rwk AT americom DOT com wrote:
Has anyone else experienced long estimates using amanda and hfstar on OS X?
Is there any way to improve the speed on this?
Why is it so slow when "dump" and "samba" are not?
The way tar works is inherently slower then dump (or samba).
Tar needs to "stat" each file it will backup. If there are many
small files, and/or lots of directories, it can take a long time.
During the estimate phase, tar is run with the option "--file /dev/null"
and gnutar is optimised to not even try to read the files; it only
collects the statistics if needed. I don't know if hfstar on OS X does
the same.
Dump bypasses the filesystem and reads the disk device, and as such
can very quickly get an estimate; it does no "stat" on each file.
Smbclient uses the builtin "du" command to get an estimate (only
an estimate; exclude files are not processed).
If it is really painfully slow, and I remember someone (Gerard?)
one wrote a very fast "estimate" for his particular case (no
subdirectories, only complete disks, no exclude file processing etc).
I don't know what happened with the code...
P.S. At first I thought it didn't work at all, but I increased the
value of etimeout to 60 minutes and it then worked.
You're still lucky, I once had a system where the estimate phase
took 2 hours 40 minutes! (Sun Solaris 2.6 with 18 Gbyte filesystem
with lots of small files. I moved the filesystem to a Linux box with
reiserfs and now the estimate phase takes only 18 minutes; to be honest
the content changed also a bit.)
--
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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