On 2 May 2006 at 8:55, Mark R Thomas wrote: > Hi everyone, > > I've been running Bacula version 1.38.2 on a 6.0-STABLE FreeBSD system > with a Postgres (v7.4) backend for several months. The machine hosting > the director is connected to an Exabyte 221L tape library (via SCSI) > with an IBM LTO-2 drive, but we currently only have LTO-1 tapes. > > With this setup (specifically, the LTO-1 tapes) I should be able to > store _at most_ 200GB of data per tape (100GB of storage times the > mythical 2x compression claimed by the hardware). Bacula reports, > however, that I am storing anywhere from 300 to 480 GB per tape. That > is, when I add up the nightly reports of how many sd bytes are written > before a tape gets changed out, or when I run "list volumes" from > bconsole and look at the "volbytes" column, both show well over the > expected 200GB of data being stored on a fresh tape. I have been > watching this for several months now and have noted this behavior > occuring on at least fifteen separate tapes.
Actually, if your files are quite compressible, you might even see a 10 GB file taking up only 1GB of space. > As far as scheduling goes, I do full backups every weekend and > incrementals inbetween and I am spooling 100GB to disk before writing to > tape. > > btape works famously and reports no problems (though I could never get > it to test tape spanning correctly, but I believe this problem is noted > in the documentation). I get tape spanning working correctly: http://www.freebsddiary.org/digital-tl891.php That's FreeBSD 6.something. > I have read and re-read the tape documentation > and have configured my tape drive according to the suggested FreeBSD > parameters: > For the tape drive itself: > > mt -f /dev/nsa0 seteotmodel 2 > mt -f /dev/nsa0 blocksize 0 > mt -f /dev/nsa0 comp enable I do none of that.... > > For the bacula-sd: > Hardware End of Medium = no > BSF at EOM = yes > Backward Space Record = no > Backward Space File = no > Fast Forward Space File = no > TWO EOF = yes > > Doing simple restores of small amounts of data has proven successful, > but I have yet to try a restore that would span an entire tape. You must. Get the two tape btape test working. > This worries me because it seems to me that this means either (1) data > is getting overwritten on each tape, (2) I have an enchanted tape > library or (3) Bacula is ruthlessly efficient and has, once again, > outsmarted me in it's backup strategies. It could still be very compressible data. But you must know for sure. Test. -- Dan Langille : Software Developer looking for work my resume: http://www.freebsddiary.org/dan_langille.php ------------------------------------------------------- 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
