication. > > This is where a multi-threaded pg_tapedump would be more effective, > since it would be able to, for example, have 4 threads reading > (different parts of) the database and writing to 4 separate tape drives. Actually, I kinda prefer the idea of creating multiple streams using something like RAID, where if you have two streams, it's a mirror, if you have three or more then you rotate around a parity stripe like RAID 5. Then, any error on any one tape drive could be recovered. Veritas has something like that for tape drives. Heck, the more I think about it, the more I think it would be an interesting project for a device driver that was like /dev/mdt or something, and re-used the md libs from the hard drive universe. Attach X tape drive, put in a bunch of tapes, and just pg_dump > mdt0 and you're backing up. Restore the other way around.
