You said it yourself: RAID. Not magic, it is only writing on multiple disks in parallel.
The disks I have in my NAS are WD Reds, rated at 112 MB/s and performance tested (by Tom's Hardware) to write at speeds from about 70 MB/s (center of the disk) to about 150 MB/s (outside). I've seen much higher speeds in my NAS, where they are configured in a 12 drive array with 2 parity disks. The NAS has two 1 GB network interfaces bonded together to 2 Gbit. That translates to roughly 250 MB/s, but the network is *still* more of a bottleneck than the disks. The disks only become the deciding factor when there's a lot of non-sequential access (many people using it at the same time, plus it's also doubling as the iSCSI store for a few less important VMWare virtual machines). -----Original Message----- From: Dimitri Maziuk [mailto:dmaz...@bmrb.wisc.edu] Sent: 19 May 2015 19:43 To: bacula-users@lists.sourceforge.net Subject: Re: [Bacula-users] Is Bacula and a LTO drive right for me? 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. 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? -- Dimitri Maziuk Programmer/sysadmin BioMagResBank, UW-Madison -- http://www.bmrb.wisc.edu ------------------------------------------------------------------------------ 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
