Hi all, I've been using Bacula for a number of years but recently got hold of an old tape autochanger with an LTO-4 drive, which I would like to use to have Bacula write to tape instead of my previous disk/file config.
I think I have everything set up, all the tapes are labelled and Bacula switches tapes when each one fills up, however after the first tape started writing at 80MB/sec, the rest of them only write at 60-65MB/sec. Listening to the unit the drive stops, rewinds, then starts again quite a lot, so the drop in write speed appears to be due to shoe-shining. I have set up a spool file on my /tmp partition, which is a Linux tmpfs filesystem (data is stored in RAM), so there should be no speed issue reading or writing the spool file. Certainly Bacula writes to it at over 120MB/sec when the file daemon can deliver data fast enough, yet when despooling the shoe-shining occurs. The machine has no swap file (and 64GB RAM) so the data is definitely staying in memory the whole time. I am not sure why the system cannot basically write from memory to the tape at its full speed. The bacula-sd process only uses 30% of one CPU when writing, so it can't be an issue with CRC calculations (although I would've thought those would happen during spooling rather than despooling). In the manual there is some mention of setting the maximum block size to be larger to avoid shoe-shining, so I will try that when the current full backup has finished (probably another day or two at this rate) but I'm not sure why that would affect things either. Does anyone know why despooling 8GB of data from memory onto the tape drive would result in shoe-shining? Many thanks, Adam. _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
