My configuration:
zorn->[8] > amadmin
daily
version
build: VERSION="Amanda-2.5.2-20070530"
BUILT_DATE="Thu
May 31 09:14:26 EDT 2007"
BUILT_MACH="SunOS
zorn.math.purdue.edu 5.10 Generic_118833-03 sun4u sparc
SUNW,Sun-Fire-280R"
CC="/pkgs/gcc-3.4.3/bin/gcc"
CONFIGURE_COMMAND="'./configure' 'CC=/pkgs/gcc-3.4.3/bin/gcc'
'MT=/opt/csw/bin/mt' 'MTF=-f' 'MTX=/opt/csw/sbin/mtx' 'PERL=/opt/csw/bin/perl'
'--prefix=/local/Amanda/amanda-2.5.2-20070530' '--with-user=amanda'
'--with-group=operator' '--with-gnutar=/opt/csw/bin/gtar'
'--with-gnutar-listdir=/var/amanda/gnutar-lists'
'--with-includes=/opt/csw/include' '--with-libraries=/opt/csw/lib'
'--with-index-server=zorn' '--with-smbclient=/pkgs/samba/bin/smbclient'
'--with-tape-device=/dev/rmt/1bn' '--with-changer-device=/dev/changer/1'
'--with-maxtapeblocksize=2048'"
My tape unit is a Sun C4 38 slot and 1 LTO2 tape
drive. My tapetype is defined as followed
define tapetype LTO2-HWC {
comment
"LTO-2-Hardware Compression on."
blocksize 1024 kbytes
length 300000
mbytes #200G
filemark 0 kbytes
speed 27315
kps #27 Mb/s
}
“length 300000 mbytes” was calculated by
1.5 times the actual size of 200GB.
Up to now my dumptype has had compress equal to none.
I decided to let the hardware do the compression work. The problem with this is
the calculation of the length is just a guess and seems to cause problems when
trying to fit files on the tape. In some cases amanda thinks it has more tape
than it really does so it tries to write a bigger file to the last part of the
tape and fails.
I am thinking of changing my setup to do software
compression and see if this will give me better tape usage.
Q1) I have asked Sun and the makers of the LTO2 drive
and it seems there is no way to turn hardware compression on or off on this
unit, it is always on. From my reading in the Amanda forum it seems that the
LTO2 drive will sense if the data is compressed and turn off hardware
compression if the data is already compressed. Is this correct?
Q2) Any suggestions, pros or cons in going this
direction? I guess the trade off is that I would get better tape usage at the
expense of compute time to do the software compression.
Q3) From the config.log it seems the default program
for compression is gzip and it uses –fast or –best. From gzip man
page it says I can use -#x where x is between 1 (fast) 9 (best). Is there a way
to set the compress number without having to use the “compress server custom”?
Thanks
Robert
_____________________________________________________________________
Robert P. McGraw, Jr.
Manager, Computer System EMAIL:
rmcgraw AT purdue DOT edu
Purdue
University
ROOM: MATH-807
Department of Mathematics PHONE: (765)
494-6055
150 N. University Street FAX: (419)
821-0540
West Lafayette,
IN 47907-2067
