incremental backups
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From: Richard Kettlewell on 7 Jun 2010 04:12 Richard Kimber <richardkimber(a)btinternet.com> writes: > Richard Kettlewell wrote: >>> The backup medium is a usb external drive. Eventually I would like to >>> only mount the drive for the backup process. Does unmounting >>> effectively disable the usb disk (err powering it down)? >> >> It won't power it down. > > It depends on the drive. Mine spins down and seems to go to sleep > automatically after a certain period of inactivity and I only ever > mount it for backup (or restore); but it has its own power supply and > so isn't actually powered via USB. It gets woken up via USB when I > try to access it. That's a consequence of idleness, though, not a property of unmounting as such. It'd spin up if you ran a partitioner on it, for instance. -- http://www.greenend.org.uk/rjk/
From: Theo Markettos on 7 Jun 2010 07:31 Andy Botterill <andy(a)plymouth2.demon.co.uk> wrote: > I mean the disc spun down. There appears to be a windows utility to do > that. I do see a few websites which describe regular unix ways to do this. It really depends. I'm a bit out of date, but when I last looked many USB to PATA (and it was PATA then) bridge chips didn't support converting the SCSI 'unload' commands they receive via USB into ATA spindown commands. That means you can't set spindown for those enclosures. (SATA is the same as PATA protocol-wise, just with a different physical layer) The USB drive appears as a SCSI device, so the normal ATA control program hdparm doesn't work. I assume there is an equivalent SCSI spindown program, which might have a chance of being accepted by the enclosure, but I haven't tried it. It's such a simple change that I wouldn't be surprised if the bridge chips now supported this command conversion - anyone know? The other solution to this is eSATA - there's no protocol conversion so you can send whatever commands you like to the drive directly. Theo
From: Theo Markettos on 7 Jun 2010 07:33 Richard Kettlewell <rjk(a)greenend.org.uk> wrote: > I do backups to external drives too; however rather than monitoring > timestamps to construct incrementals, I used rsync with the --link-dest > option, so my backups are complete filesystem snapshots, with unchanged > files connected as hard links. There's a tool 'rsnapshot' which calls rsync to do this in a slightly more user-friendly way. Theo
From: Gavin Kinsey on 7 Jun 2010 13:59 Theo Markettos wrote: > > The USB drive appears as a SCSI device, so the normal ATA control program > hdparm doesn't work. I assume there is an equivalent SCSI spindown > program, which might have a chance of being accepted by the enclosure, but > I haven't tried it. "sg_start --stop" is the most reliable I've found for USB connected drives, it's worked on the half-dozen or so I've tried. It's in the sg3-utils package in Debian.
From: Nix on 8 Jun 2010 12:40
On 6 Jun 2010, Gordon Henderson said: > Actually, that's very intersting - I've been using noatime for a long > time on archive partitions/drives, but what would be nice to know is > what programs actually depends on it - for a file server where you're > not using dump, nor running programs that might want to know if a file > has been updates (email clients, mutt?) then it's really not needed... mutt and elm are the only programs I know of that care, and they can both do fine with the restricted semantics provided by relatime (that's why those semantics were defined, 'the minimal set that does not break mutt' :) ) |