Martin Simmons wrote: >>>>>> On Wed, 06 Sep 2006 16:48:18 -0400, Ryan Novosielski said: >> I have a question about my DDS4 drive... >> >> I have been backing up a 20GB FS with a DDS4 drive for quite some time. >> The filesystem has been getting increasingly full, and until recently >> was only 75% or so. I've reached 95% and my backup now exceeds one tape. >> The estimated backup size is 19.766GB. >> >> However, my DDS4 drive is reporting tapes full at roughly 17.8GB. >> Hardware compression is presumably enabled (I'm writing to /dev/rmt/1cbn >> on a Solaris box). I'd like to check somehow, but am not sure how to do so. > > Maybe the 'mt status' shell command will print it? You need to unmount the > drive from Bacula first.
I downloaded 'mtx' and ran tapeinfo. Compression is apparently enabled. However, any run says no tape is in the drive even if one is. >> I know a lot of the data is uncompressable, but wouldn't that make the >> data larger (ie. the data will hit the capacity of the drive and request >> a new tape), not make less fit on a tape? > > If the data is larger, then less fits on a tape :-) > > Remember that "larger" here means that the crappy expanding DDS4 compression > has caused more bits to be written to the tape than were written to the drive > by Bacula. Hence Bacula writes 17.8GB, which expands to more than 20GB (the > tape capacity) on the tape. Ah, this may be the key here. I will try using no compression -- I would expect to see 20GB or thereabouts fit on a tape afterwards. I have to make sure that it is actually writing uncompressed though. >> Any hints for what to try here? I am formatting the tape now to make >> sure that the capacity is correct (though this idea may be a holdover >> from when I was using DLT's, which seemed to be forward and backward >> compatible). >> >> If I am formatting /dev/rmt/1 instead of 1cbn, does that somehow turn >> off compression? > > You probably want to use /dev/rmt/1bn to get the other flags correct. > See man st. OK, I'm re-running my backup now with 1bn after doing some other testing to try to get to the bottom of this. It appears that a fill test only writes about 17GB too... I don't know what kind of data a 'bfill' does. -- ---- _ _ _ _ ___ _ _ _ |Y#| | | |\/| | \ |\ | | |Ryan Novosielski - Systems Programmer III |$&| |__| | | |__/ | \| _| |[EMAIL PROTECTED] - 973/972.0922 (2-0922) \__/ Univ. of Med. and Dent.|IST/AST - NJMS Medical Science Bldg - C630 ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
