On Sep 17, 2009, at 8:33 PM, Gianluca Cecchi wrote:
On Thu, Sep 17, 2009 at 11:42 PM, Michael Tokarev <[email protected]>
wrote:
Gianluca Cecchi wrote:
[]
And what about instead do somthing like this:
- sda and sdb on both nodes
- raid0 on both nodes so that on eac node you have one md0 device
- only one drbd resource based on md0 on both
This is wrong. If either disk fails, whole raid0 fails,
ie, half the thing fails.
With reverse approach, ie, two drbd resources on top of
disks, and raid0 on top of drbd resources - if any disk
fails only that 1/4 of whole thing fails.
It's classical raid10. It's always done like
disk => mirroring => striping, but never like
disk => striping => mirroring.
- use drbd0 device as PV for your VG
- add clvmd to your cluster layer (you need cman too for clvmd)
I'm doing it but only with one disk per node
With one disk per node it's simple raid1.
/mjt
My approach is done in reality and is named raid0+1, while the
initial post one is socalled raid1+0 (aka raid10 as you wrote)
See also http://en.wikipedia.org/wiki/Nested_RAID_levels
BTW: in general, failures to take care of happens not only at hw
level (hard disk in your comment) but also in sw (in the scenario
here, possibly in sw raid layer or drbd layer, for example)
Gianluca
I'm not so concerned with raid1+0 vs raid0+1 but the use of striping
on the same volume between two active nodes. Any pros/cons for md or
lvm striping? Or more specifically, are they considered safe in this
setup or will corruption slowly come about?
--
Matth
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