Michael D Schleif wrote:
Since the tape drive change, I have wondered why I didn't seem to be
getting all the data on some tapes. Clearly, with Amanda, some days it
just doesn't want to send a full 12GB to tape; but, mostly, I have been
seeing <9GB going to tape, and balance sitting in holdingdisk.
Today, I did this:
# time sudo -u backup amtapetype -e 12g -f /dev/nst0 -o
Writing 32 Mbyte compresseable data: 37 sec
Writing 32 Mbyte uncompresseable data: 35 sec
I'm pretty sure that your hardware compression is indeed off.
Otherwise you would have a very large speed difference in writing
uncompressed or compressed data, that is tested here. It would
be twice or three times as fast, instead of only 2 seconds difference.
Estimated time to write 2 * 12288 Mbyte: 26880 sec = 7 h 28 min
wrote 298832 32Kb blocks in 76 files in 10632 seconds (short write)
wrote 310628 32Kb blocks in 158 files in 10840 seconds (short write)
These two lines are actually a little strange. I would have expected
that the second pass wrote a little bit less then the first pass (and
the difference is the space taken up by the additional filemarks).
But you seem to write more in the second pass. Even 400 Mbyte.
In previous version of amtapetype, this would be reported as a negative
filemark size of -4603 Mbyte (the granularity of measuring is 32K).
What actually happened is that in the first pass, there was a hard write
error, interpreted as an end-of-tape.
This is a symptom of an almost bad tape or tapedrive or dusty heads.
Some OS's report an excessive soft-error rate in the kernel messages.
Do you find anything like that in /var/log/messages?
define tapetype unknown-tapetype {
comment "just produced by tapetype prog (hardware compression off)"
I'm pretty sure that your hardware compression is indeed off.
Otherwise you would have a very large speed difference in writing
uncompressed or compressed data, that is tested here.
length 9522 mbytes
filemark 0 kbytes
speed 908 kps
}
real 364m39.451s
user 0m2.724s
sys 0m28.719s
What is going on here?
How can I get a full 12GB tape length?
What do you think?
--
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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