which vendors have RAID 6 SCSI adapters

Posted on 2004-10-02
Last Modified: 2010-04-03
Hi - I'm looking at getting either an IBM server or HP server and I'm wondering whether either of them have RAID 6 SCSI adapters.

I want to set up a 14 HDD external enclosure (IBM EXP400) but want to have RAID 6 with two hot stand bys so that i can support two disks failing simultaneously.

Does anyone know if IBM or HP have such adapters for SCSI DAS storage?  does anyone know model numbers?
Question by:kenshaw
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Expert Comment

ID: 12210844
IBM x235 TS is your answer;



Author Comment

ID: 12210865
what do you mean?  is that the model of the SCSI adapter?  isn't the x235 a tower server?  are you saying that it has an adapter that supports RAID 6?
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Expert Comment

ID: 12211033
It is a Tower Server with all the specifications you wanted...

It has a built-in RAID 6 controller and forth...


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Accepted Solution

andyalder earned 250 total points
ID: 12211376
HP Proliant smart array 6400 supports double parity, they call it RAID ADG rather than RAID 6 (IBM call it RAID 5E) but it's the same thing. Be warned though that double parity means 6 I/O operations for each write rather than the 4 I/Os per write of RAID 5 and the two of RAID 1. This is not as bad as it seems as the controller is battery backed so some of those I/Os don't really happen but get cached instead. Their cheaper controllers are only RAID 1, 0+1 and 5.

They are not hot standby drives, they are part of the array. A hot standby is an extra spare drive on the shelf so that if a drive fails the array gets rebuilt without you having to physically swap it out. With the HP controllers the hot spare is normally powered off, the controller spins it up now and again to see if it is working then spins it down again. Probably IBM do the same thing.

I wouldn't mix and match though, if you already have the IBM shelf I'd buy an IBM server either with integrated controller or an additional IBM controller. If you go for HP then you should use the equivalent shelf from HP, i.e. the MSA30 rather than the EXP400. If not and you lose a whole scsi channel who do you call out? if IBMs shelf is faulty and you call out HP warranty they'll charge you and the same if HP's controller is faulty and you call out IBM. I would recommend a dual bus shelf, costs a bit more to have 2 SCSI channels but 14 disks is a bit much for a single channel to support, you can spread the array across both channels.

Since you have rack storage you'll be wanting the IBM X345 plus a controller or the HP DL380 plus SA6402. You should think about spending about $1000 on the controller, you need that battery backed cache and it isn't cheap. Note that DL380 comes with integrated 5i controller but it doesn't support RAID 6, only 0,1 and 5. You normally use it for mirroring raiding the internal disks and use the other channel externally for tape backup.

You might get away with a 1U server but they are very noisy and there's hardly any difference in price.

Cyber, are you sure the x235 has an integrated RAID controller? the specs say it has a dual channel U320 controller but say it only supports RAID 1.

Have you thought about NAS instead of a server as it's just for a fileserver? They're often the same thing, HP's NAS 2000s for example is a Proliant DL380 with a plastic grill over the front to disguise it and windows storage server 2003 preinstalled. As long as you already have domain controllers NAS would be cheaper, if you haven't got domain controllers then obviously NAS won't do.
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Expert Comment

ID: 12211475
andyalder, yap Im sure. You ware looking at the x235. I was talking about x235 TS (that model has an integrated RAID 6 controller - according to IBM's deallers).


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