Joe Konecny wrote:
Paul Bijnens wrote:
Next, how large is the image itself. If the dump file is 30 Gbyte
then it still takes some time to crawl through that amount to locate
your 140K file. A tape device is a sequential device. Indexing
with amanda does not turn it into a random access device.
I'm aware that indexing doesn't make it a random access device.
I figured somehow it could speed up finding a file on tape though.
The netware server I'm replacing, (a very old pentium 133 with a DLT
tape drive and arcserve) could restore any file anywhere on tape in
less than a minute. I figured this new setup on FreeBSD/Amanda
would be faster.
Common misconcepton. Amanda actually only schedules and manages
the backup, but the backup itself is done by another program,
dump or gnutar or smbclient currently. You run into limitations
of the dump/restore programs (supplied by the OS).
Dump or restore does not have any intelligence build into
that can fast skip forward in a tape device (much too device
dependant probably).
The fast skip forward only works on a "file" on tape. Amanda
makes one tapefile for each backup image. A possibility
is to split up the one huge filesystem into smaller ones, where
fsf can skip over in less than a minute.
But from the statistics below, you can see the dump itself
took 1 hour 43 minutes. The restore was done in about one
hour and a half, about in the time I would have expected.
Actually, depending on where the file is located in the
complete backup image, you can have the file restored already
after a few minutes if you're lucky.
The restore program does not break off, after restoring
that one file, but reads the rest of the image, comparing
each file to the list to be restored. I never tried this
with restore, but using gnutar, I just hit ctrl-C when the
file is restored to the filesystem.
STATISTICS:
Total Full Daily
-------- -------- --------
Estimate Time (hrs:min) 0:02
Run Time (hrs:min) 2:43
Dump Time (hrs:min) 1:43 1:43 0:00
Output Size (meg) 12314.1 12314.1 0.0
Original Size (meg) 12314.1 12314.1 0.0
Avg Compressed Size (%) -- -- --
Filesystems Dumped 1 1 0
Avg Dump Rate (k/s) 2038.2 2038.2 --
Tape Time (hrs:min) 0:58 0:58 0:00
Tape Size (meg) 12314.1 12314.1 0.0
Tape Used (%) 34.3 34.3 0.0
Filesystems Taped 1 1 0
Avg Tp Write Rate (k/s) 3616.1 3616.1 --
USAGE BY TAPE:
Label Time Size % Nb
DailySet1001 0:58 12314.1 34.3 1
NOTES:
planner: Incremental of R4P17.gmihome.com:amrd0s1f bumped to level 2.
taper: tape DailySet1001 kb 12609664 fm 1 [OK]
DUMP SUMMARY:
DUMPER STATS TAPER STATS
HOSTNAME DISK L ORIG-KB OUT-KB COMP% MMM:SS KB/s MMM:SS KB/s
-------------------------- --------------------------------- ------------
R4P17.gmihom amrd0s1f 0 1260962012609620 -- 103:072038.2 58:073616.1
Tip: have a look a the "columnspec" directive in amanda.conf to avoid
this kind of unreadable output where columns run together without space
between them.
--
Paul Bijnens, Xplanation Tel +32 16 397.511
Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM Fax +32 16 397.512
http://www.xplanation.com/ email: Paul.Bijnens AT xplanation DOT com
***********************************************************************
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* stop, end, F3, ~., ^]c, +++ ATH, disconnect, halt, abort, hangup, *
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