On 2015-05-19 10:43 AM, Dimitri Maziuk wrote: > On 05/19/2015 11:42 AM, Bryn Hughes wrote: > ... >> recent LTO versions (5/6) you really need to make sure your disk setup >> on your backup storage server is capable of keeping up with the tape >> drive - most consumer hard drives top out at about 120MB/sec for >> sequential reads and much less than that for random I/O (such as having >> backup jobs writing to the disk at the same time as the tape drive is >> reading from it) > Wow these seagate nas drives must be magic then: it's 120MB/s sequential > read yet I get consistent 340MB/s sustained writes > >> 11-May 23:00 starfish-sd JobId 13: Despooling elapsed time = 00:02:24, >> Transfer rate = 345.8 M Bytes/second > ... >> 12-May 12:30 starfish-sd JobId 13: Despooling elapsed time = 00:02:25, >> Transfer rate = 343.4 M Bytes/second > ... >> 14-May 03:33 starfish-sd JobId 34: Despooling elapsed time = 00:02:27, >> Transfer rate = 338.8 M Bytes/second > ... >> 18-May 19:49 starfish-sd JobId 57: Despooling elapsed time = 00:02:26, >> Transfer rate = 341.1 M Bytes/second > and so on. On software raid-5-ish (raidz1) with lz4 compression at > filesystem level.
You realize that using a RAIDZ with LZ4 compression is going to give far better sequential performance than a single stand alone drive would with uncompressed data, right? ZFS RAIDZ volumes are perfect for sequential read/writes though they are still IOP limited. There's no magic. You have an appropriate configuration for what you're doing, exactly what I was intending to convey to the individual looking to build a brand new backup system. Try running straight EXT4 on a single drive with jobs spooling to the drive while it tries to feed an LTO5 drive and let's see if you can sustain anywhere close to 100MB/sec. Hint: you can't. My Bacula SD box has 5 old WD 'green' 1.5TB drives (5400 RPM) in a RAIDZ1 setup. Works great. > > How about you iostat that LTO 5/6 drive while a restore job is reading > from it and a backup job is writing at the same time and then post speed > comparisons? > You can't run both a restore and a backup to a tape device at the same time. Tape doesn't work like that. Bryn ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
