Richard Elling wrote: > Dana H. Myers wrote: > >> Jonathan Wheeler wrote: >> <snip>
>>> On the one hand, that's greater then 1 disk's worth, so I'm getting >>> striping performance out of a mirror GO ZFS. On the other, if I can get >>> striping performance from mirrored reads, why is it only 94MB/sec? >>> Seemingly it's not cpu bound. >> >> >> >> I expect a mirror to perform about the same as a single disk for writes, and >> about >> the same as two disks for reads, which seems to be the case here. Someone >> from >> the ZFS team can correct me, but I tend to believe that reads from a mirror >> are >> scheduled in pairs; it doesn't help the read performance to have 6 more >> copies of >> the same data available. Makes sense, thanks Dana. > Is this an 8-way mirror, or a 4x2 RAID-1+0? For the former, I agree with > Dana. Yup, a full 8 way mirror. > For the latter, you should get more available space and better performance. > 8-way mirror: > zpool create blah mirror c1d0 c1d1 c1d2 c1d3 c1d4 c1d5 c1d6 c1d7 > 4x2-way mirror: > zpool create blag mirror c1d0 c1d1 mirror c1d2 c1d3 mirror c1d4 c1d5 > mirror c1d6 c1d7 > I agree, the it would be a win both ways. Though in my own defence I never intended to run a full 8 way mirror for actual use - it was just a fun test to see what would happen, or that the results might help point towards a bottleneck that wasn't so obvious with the other raid levels. Thanks, Jonathan Wheeler This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
