Sandi S schrieb: > > > It seems that the job with spooling enabled can feed the drive at a > > higher speed, but in the the end both jobs had an average write speed > > of 75 MB/s (no spooling) and 77 MB/s (spooling) The compression ratio > > of this backup was ~1.45:1. The spool device is a large RAID5 which is > > able to do seq. reads at ~160 MB/s. BTW: with LTO-3 I was able to > > write to tape with the same speed. I'm not sure what the limiting > > factor is at the moment. Differnt blocksizes didn't change anything. > > > > LTO-4 needs a minimum of 40 MB/s to stream the data continuously to > > tape. I'm still not sure if the drive has to stop very often during > > backup, because there are some dropouts below 40 MB/s (even with > > spooling). On the other hand, the drive has a 128 MB buffer which > > should be able to cache these short dropouts. I'd like to avoid > > spooling because it nearly doubles the time needed for serveral TB. > > > > Therefore I'm still looking for a way to get the number of start/stops > > that a drive needs while writing to tape. > > > > Does anyone know a tool that is able to get this information from the > > drive - in case HP drives do store this information somewhere at all. > > I am also interested in this. > > I have pretty big full backup (3,2TB) for which I need around 12 LTO-2 tapes > (with hw compression on). I use spooling with max size of 215GB, and > typically spooling (of max size) lasts 2h50min, while despooling lasts > 2h40min. Is this normal that spooling lasts longer than actual writing to > the tapes? > > I would drop the spooling part, but I'm worried about tape shoe-shining. > (If only bacula can do despooling and start spooling the next chunk of the > same job at the same time.)
Yes, even a simple FIFO with couple of GB or less would be sufficient to avoid shoe-shining. Bacula's spooling has other advantages than only avoid shoe-shining, but in our case it's not the perfect solution. Ralf ------------------------------------------------------------------------- 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
