RAID of RAIDS - mirrored RAID 5 -

We bought a Promise SX8000 and configured it as RAID-5 with a hot swap spare to prevent data loss... Then 3 drives failed and we lost the data ;-) So we sent out emails saying the database was down because:
"we purchased a very large expensive highly redundant storage device which failed.. so we yelled at promise who is sendind us a second very large expensive highly redundant storage device so that we can make one out of the two in hopes it works"

Ok, I have heard reference to things like RAID-52 at such, (redundant raid 5's) but my queston is this..

If we have 2 Promise SX8000 external RAID's configured in a RAID-5, each about 1TB and we wanted to mirror one to the other, where do we start? We thought we could just buy a card, and hook up both of the Promises to it, so we did... The card sees the devices, but wont make a mirror out of them. We called Promise who said no, it couldnt be done - thay had tried a RAID-5 of RAID-5's which failed miserably - so we called Adaptec (the card we bought) who said it was promises fault, their devices werent presenting themselves as SCSI devices and of course Promise says they are.

Has anyone ever set up somethign similar to this, or have an Idea where to send me? Currently we are going to have to write some cron josb to backup one to the other at midnight, meaning if we fail we only lose the current days work - but it seems like there is a better way to do this..

wow, that is a big problem. I wish I had any idea about RAIDs.

That's not good - I was hoping in your database world you had looked into something like that..

I mean RAID-5 is supposed to keep you safe in the first place... so it seems like overkill, but after you lose a TB you will rethink you rprocess too.. I mean we have DVD backups and such, but its a pain in the A*S to backup a TB and even more of a pain to restore it from those tapes/DVD's...

I am no expert in either Linux or *BSD, but I have read about something FreeBSD offers called "vinum" which, as I understood the description, sounds like it might be able to do something like what you want. I don't think I have ever seen anything of the sort for Linux. It might be a lead to something useful.

rexfelix - thanks, but we are hoping for a hardware (mostly) solution - at the moment we have settled for 2 RAID units and a rsync

for a (relatively) small fee I am sure I could come up to your work and get it happening :) I learn fast enough to know what is up.

Ah, yes, you did mention you wanted a hardware solution, didn't you? I think I have too many programs running and distracting me. lol

Wow what are the chances of 3 drives failing(never buy cheap hardware from a cheap store). Anyway I would look at a san with raid 10 which would work much better. I am not sure what your budget is though, a nas would be a cheaper solution but a san would work so much better for this.

they were brand new WD 200GB drives, we had issues with them failing, and the Promise controller said they tested them with the 200's, but they only tested the 4 drive controller, not the 8

budget kinda plays into it to, as does stupid people. See the other network guy thought he could build a raid chepaer, so he bought these drives, and some adaptec cards, which didn't support the 200GB and conflicted with the onboard controller. So in the long run he then bought a SX8000 to make the drives still a useful purchase, me - i wanted to buy a nas back then and get it over with

If that's hardware RAID-5, I don't think you can just make it a RAID-25 or RAID-52 directly. What I'd do is that I'd take those two HW RAID-5 arrays and software-RAID them together into a software RAID-1 array. What do you think of that?