On Tue, Aug 23, 2011 at 12:05 AM, Jérôme Poulin <jeromepoulin@xxxxxxxxx> wrote:
> On Mon, Aug 22, 2011 at 11:58 PM, NeilBrown <neilb@xxxxxxx> wrote:
>> So you have 8 MD RAID1s each with one missing device and the other device is
>> the next RAID1 down in the stack, except that last RAID1 where the one device
>> is a real device.
>
More tests revealed nothing very consistent... however, there is a
consistent performance degradation on our backups when using multiple
RAID devices, backup is every 2 hours and it is really slower.
Here are the results of bonnie++ which only show degradation of per
char even if I know it is not really significant.
Rewrite was going down more and more until it went back up for no
reason, really weird unexplainable results.
First line is from raw device, sdb2, then from md device, then
incrementally more md devices in series.
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
GANAS0202 300M 5547 93 76052 54 26862 34 5948 99 80050 49 175.6 2
GANAS0202 300M 5455 92 72428 52 26787 35 5847 97 75833 49 166.3 2
GANAS0202 300M 5401 91 71860 52 27100 35 5820 97 79219 53 156.2 2
GANAS0202 300M 5315 90 71488 51 22472 30 5673 94 73707 51 162.5 2
GANAS0202 300M 5159 87 67984 50 22860 31 5642 94 78829 54 138.6 2
GANAS0202 300M 5033 85 67091 48 22189 30 5458 91 76586 55 149.3 2
GANAS0202 300M 4904 83 65626 47 24602 34 5425 91 72349 52 112.9 2
GANAS0202 300M 4854 82 66664 48 24937 35 5120 85 75008 56 149.1 2
GANAS0202 300M 4732 80 66429 48 25646 37 5296 88 75137 57 145.7 2
GANAS0202 300M 4246 71 69589 51 25112 36 5031 84 78260 61 136.2 2
GANAS0202 300M 4253 72 70190 52 27121 40 5194 87 77648 61 107.5 2
GANAS0202 300M 4112 69 76360 55 23852 35 4827 81 74005 59 118.9 2
GANAS0202 300M 3987 67 62689 47 22475 33 4971 83 74315 61 97.6 2
GANAS0202 300M 3912 66 69769 51 22221 33 4979 83 74631 62 114.9 2
GANAS0202 300M 3602 61 52773 38 25944 40 4953 83 77794 65 125.4 2
GANAS0202 300M 3580 60 58728 43 22855 35 4680 79 74244 64 155.2 3
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
