> On Tuesday 03 April 2007, Sebastian Henrich wrote: > >Hello, > > > >I'm using amanda 2.4.5 to backup my server. The tape is a HP DAT 72. > >This drives stores 36 GB of uncompressed data. I switched the > >hardware compression off and tried to use the software compression. > >Now I have the problem that amanda tells me every time > > > You may be getting bit by something I ran into several years ago now. > > If the tape is written with the hardware compression on, then the drive > will detect that and turn the compression on even if you think its turned > off. Then, when feeding it data that's already gzipped, the hardware > compressor is powerless to compress it further, and may expand it a few > percentage points with its attempts at compressing data that's already > been smunched with gzip. > > The usual cure works like this: > > rewind the tape > read the header block out to a file with dd > rewind the tape > turn the compression off again > output, using dd, enough data from /dev/zero to cause the drive to have to > flush its buffers, something in the 2 to 10 meg range should be enough, > the point being that you turn the compressor off and don't move the tape > until it has to flush its buffers. At that point, that hidden > compression flag will finally be turned off in the tape header. > rewind the tape again > Do an amtapetype -f /dev/ice -e 36GB, and copy the resulting size data > into your tapetype define in your amanda.conf. > rewind it again > dd the tapes label block back onto the tape. > > Do this for each tape that has been used with the compressor turned on, > skipping the amtapetype step after the first tape. And you will of > course lose the data on that tape, so its probably a good idea to do this > to each tape in the rotation in the hours before it will be re-used > again. > > rewind it again. > run amcheck to see if the label is indeed good, it should be.
I diabled the hardware compression before I used the tapes for the first time like it's described in the docs. mt shows me that hardware compression is off after inserting a tape. So I think that it's really disabled. > > gzip -best can compress some directories to less than 10% of their actual > size. > > Amanda also tracks the amount of compression on a per dle basis, so if you > know beforehand the ratio, you can put it in the dumptype spec section to > give amanda a head start on a good guess. How can I put the ratio in the dumptype spec? > > >INFO planner Incremental of server:/srv/samba/profile bumped to level 2. > >INFO planner server /home 20070404 0 [dumps too big, 15459005 KB, > >full dump delayed] > > > >Amanda is configured to do a full backup each time which is > >impossible at the moment. I tried to backup ~45 GB of well > >compressable data. Normally amanda should be able to store the files > >compressed on the tape. > > > >Has anybody some hints for me? > > > > Thanks > > > > Sebastian > -- "Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: http://www.gmx.net/de/go/topmail -- "Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: http://www.gmx.net/de/go/topmail
