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Re: [Networker] Long NDMP Backups
2008-02-26 16:12:48
Matthew Huff wrote:
The main advantage is that it runs in parallel rather than in serial. For
example, lets say your /vol/vol0 was 1TB, and had 10 qtrees each with 100MB in
it. You could increase the client parallelism in legato to 10, and when you
started the backup with a saveset of:
/vol/vol0/dir_a
/vol/vol0/dir_b
/vol/vol0/dir_c
/vol/vol0/dir_d
/vol/vol0/dir_e
/vol/vol0/dir_f
/vol/vol0/dir_g
/vol/vol0/dir_h
/vol/vol0/dir_i
/vol/vol0/dir_j
You would get 10 parallel backups each taking around 1/10 of what the volume backup would take. If you had the I/O and tape drive capacity, you would be reducing your backup time by 90%. Of course, that's an ideal situation.
I am quite sure that this is a great way of killing your filer. Our
3050 can push at LTO-3 (~70MB/s) speed while consuming many CPU cycles
(our CPU graphs are broken, so I cannot provide real numbers, but 20%
seems about right). Considering this, running too many NDMP backups at
once will make the filer unresponsive (assuming that it does any useful
work, this might be unacceptable). It would not even get things to work
any faster because if the filer is at 100% CPU utilization, it will
become your bottleneck (it could even get you worse performance, as you
will most likely have contention on your aggregate, volume or RAID group.
--
-- Yaron.
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