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Goodbye Areca, Hello LSI

SysOp — Fri, 25 Jul 2008 17:26:31 +0000

While it’s not clear exactly who-is-causing what, what is clear is the areca driver tries to de-reference a NULL pointer, this is either because the adapter screws up, or the driver screws up somewhere. The result is a Solaris kernel fault, pointing at the arcmsr driver, and apparently an adapter lockup. It’s not 100% clear what causes this condition. It could be the driver not handling some buffer appropriately, it could be the card sending an error that the driver doesn’t handle. It’s pretty likely though the issue is completely inside of the arcmsr driver and Areca hardware. One thing we did discover that means we HAVE to replace the Areca hardware is that in JBOD mode (which is how we use it, since we’re using Solaris’ ZFS superset of RAID functionality), any disk failure seizes the whole card up until the failure clears, or maybe until some apparently long timer clears. SATA and SAS have ethernet-like link failure detection. You know within milliseconds when the cable is pulled. The Areca’s in JBOD mode seem unable to handle hot-swap of any type, or even failures of any type. When we tried to get them to address it all we received was vague “you must have a failing drive” answers, which for a RAID card is a bad answer. Even in JBOD mode the controller should signal/propogate an error. Solaris’ would handle this condition.

Then there’s the boot selection. All logical drives appear in the boot selection. Either the list fills up or the Areca’s only show drives on the first controller. That’s a problem if you want to be able to boot an alternate drive on a second controller.

So, Saturday, I get to backup the entire user data. Blow the whole damn thing away. And start over. *sigh*

I know I posted about this before, but we were avoiding the whole rebuild thing, turns out I’m going to have to do that anyway. Argh. The biggest reason is the LSI cards use an on-disk metadata format (apparently). They’re kinda quiet about it all so I’m not sure how big it is or where on the disk. I’m betting it’s the last N megs of the drive. 8, 16, 20 something. Most people won’t notice, but if you’re migrating, it becomes noticeable.

Where’s the RAID? I’ve still got a bug!

SysOp — Fri, 15 Feb 2008 01:34:31 +0000

Some days it’d be nice to be a cockroach, life would be simpler that’s for sure. So in a previous post I mentioned the trials of getting an ARC-1280ML working with 16+ drives in JBOD. We’ve decided to go with a pair of the same controller, less ports the ARC-1231ML. Hopefully they’ll fix the limitation at some point. So we’re waiting on that new hardware. Keep in mind there’s nothing really *wrong* with the ARC-1280ML, it’s just not going to do what we need it to do.

Taking the card out, btw, felt a bit dodgy. It’s a heavy chassis, with 24 3.5″ 10KRPM 73GB SATA drives in it, 5U tall. It’s mounted fairly low in a full rack, but still, it’s heavy. I slid it out on it’s rails while standing to one side just in case. I’ll have to take a picture sometime for you guys to see what I’m talking about, maybe when I update and put the 2 controllers back in. I am 99% sure the racks won’t come over, but still. It feels unnatural.

It’d be great to get a Darwin for that one I suppose.

RAID, no, not the insecticide, though there is a bug here.

SysOp — Thu, 07 Feb 2008 01:57:46 +0000

Areca ARC-1280 (and ARC-1280ML’s, same product, different connector) have 24 SATA ports. But only support 16 drives in JBOD mode….or in any mode really, 16 drives exposed to the host is maximum. The controller deadlocks during POST/INIT if you have 17+ drives when it’s set to JBOD mode. So you can have 12 LUNs 2 drives each (mirrors) or some other combination of RAID, but you can’t do JBOD with 24 drives as of the most current (1.43) firmware.

I’m waiting to hear back from them exactly why this is. At least this one isn’t affecting our rollout of anything, but if there’s no “fix” for this controller it means trading out to 2×12 or 1×16+1×8 port controllers or something like that. Not a big deal for us for this operation since we plan to use Solaris ZFS which has integrated RAID with transactional support and because it’s totally integrated into the filesystem it really appeals to me as something that could be (and probably is) very reliable. They’ve also taken a lot of steps to produce a filesystem that is an order of magnitude more reliable and better at ensuring data integrity than almost anything readily available for production.