On Thu, May 23, 2013 at 01:59:33PM +0000, McGraw, Robert P wrote:
> Amanda Server Info:
>
> Thu May 23 05:36:00 2013: amandad: build: VERSION="Amanda-3.2.3"
> Thu May 23 05:36:00 2013: amandad: BUILT_DATE="Tue Feb 5 17:10:59
> EST 2013" BUILT_MACH=""
> Thu May 23 05:36:00 2013: amandad: BUILT_REV="3994"
> BUILT_BRANCH="3_2_3"
> Thu May 23 05:36:00 2013: amandad:
> CC="/opt/SunStudio/sunstudio12.1/bin/cc"
>
> Amanda.conf snippet:
>
> define changer "sl24" {
> tpchanger "chg-robot:/dev/changer/0"
> changerfile "chg-zd-mtx-state"
> property "tape-device" "0=tape:/dev/rmt/0cbn"
> property "eject-before-unload" "true"
> property "eject-delay" "10"
> property "unload-delay" "10"
> property "use-slots" "1-20"
> property "load-poll" "0s poll 5s until 120s"
> device-property "BLOCK_SIZE" "2 mbytes"
> device-property "LEOM" "true"
>
> define tapetype LTO4-HWC {
> comment "LTO4-Hardware Compression on."
> length 1500 gbytes
> filemark 0 kbytes
> speed 102216 kps
> part_size 40GB
> }
>
> holdingdisk hd1 {
> comment "holding disk"
> directory "/zexport/planck/holdingdisk/daily"
> use 3000GB
> chunksize 10GB
> }
>
>
> I use hardware compression to max the size of the tape. Uncompressed the tape
> is 800GB compressed the theoretical max size is 1.6TB. I know that I will not
> get the 1.6TB.
>
> In the amanda.conf file I tell amanda that my tape is "length 1500 gbytes"
> and that my tape drive uses LEOM.
>
> Why does amanda stop at %52 when I still have 1.5TB of data in the holding
> disk to write to the tape? It is hard to believe that the LTO4 compression is
> so bad that I am not getting any compression at all.
Perhaps this is a case of misunderstanding the tape properties.
Your tapes will only hold 800GB of data! Period.
However, if your data is compressible (lots of data is not)
then the hardware compressor might fit more data into those
800GB of space on the tape. If your data is not compressible
then the hardware compressor can't work magic and squeeze
more onto the tape.
Lots of data is not compressible, or can be compressed only
a small amount. For example, already compressed data, audio,
photo, and video, compiled programs, encrypted data, and
(I think) database files compress poorly.
Jon
--
Jon H. LaBadie j...@jgcomp.com
11226 South Shore Rd. (703) 787-0688 (H)
Reston, VA 20190 (609) 477-8330 (C)
