On 14/01/16 09:29, Adam Goryachev wrote: > On 14/01/16 08:14, Gandalf Corvotempesta wrote: > >> raw performance writing to disk on BPC server (same partitions used by >> BPC as storage): >> >> # dd if=/dev/zero of=/var/backups/test.img bs=1M count=10000 >> ^C8815+0 records in >> 8815+0 records out >> 9243197440 bytes (9.2 GB) copied, 142.267 s, 65.0 MB/s > Totally irrelevant. BackupPC is doing lots of small random reads and > writes. However, maybe that is relevant, because 65MB/s on any single > HDD from the past 5 years, let alone a RAID array is abysmal for > streaming writes. Even a single drive should be capable of at least > 100MB/s. > > Here is the same statistic from one of my BPC v3 servers: > dr:/mnt/imagestore# dd if=/dev/zero of=/var/backups/test.img bs=1M > count=10000 > 10000+0 records in > 10000+0 records out > 10485760000 bytes (10 GB) copied, 16.135 s, 650 MB/s > Whoops, that was writing to the SSD for the root FS.... I was rather surprised at the high number, but didn't stop and think properly. Please see the revised stat: dr:/mnt/imagestore# dd if=/dev/zero of=test.img bs=1M count=10000 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 81.5089 s, 129 MB/s
However, note that this is happening while BackupPC_nightly is running, so there is plenty of other IO happening in the background. (in v3 there is a nightly process which checks every file in the pool to see if it is still needed or not). > This is a LV sitting on a RAID5 array: > md0 : active raid5 sde1[4] sdc1[3] sdd1[2] sdb1[0] > 11720658432 blocks super 1.2 level 5, 512k chunk, algorithm 2 > [4/4] [UUUU] > > Which is using these drives: > Model Family: Western Digital Red (AF) > Device Model: WDC WD40EFRX-68WT0N0 > User Capacity: 4,000,787,030,016 bytes [4.00 TB] > Sector Sizes: 512 bytes logical, 4096 bytes physical > Rotation Rate: 5400 rpm > > I'm sure you said you had 7200rpm disks, so you should get even better > performance for both random r/w as well as streaming writes. Which > brings me back to my earlier concern that you are using a VM for > backuppc, it is sharing it's performance with other things, which > works very poorly when dealing with spinning disks (even a streaming > write like your example is mixed with other random I/O which means it > kills performance). > > Please diagnose and resolve the underlying performance issues, then > come back to BPC and see how it performs. > > Regards, > Adam > -- Adam Goryachev Website Managers www.websitemanagers.com.au ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
