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Old 01-09-06, 01:50 AM   #4
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Join Date: Jan 2005
Posts: 135
Default Re: mdraid vs. dmraid benchmark and Intel RAID0/RAID1 on same pair of drives

I do have links(ithink...) but they are on a different unaccessible OS.
The method is simple to create a 3 disk RAID 1+0. Create a RAID 1 array and then use that RAID array as the second volume for a RAID 0. I have no idea how safe or good it is.
...Terrible explanation, I know. Sorry.
The steps are in a RAID forum, the name of which I cannot recall since I have not looked at it for over a year... but it is all about dmraid and the md application. IIRC, the author of dmraid announces new versions in that forum.
You will have to hunt for it -google is your friend.
For example, 2-way mirroring on 3 drives would look like

A RAID 10, sometimes called RAID 1+0 ...
[ there is a diagram at the link; making one here that looks decent is too hard]
(NOTE: This is why Wikipedia sux; RAID 10 is supposed to be 1+0, a stripe of mirror, but just about every vendor reverses it so RAID 10 has become RAID 0+1, a mirror of striped disks, but they don't bother to tell you that. -> Never trust a vendor that says they have raid 10 w/o defining what it is.)

AS for making a disk part RAID 0 & part RAID 1, the only way I think that could be done would be by using EVMS.
I have never done that although I have had swap on a RAID array. The swap is always swap no matter where it goes.
EVMS does have a mailing list that is used for Q&A as well as dev., annoucements, etc.

To get good answers to RAID questions, a forum dealing with RAID would be a good location. Obviously NV does not care to assist... and I (obviously, too) am no expert.

Good Luck!

PS: Thanks for that link! I will give it a look later.
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Last edited by fhj52; 01-09-06 at 02:30 AM.
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