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Re: *Slow* amrestore
2004-03-11 14:23:47
Joshua Baker-LePain wrote:
I'm reading some somewhat large (14-18GB) images off of AIT3 tapes, and
it's taking *forever*. Some crude calculations show it coming off the
tape at around 80 KB/s, whereas it was written out at 11701.6 KB/s. The
tapes were written in variable block size mode. What's the best way to
read these images more quickly?
Are you piping the amrestore output, say to uncompress and extract
files? Maybe the extraction process is too slow, and causes the tape to
have to stop and reposition while the pipe is emptying out. I wonder if
you could put a bigger buffer in the pipe somehow, that might help, say
64 MB to begin--I remember seeing a cat-like program that could buffer a
pipe, I think it was with Linux software for doing backups to CD-R.
I would try "amrestore -c" to just dump the image off the tape, and then
do the uncompress and extraction separately, but you will need enough
disk space to do it. Worst case, you could try "amrestore -r" and use
"dd bs=32k skip=1 if=dump-file" to skip over the header, and then pipe
that to the uncompress and extract processes.
--jonathan
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