Re: Docs and operation of RAID10, size limitations on 0.90

On Wed, Jul 30, 2008 at 08:29:07PM +0200, Keld Jørn Simonsen wrote:

On Wed, Jul 30, 2008 at 12:18:06PM -0400, Bill Davidsen wrote:

quoted

Richard Michael wrote:

quoted

Hello list,

I'm building a new system with 8 disks, in two RAID5 arrays of 4 disks
each, and a RAID1 array across them.  (Then LVM2 on top of the RAID1
array.)

I approached it this way for two reasons:

1/ It feels "cleanest"; in the sense that it's not a special case, it's
just RAID1 with two devices, which happen to be RAID5.

To me it seems muddy. Just having one big raid5 or raid10 would be cleaner and
give better performance.

I can't have one big RAID5 because I want to split it in half
regularly.  I refer to it as "cleaner", because it treats the devices
separately, which is what they are; one is RAID1 device, the other is a
RAID5 device.  Each is agnostic, and independent, with regard to the
other.  "Muddy" in my opinion is a mdadm hybrid RAID10, of which I need
special knowledge.  YMMV.
 

quoted

quoted

2/ I have a particular usage in mind: I need to be able to split
the mirror and remove half; return it later and resync.  Therefore,
I want to know which disks comprise which halves.

I am not sure what you mean with this. You want to remove half of the
disks? I think you can do that with raid10, you just remove every
other disk. I have not tried that out, however. You could try it out
before actually emplouing it.

Re-reading what I wrote, it's a mess of typos. :)  But, yes, I want to
remove half the disks on a regular basis, as off-site storage, and return
them to the array for periodic resync.

Regards,
Richard
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