> I have an existing raid10,f2 array with four drives, all running on a single
> SATA controller. I have a second controller to add to the system and I'd like
> to split the existing drives between the two controllers. I'm hoping to make
> the configuration more robust against the possibility of a single controller
> failure. It would also be nice to get more performance out of the array, though
> I doubt having a single controller is a bottleneck with only 4 7200RPM drives.
>
> So with four drives sda, sdb, sdc, and sdd and two controllers C1 and C2, should
> I go with
>
> C1: sda, sdb
> C2: sdc, sdd
>
> or
>
> C1: sda, sdc
> C2: sdb, sdd
>
> or some other configuration?
>
> I've looked through the last six months of messages in the archives, and the
> md(4) and mdadm(8) manpages, and the wiki on
https://raid.wiki.kernel.org/ and
> didn't see anything that quite answers this question at a level I can
> understand. If there is a reference I can consult, I'm happy to keep digging.
>
> If it will help, the output of /proc/mdstat and "mdadm --detail" on the md
> device are included below.
>
>
> Mike McCallister
>
>
> # cat /proc/mdstat
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4]
> [raid10]
> md3 : active raid10 sda5[0] sdd5[3] sdc5[2] sdb5[1]
> 1445318656 blocks super 1.1 256K chunks 2 far-copies [4/4] [UUUU]
> bitmap: 6/345 pages [24KB], 2048KB chunk
>
> # mdadm --detail /dev/md3
> /dev/md3:
> Version : 01.01.03
> Creation Time : Sun Nov 9 22:47:00 2008
> Raid Level : raid10
> Array Size : 1445318656 (1378.36 GiB 1480.01 GB)
> Used Dev Size : 1445318656 (689.18 GiB 740.00 GB)
> Raid Devices : 4
> Total Devices : 4
> Preferred Minor : 3
> Persistence : Superblock is persistent
>
> Intent Bitmap : Internal
>
> Update Time : Sun Apr 11 11:47:09 2010
> State : active
> Active Devices : 4
> Working Devices : 4
> Failed Devices : 0
> Spare Devices : 0
>
> Layout : near=1, far=2
> Chunk Size : 256K
>
> Name : ozark:3
> UUID : e7705941:e81cfbe1:7bf6ab9f:2b979a89
> Events : 84
>
> Number Major Minor RaidDevice State
> 0 8 5 0 active sync /dev/sda5
> 1 8 21 1 active sync /dev/sdb5
> 2 8 37 2 active sync /dev/sdc5
> 3 8 53 3 active sync /dev/sdd5
>
>
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