Hi Martin, >> 1. Even with brand new tapes, on two different tape drives, using >> continuous cleaning cycles, the tapes that used to store between 11.5 >> and 13 GB uncompressed data on a windows machine only take about 8 GB >> using bacula (same drive, same tapes). >> >> Following the advice to switch off software compression when hardware >> compression is enabled, we run tests with following results (always the >> same fileset of 23 GB uncompressed data) >> >> hw-compress sw-compress spool size data/tape total # of tapes used >> on on 14 GB 8.2 GB 1.7 >> on off 23 GB 12.9 GB 1.8 >> >> so we use the installation with both sw and hw compression turned on, as >> it gives us better performance and less tapes/backup. >> >> Why is it impossible to store more then 8 GB on a 12/24GB tape. Again: >> we ran the tests on multiple different drives (HP15xx and Sony >> DDS3-drives). > > The problem is that DDS hw compression is not very good. In particular, when > you use sw compression as well, the data written to tape actually gets > expanded by the hw compression so your 8.2 GB of input gets written as 12 GB > on the tape! > Have you tried with hw compression off and sw compression on? Yes we've tried. On the Sony drives there's a tool that reports compression as disabled, but there where no changes in tape capacity, though. According to the manual the drive switches are set to control compression via software and if we turn off compression on a windows box, it's enabled after pluggin the unit back into the Linux box. So far we haven't noticed any difference with compression reported ON or OFF.
>> 2. Up to now a verify at level "VolumeToCatalog" always (!) brings up at >> least one error of the type "Error: block.c:317 Volume data error at >> 3:2817! Block checksum mismatch in block=2817 len=64512: calc=8fe728a4 >> blk=bd217fe3" in the middle of the tape. >> After that bacula dupms the whole remaining file list into an email >> message of about 30MB in size. >> >> - Is there any way to make Bacula stop to send the file list while keep >> on sending email notifications ? > If your mailcommand uses bsmtp, then you can set the -l option. Thanks for the hint! That works for now, but it only limits the mail length and peculates the end of the error report. >> - How can it be, that a single error renders the whole tape of a backup >> useless ? Why does bacula not continue to verify the other 80% of a >> backup and tells something like "block error while reading ..., missing >> files ...." ? > Hmm, I thought it would continue. Are there any other errors after the > checksum mismatch? Can you try restarting the bacula-sd with the -p option? No, it stops and there aren't any more errors after that. I changed the bacula-ctl-sd script to call bacula-sd with -p and I'll see next week if it works. BTW we are testing bacula 2.0.3, if that makes any difference. Thanks again for your help an I'll keep you posted, Carsten ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
