Forum OpenACS Q&A: Re: OT: Dell PowerEdge RAID 10 Configuration

Posted by Andrew Piskorski on
AFAIK "RAID 10" can be done in two different ways, 1,0 or 0,1. Either your mirror first and then stripe (10), or you stripe first and then mirror (01). Presumably 10 is better than 01.

James, Dell's RAID 10 info sounds confused to me. Actually, it reads as if it was written by a secretary after taking notes on something she didn't actually understand.

From the above it is not really clear just what the hell their "RAID Level 1-Concatenated" is, but they presumably mean that it is atually RAID 10 done in 1,0 fashion, which would be good.

But their info above is all confused, they are mixing together discussion of hardware and software RAID without ever explicitly saying so, the whole sentence about "In a concatenation ... the entire volume becomes unavailable." is misleading and only partially accurate, etc.

Posted by James Thornton on
BTW: Since LSI makes all of the current PERC4 cards, I called LSI yesterday and asked them about the PERC4-DC's support for RAID 10. The tech I spoke with said that the PERC4-DC is an LSI MegaRAID 320-2, and it has full support for RAID 10 as does the PERC4-Di card so Dell's documentation is apparently wrong.

Also, Matt Domsch, a Dell lead software engineer, confirmed that hot the PERC4-DC will support a global hot spare using specific software from LSI, but you have to manually configure this to do so. Since hot spares are per-controller, not per channel, it's fine to have a hot spare on the 3 side in a 2+3 split channel configuration. If you lose a disk on the 2-side, it'll rebuild onto the spare such that you'll really be running with one channel with one disk plus a bad disk, and the second channel with three disks.

Posted by Andrew Piskorski on
For the record, I think Dell's docs, as quoted above, are technically "correct", in that they don't seem to actually contain any factual errors per se. It's just that they're so poorly written that it's almost impossible to draw any correct conclusions from them!

Clearly you did the right thing by tracking down the real info from the manufacturer.

Posted by Paul meiners on
"misleading and only partially accurate"
Just a note on Dell...
Dell's definition of raid 10 is NOT the industries standard, the jerks at Dell find it better to keep customers totally confused; confused mushrooms are good for business.
Dell's definition of raid 10 is raid 0+1, which NO one should use, as you can only loose one drive, the second is total array loss. The newer Percs are LSIlogic, and are quit capable of doing industry defined raid 10 (mirrored and striped) or raid 0+1 (stripes mirrored). Anyone confused should go to and follow their raid 10 setup..
Posted by Mark P on

I have a Dell 2600 W Perc4/Di. I called LSI and they said that all they do is supply chips for these cards and Dell does ALL the software for them. He said that if you use LSI software on these cards, you can destroy them. He said contact Dell only for any issues with these cards.

So, Dell says that this controller does RAID 1 - concatenated. I DO NOT believe this is a true raid 10!!!!

RAID 1 concateneted does not stripe, it just fills multiple drives in 1 array, 1 at a time, and then mirrors them.

What the heck it this????

Can a CONCATENATION professional comment here?