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Re: Prefere a dump from the disklist and do several dumpes to holding disk?
2006-09-11 11:16:46
On Mon, 11 Sep 2006 at 4:27pm, Dominik Schips wrote
1. How can I tell AMANDA to start with the big directories first and then the
small directories?
As I have seen AMANDA allways starts with the smallest and then the next
biggest and so on.
'man amanda.conf' and look for the 'dumporder' and 'taperalgo' flags.
2. I use a holding disk for the configuration. But AMANDA always do only one
dump at the same time.
How can I tell AMANDA to dump more directories at the same time to the holding
disk so that the LTO device can backup the data faster and don't have to wait
for the dumps of the holding disk?
I'm a bit confused about your setup. As I understand it, all the client
data is rsynced to one server, and you're backing up that server. But is
that server also the amanda server to which the tape drive is attached?
If that's the case, then a holding disk is a waste of time. You're not
adding any parallelism and you're adding the time it takes to copy the
data from one directory to another.
Tape Time (hrs:min) 3:35 3:35 0:00
Tape Size (meg) 374733.9 374733.9 0.0
Tape Used (%) 194.1 194.1 0.0
Filesystems Taped 12 12 0
Avg Tp Write Rate (k/s) 29707.6 29707.6 --
That tape write rate is too slow. Native speed for an LTO3 drive is
rated at ~80MB/s. It can throttle back to about half that without
shoe-shining, but any slower than that and you're putting unnecessary wear
and tear on your drive and your tapes as well as losing tape capacity.
USAGE BY TAPE:
Label Time Size % Nb
Daily027 1:59 224033.5 116.1 11
Daily028 1:36 150700.4 78.1 1
All that really should have fit on one tape. It probably didn't b/c of
the shoeshining mentioned above.
So, step 1 is to optimize your backup server. First, you probably want to
recompile amanda with the --with-maxtapeblocksize set to something larger
than amanda's default of 64KB. This lets you use the 'blocksize' keyword
in your tapetype -- I use 2048 KB for my LTO3 drive, and my tape write
speed averages about 60MB/s.
You also need to look at your server's disk I/O performance. Feeding a
tape drive at 60MB/s is non-trivial, especially if the disk is doing
*anything* else at the same time. Use tools like bonnie++ and tiobench to
benchmark your disks. If they can't sustain read speeds of at least
50MB/s, look at upgrading. My server for my LTO3 library has a hardware
RAID0 across 4 7200RPM SATA disks, and it can only keep up with the one
tape drive. I'm upgrading the server simply so that I can use both tape
drives in the library simultaneously.
Good luck.
--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University
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