Kevin D. Alford wrote:
This is the output from a backup report for the 8MM drive after adding
the other filesystem.
STATISTICS:
Total Full Daily
-------- -------- --------
Estimate Time (hrs:min) 0:30
Run Time (hrs:min) 6:24
Dump Time (hrs:min) 5:52 5:47 0:06
Output Size (meg) 16422.0 16295.0 127.0
Original Size (meg) 40076.8 39376.1 700.7
Avg Compressed Size (%) 41.0 41.4 18.1 (level:#disks
Filesystems Dumped 14 10 4 (1:2 3:2)
Avg Dump Rate (k/s) 795.7 802.3 388.2
Tape Time (hrs:min) 5:33 5:31 0:01
Tape Size (meg) 16422.4 16295.3 127.1
Tape Used (%) 93.1 92.4 0.7 (level:#disks
Filesystems Taped 14 10 4 (1:2 3:2)
Avg Tp Write Rate (k/s) 842.9 839.3 1912.1
What is striking here is that the tape write rate for full dumps
is much slower than the incremental dumps. Normally this is
the other way around: it takes a few megabytes before the start
and stop time become small compared to the run time.
Also that rate (839 KB/s) is almost the same as the dump rate
for those full dumps (802 KB/s).
This is usually a sign of bypassing the holdingdisk (because it
is too small, or because of some other config parameters).
If this really is happening (I could be more sure if you did not
leave out the details of each DLE), then I'm not surprised:
if the tape cannot run in streaming mode, then the tape has to
stop/rewind-a-little/restart and this slows down the process immensly.
A faster tapedrive is hurt more by such behaviour, so that fits
this theory.
Now, if we can find some evidence that the holdingdisk is indeed
not used...
--
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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