incremental backups
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From: Andy Botterill on 5 Jun 2010 05:18 I'm writing some scripts to do full and incremental backups for my computer. My incremental (daily) backup works. However yesterday the daily backup was 44GB ( I would say 1.4GB is normal but high ). Looking at the find instruction I have used -mtime -ctime and -atime. http://www.brandonhutchinson.com/ctime_atime_mtime.html The above article implies that I don't really need to monitor -atime. Is this a safe/sensible thing to do? 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)? Thanks Andy.
From: Richard Kettlewell on 5 Jun 2010 05:28 Andy Botterill <andy(a)plymouth2.demon.co.uk> writes: > I'm writing some scripts to do full and incremental backups for my > computer. My incremental (daily) backup works. However yesterday the > daily backup was 44GB ( I would say 1.4GB is normal but high ). > > Looking at the find instruction I have used -mtime -ctime and -atime. > http://www.brandonhutchinson.com/ctime_atime_mtime.html > The above article implies that I don't really need to monitor -atime. > Is this a safe/sensible thing to do? atime is the time of the last read; you don't need to make a new backup just because atime has changed. Personally I often disable atime completely. > 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. 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. -- http://www.greenend.org.uk/rjk/
From: unruh on 5 Jun 2010 10:57 On 2010-06-05, Andy Botterill <andy(a)plymouth2.demon.co.uk> wrote: > I'm writing some scripts to do full and incremental backups for my > computer. My incremental (daily) backup works. However yesterday the > daily backup was 44GB ( I would say 1.4GB is normal but high ). Use rsync or rsnapshot to do your backing up. > > Looking at the find instruction I have used -mtime -ctime and -atime. > http://www.brandonhutchinson.com/ctime_atime_mtime.html > The above article implies that I don't really need to monitor -atime. > Is this a safe/sensible thing to do? > > 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)? No, almost certainly not. USB power is continuous ( you can plug in a flashlight). > > Thanks Andy.
From: Dave Liquorice on 5 Jun 2010 15:54 On Sat, 05 Jun 2010 14:57:35 GMT, unruh wrote: >> Does unmounting effectively disable the usb disk (err powering it >> down)? > > No, almost certainly not. USB power is continuous ( you can plug in a > flashlight). True enough, the OP needs to define what he means by "powering it down". Does he mean just the disc spun down or all the electronics off as well. The former might happen automagically or might be a config option in the particular USB drive or not at all. -- Cheers Dave.
From: Bernard Peek on 5 Jun 2010 16:23
On 05/06/10 20:54, Dave Liquorice wrote: > On Sat, 05 Jun 2010 14:57:35 GMT, unruh wrote: > >>> Does unmounting effectively disable the usb disk (err powering it >>> down)? >> >> No, almost certainly not. USB power is continuous ( you can plug in a >> flashlight). > > True enough, the OP needs to define what he means by "powering it > down". Does he mean just the disc spun down or all the electronics > off as well. > The former might happen automagically or might be a config option in > the particular USB drive or not at all. It would be really useful to be able to switch a USB port's power off under software control. -- Bernard Peek bap(a)shrdlu.com |