21610SA for software raid?

[TinCanFury]

Hi folks, I'm looking for a cheap way to get a 16 drive RAID 5 array built using mdadm. From what I've been able to find this Adaptec card is the cheapest way to get a 16disk controller on the PCI bus, but that it's RAID support is poor at best. What I was wondering is if anyone knows if it would be possible to use it just as a controller card (like many of the software-raid based "RAID" cards) and use mdadm to actually manage the array?

I've found an 8 port card that would work, but I would need two, which I could do, but would be more costly for the cards and in the use of two PCI slots.

thanks!

[HROAdmin26]

First Google returned this review:

The 21610SA also supports RAID0, 1, 10, 5, 50 and JBOD arrays

Further searching on Adaptec's site shows several supported Linux OS's as well as driver source code for Linux:

21610SA Drivers

I'm not sure how much more "support" Adaptec can provide.

[TinCanFury]

yea, I've seen both of those, they don't really answer my question though.

thanks,

[HROAdmin26]

The 21610SA also supports RAID0, 1, 10, 5, 50 and JBOD arrays

Please read and understand what JBOD support is.

Edit: And from a picture, it clearly has an onboard processor to handle the RAID math. I would certainly want to take advantage of any *hardware* RAID support offered by the controller.

[TinCanFury]

PCGuide - Ref - "Just A Bunch Of Disks" (JBOD)
"JBOD isn't really RAID at all, but I discuss it here since it is sort of a "third cousin" of RAID... JBOD can be thought of as the opposite of partitioning: while partitioning chops single drives up into smaller logical volumes, JBOD combines drives into larger logical volumes"

This is basically everything that I get when I google JBOD tells me.
This is not what I want, I want mdadm to be able to access each drive on its own so that it can build the RAID array.
If your trying to tell me there is more to JBOD please just say it as it is obvious Google is not pointing me directly to that direction.

[HROAdmin26]

Wikipedia has it short and sweet:

JBOD stands for Just a Bunch Of Disks (Just a Box Of Drives). Depending on the Host Bus Adapter a JBOD can be used as individual disks or any RAID configuration supported by the HBA.

JBOD support is rarely used to "combine different-sized disks into one larger disk." An decent LVM can do this. If the HBA does it, the OS would have no idea when a spindle fails (unless a software app monitors the HBA.) JBOD (in general use) is just passing the individual spindles on to the OS.

* Spindle failure notification is also an issue when using hardware RAID (again, if no app is monitoring the HBA.) But at least then you are getting RAID performance/capability.

[TinCanFury]

Ah, I see what your getting at then. I could set each drive into a JBOD mode individually and the operating system would the just see the drive. Hopefully this would not go through the normal RAID hardware as it would an actual RAID array, as this is what I'm trying to avoid with this card (apparently it has abysmal RAID speeds).

Thanks!