Re: unable to complete huge backup

Udo Rader <[email protected]> wrote:


> I just wanted to report back a bit ... 
>
> star is working now as expected. The problems I had gave me an
> opportunity to once more try two other tar tools around ???(bsdtar, pax).
>
> Both of the tools took a significant longer time to perform the 120GB
> backup:
>
> bsdtar took almost 11 hours
> pax took almost 10 hours
> and star finally takes about 8 hours
>
> so yes, star is indeed the fastest tar implementation around :-)

Thank you for this report.

BTW: which 'pax' are you talking off?


> Having very limited experience with tape drives, I would however really
> like to get some more feedback on how to speed up the process even more.
>
> So far I have learned that tuning can happen at 3 places:
>
> * the block size
> * the fifo size
> * bios settings on the tape controller
>
> any good pointers on how to set these things?

There are some hints in the man page, is this not sufficient?


> My current invocation looks like this:
>
> /opt/schily/bin/star \
> ???  errctl="WARN|GROW|SHRINK|OPEN|READ|READLINK|MISSLINK *" \
>   b=4096 \
>   -fifostats \
>   fs=32m \
>   -c \
>   -acl artype=exustar \
>   -f /dev/st0 \
>   ${BACKUPDIR} >>${LOGFILE} 2>&1

It is always better to use -dump (for exustar with extensions always on).

I prefer bs=xx before b= and if your drive/DMA/driver supports 2M, it is OK.
Note that most tape drives cannot write blocks bigger than the internal RAM 
size. Also note that you should check whether the drive is in variable block
size mode by reading the tape back with a bigger block size. Star should write
blocksize xxx with the first read. If this does not happen, you are in the less
optimal fixed block mode.

Jörg

-- 
 EMail:[email protected] (home) Jörg Schilling D-13353 Berlin
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