[CentOS] slow usb hard disk performance.

[Les Mikesell]

On Tue, 2005-12-06 at 10:44, Joshua Baker-LePain wrote:

> > Amanda uses dump or tar for the backups and adds one extra block
> > as a header to each backup.  You can strip off the header with
> > dd and restore with dump or tar alone.  It was a nice system
> > 15 years ago but hasn't had a lot of development since.  It
> > has one big flaw in that it can't split a single filesytem
> > backup across more than one tape even though it can do many
> > hosts/filesystems in one run splitting different backups within
> > the run over different tapes. With todays big disks that's probably
> > fatal.
> 
> I hardly consider it fatal.  I backup 5.5TB of space (4 FSs) to
> an AIT3 changer without a problem.  Also, tape spanning is included
> in the 2.5 branch, which is officially in beta now.

The really brilliant part of amanda is the way it schedules the
mix of full and incremental runs each night to fill a tape of
a given size.  This works nicely when you have a large number
of small filesystems (relative to the tape size) but falls down
badly when a single full nearly fills the tape because it will
start streaming some small runs that are finished first, then
the big one won't fit, and even during amflushes it doesn't
know enough to put the big run on the tape first so you end up
with the small ones that can be grouped in a later amflush. The
tape spanning change may help a lot with this.

-- 
  Les Mikesell
   lesmikesell at gmail.com