Artem Kuchin wrote: > Hmm. what kind of HDD, RAID or whatever are you using? > My raid pretty much sucks. It is build it on the intel motherboard > LSI Megaraid. But i still get 81Mb/sec when doing > dd if=/dev/ar0 of=/dev/null bs=1M > > How much do you get on this?
geom_mirror on 2 desktop SATA drives, but the results of dd are pretty low: # dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 17.817686 secs (58850290 bytes/sec) As you can see, results with a single drive are better: # dd if=/dev/ad4 of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 16.219518 secs (64649023 bytes/sec) The mirror algorithm is "split": # gmirror list Geom name: data State: COMPLETE Components: 2 Balance: split Slice: 16384 Flags: NONE GenID: 0 SyncID: 1 ID: 1455065622 Providers: 1. Name: mirror/data Mediasize: 249999999488 (233G) Sectorsize: 512 Mode: r7w7e8 Consumers: 1. Name: ad4 Mediasize: 250000000000 (233G) Sectorsize: 512 Mode: r1w1e1 State: ACTIVE Priority: 0 Flags: DIRTY GenID: 0 SyncID: 1 ID: 2273811345 2. Name: ad6 Mediasize: 250000000000 (233G) Sectorsize: 512 Mode: r1w1e1 State: ACTIVE Priority: 0 Flags: DIRTY GenID: 0 SyncID: 1 ID: 926967552 Setting the algorithm back to "load" gives the performance similar to that of a single drive: # dd if=/dev/mirror/data of=/dev/null bs=1m count=1000 1000+0 records in 1000+0 records out 1048576000 bytes transferred in 16.551914 secs (63350740 bytes/sec) It's really unusual that geom_mirror cannot benefit from splitting requests.
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