Re: Very slow LVM performance
Mike Bird put forth on 7/12/2010 4:00 PM:
> On Mon July 12 2010 12:45:57 Arcady Genkin wrote:
>> Creating the ten 3-way RAID1 triplets - for N in 0 through 9:
>> mdadm --create /dev/mdN -v --raid-devices=3 --level=raid10 \
>> --layout=n3 --metadata=0 --bitmap=internal --bitmap-chunk=2048 \
>> --chunk=1024 /dev/sdX /dev/sdY /dev/sdZ
>
> RAID 10 with three devices?
I had the same reaction Mike. Turns out mdadm actually performs RAID 1E with
3 disks when you specify RAID 10. I'm not sure what, if any, benefit RAID 1E
yields here--almost nobody uses it.
RAID 0 over (10 * RAID 1E) over 6 iSCSI targets isn't something I've ever seen
anyone do. Not saying it's bad, just...unique.
I just hope the OP gets prompt and concise drive failure information the
instant one goes down, and has a tested array rebuild procedure in place.
Rebuilding a failed drive in this kind of setup may get a bit hairy.
--
Stan
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