On Tue, May 23, 2006 at 10:39:09AM -0400, Paul Lussier wrote:
> On 5/23/06, Andreas Hallmann <hallmann AT ahatec DOT de> wrote:
> 
> >Since in the raid blocks are spreed sequentially (w.r.t the file) among
> >most (raid5) of the avail platters, it will behave more like a single
> >spindle with more layers.
> >
> >> So, my question is this: Am I doing the right thing by dumping these
> >> DLEs serially, or can I dump them in parallel?
> >
> >Dumping this DLEs sequentially is your only option to keep spindle
> >movements low. So your doing it the way I would do it.
> >Anything else should reduce your throughput.
> 
> 
> I'm looking for ways to speed up my daily incremental backups.  We may well
> be purchasing a new RAID array in the near future.  Which may allow me to
> migrate the existing data to it and split it up into multiple file systems,
> then go back and re-format the old one.

This is something you could easily try in stages.  For example,
suppose you have 8 DLEs defined on that raid, all as spindle "1".
Redefine 2-4 of them as spindle "2".  Also make sure your client
is not dumper limited.  If you see significant improvement,
define a few more DLEs as spindle "3" etc.

Recently I had a look at amplot results for my new vtape setup.
One thing it showed was that for 2/3 of the time, only one of the
default four dumpers was active.  I changed the default number of
dumpers to six and changed the number of simultaneous dumps per
client from one to two.  My total backup time dropped from over
four hours to one and a half hours.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
 4455 Province Line Road        (609) 252-0159
 Princeton, NJ  08540-4322      (609) 683-7220 (fax)