John Drescher wrote: > I made a try with this results >> >> JobId 7: Spooling data ... >> JobId 7: Job write elapsed time = 00:13:07, Transfer rate = 1.295 M >> Bytes/second >> JobId 7: Committing spooled data to Volume "FullVolume-0004". Despooling >> 1,021,072,888 bytes ... >> JobId 7: Despooling elapsed time = 00:02:19, Transfer rate = 7.345 M >> Bytes/second >> JobId 7: Sending spooled attrs to the Director. Despooling 6,816,214 bytes >> ... >> >> There is only a little improvement of performances.
Spooling or not spooling is very much a case of "it depends". There is little point in using spooling if the destination device is a disk drive and you are not using concurrent jobs.(*) For a NFS mounted destination network delays are your biggest problem. Make sure rsize and wsize are the maximum possible (32768 bytes on NFSv3, several Mb on NFSv4) If you have 1Gb/s ethernet, use jumbo frames. 7-8Mb/s is about right for untuned NFS on a 100Mb/s network environment. Because of NFS overheads you won't go much faster even though the network theoretical maximum is 12.5Mb/s (*) If you are using concurrent jobs and writing output to disk, spooling will usually help maintain speeds, because writing multiple files to the target disk will result in slowdowns due to head seeking. A single job despooling is more akin to streaming throughput. >> So I'm asking you what is the transfer rate in your jobs? These rates are >> normal or are they slow compared to yours? >> > > I use gigabit and LTO2 so I am seeing 20 to 50 MB/s per tape drive in > my 2 drive LTO2 autochanger. Spooling is almost always worthwhile if the target is tape. Spooling for differential/incremental jobs won't make much difference to the overall job rate but it WILL stop the tape drive "shoeshining" as it tries to write small amounts of data. That saves a lot of wear-and-tear. Spooling for full jobs is a win as long as your spool disks are fast enough to keep up with the tape drive (or at least, faster than what's coming off the backup filesystem). Spooling is _essential_ if you're running concurrent jobs, otherwise the jobs get interleaved on tape and restores will run incredibly slowly because the drive has to seek back and forth to get data in 64kB chunks. Concurrent jobs slow down the effective read rate when despooling to tape due to head seeking penalties. A single 7200rpm 320Gb HDD can _just_ despool fast enough to LTO2 to keep its buffers full whilst having another job simultaneously spooling data. A single 7200rpm 320Gb drive _cannot_ despool fast enough to LTO3 (or higher levels), even when despooling is the only activity on the disk. A 4 disk 7200rpm RAID0 stripe can just keep up with LTO4 whilst spooling another job. I use a set of Intel X25E SSDs in RAID-0 layout for the spool area. They are slightly faster in streaming output than 7200rpm drives, but the head seek penalty reduces from avg ~8ms down to under 0.1ms. I can concurrently despool to 3 LTO5 drives whilst spooling 3 more jobs. ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
