Q: Ambiguous RAID failure
Early 2008 Mac Pro with Apple RAID card and 4 x 1TB drives installed.
I've had yet another RAID failure on my system (it's happened several times before) but this time the diaganostic is ambiguous and I need to make absolutely sure what's happened before I try to recover from it.
Overnight the RAID Utility log reported that Drive 3 had failed, that Raid Set RS1 was now degraded, and that there was no spare available for rebuild.
When I look now in RAID Utility at the status of the drives and of the array, all four drives show "green" (SMART: Verified and Status: Good), and Raid Set RS1 is "Viable (Degraded)". But it shows the drives in Bays 2, 3, 4 as "Assigned" to Raid Set RS1, while the drive in Bay is not: it shows as "Roaming".
I'm fairly sure that one of the drives actually is problematic, because I've been having increasingly frequent episodes of freezing and non-responsiveness on the system (spinning beachball). In the past couple of days it got so bad that it was difficult to do anything at all following a restart; the freeze/beachball happened very soon after. I remember now that I had exactly this symptom in the past, just prior to a drive failure that RAID Utility reported.
So I guess I need to replace one of the drives, mark it as "Spare" in RAID Utility, and let the array rebuild.
But WHICH drive should I replace? The log says that Drive 3 failed (I'm assuming that "Drive 3" is the drive in "Bay 3"), but now that drive shows as "good"--as do all four drives. It's Drive 1 (i.e. the drive in Bay 1) that's been taken out of the array; drives 2, 3, and 4 are in Raid Set RS1. Is that a red herring? Is it possible that Drive 1 is bad even though the report was about Drive 3? (Drive 1 is the only drive that has never been replaced at any time in the four years since I got this system.)
I think/fear that if I replace Drive 3, I'll blow away the array.
So it seems to me that I should rebuild the array by marking Drive 1 as spare (since it's the only drive that's unassigned), wait for it to complete, and then replace Drive 3 and rebuild again. Or maybe I should just replace Drive 1 pre-emptively.
I don't know, but it takes a full 72 hours for the re-build to complete, a nerve-wracking time because throughout it the system is vulnerable to a second drive failure, so I would prefer not to have to do it multiple times.
Can someone please tell me in detail what the safest/most correct way is to proceed in order to recover from this?
Thanks.
Mac Pro (Early 2008), Mac OS X (10.7.4)
Posted on May 18, 2012 8:39 AM
Think we've kicked this dead horse into the ground enough.
Truthfully, I'd try to sell you on external RAID6 for hardware array box.
Software (SoftRAID) for inside.
PCIe SSD card(s) for high speed I/O
MacGurus for their options and forum
https://www.macgurus.com/forums/index.php
www.macperformanceguide.com
for setup and upgrade options - he recently went with PCIe SSDs and 4 x 4TB Hitachi using half each drive to achive as much I/O as a Mac Pro can get on native 4 SATA drive ports.
I would reload your data, just not to the Apple RAID controller array.
And close this thread.
Posted on May 27, 2012 10:51 AM