Software RAID failing constantly

Question

Dear all,
I need help as I cannot work out what is going wrong the the Mirrored RAID i set up.
I bought 2 x 1TB drives and setup Mirrored RAID (software) through the GUI Disk Utility Application. I assumed it would all "just work".
After about a month the RAID failied. It happened after I ran TechTool Pro 5. Could this have caused permanent damage which leads me to where I am today (see below)? I unplugged the drives and plugged into my laptop (I don't know why I didn't just unplug and plug them into the Mac Mini they were in). Anyway it came up saying "Rebuilding" and it took about 9 hours. All was good again.
Until early October 2009 when Disk Utility reported that the RAID was "degraded" and one of the drives had "failed".
I was pretty shocked as it was a new drive. I thought the best thing to do would be to get a new 1TB drive to rebuild the RAID and then deal with the failed drive.
It took over 2 weeks to get the new drive and enclosure (long story). I setup the new drive last night, plugged it in and the "Rebuilding" message came up with the same "it will take 9 hours message".
I left it over night and when I got up Disk Utility told me that the older drive of the two has "failed". There has to be something weird going on here and this is where I need your help.
Configuration
1. The drives are 1TB Hitachi 3200rpm SATA I/II, 32 MB Cache drives
2. The 'old' enclosure is an Icecube G2 SuperS 800/400/USB2/eSata 3.5" Enclosure
3. The 'new' enclosure is an OWC Mercury Elite-AL, Quad Interface eSata/FW 400/FW 800/USB 2/USB 1
4. The Mac Mini only has one FW800 port and I connect the 2 drives up in serial.
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Here is the behaviour I'm seeing now.
I'll start with both drives off and turn both on.
1. Both drives mount in Disk Util
2. 20 seconds later a message comes up about rebuilding slices for "disk1 ... ?" and "disk (null)" and disk util crashed 2 seconds later (thus why didn't catch all of the message)
3. I turn to the terminal:
bsmith@kanga ~ $ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Mini 297.8 Gi disk0s2
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk1
1: EFI 200.0 Mi disk1s1
2: Apple_RAID 931.2 Gi disk1s2
3: Apple_Boot Boot OSX 128.0 Mi disk1s3
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk2
1: EFI 200.0 Mi disk2s1
2: Apple_RAID 931.2 Gi disk2s2
3: Apple_Boot Boot OSX 128.0 Mi disk2s3
/dev/disk3
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS terra *931.2 Gi disk3
bsmith@kanga ~ $
bsmith@kanga ~ $ sudo diskutil listRAID
Password:
RAID SETS
===============================================================================
Name: terra
Unique ID: 2AC46C49-5F0B-4BD5-B1FE-C322A6F51DD9
Type: Mirror
Status: Degraded
Size: 999860895744 B
Rebuild: automatic
Device Node: disk3
Apple RAID Version: 2
# Device Node UUID Status
0 disk1s2 A12D748F-0779-4217-8C75-B31D9AE45B4E 0% (Rebuilding)
1 disk2s2 CF03D24E-AB5D-4F86-A7B1-26A1F4589CB7 Online
===============================================================================
bsmith@kanga ~ $
Run it again 10 seconds later:
bsmith@kanga ~ $ diskutil list
It just hangs.
bsmith@kanga ~ $ sudo diskutil listRAID
It just hangs.
4. Now I turn off the 'old' drive and look at the terminal (that was hanging). When I turn it off I'm told (through the Hardware Growler Growl extension to show the status of hardware) that the old drive ("Macpower"), the new drive ("OWC") and the RAID disk ("terra") have all unmounted. The diskutil commands follow.
bsmith@kanga ~ $ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Mini 297.8 Gi disk0s2
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *0.0 B disk1
1: EFI 200.0 Mi disk1s1
2: Apple_RAID 931.2 Gi disk1s2
3: Apple_Boot Boot OSX 128.0 Mi disk1s3
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk2
/dev/disk3
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS terra *931.2 Gi disk3
bsmith@kanga ~ $
bsmith@kanga ~ $ sudo diskutil listRAID
RAID SETS
===============================================================================
Name: terra
Unique ID: 2AC46C49-5F0B-4BD5-B1FE-C322A6F51DD9
Type: Mirror
Status: Degraded
Size: 319728959488 B
Rebuild: automatic
Device Node: disk3
Apple RAID Version: 2
# Device Node UUID Status
0 disk1s2 A12D748F-0779-4217-8C75-B31D9AE45B4E 0% (Rebuilding)
1 -none- CF03D24E-AB5D-4F86-A7B1-26A1F4589CB7 Online
===============================================================================
bsmith@kanga ~ $
I don't know alot about this output, though its weird that disk2 is still in the list but only shows the GUIDpartitionscheme. And its interesting that disk1 is also in the list but shows 0.0B against the GUIDpartitionscheme for it.
5. Just for kicks I turn off the 'new' drive aswell and run the commands again. When i do it Hardware Growler doesn't say anything has unmounted (I guess since they all did so before).
bsmith@kanga ~ $ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Mini 297.8 Gi disk0s2
bsmith@kanga ~ $ sudo diskutil listRAID
Password:
No RAID sets found
As expected I guess.
6. Now I'll turn both drives back on and confirm I get back to the same state I was in before after both drives were turned on.
This time I get the Hardware Growler message that both drives have mounted followed by the RAID drive about 20 seconds later.
bsmith@kanga ~ $ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Mini 297.8 Gi disk0s2
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk1
1: EFI 200.0 Mi disk1s1
2: Apple_RAID 931.2 Gi disk1s2
3: Apple_Boot Boot OSX 128.0 Mi disk1s3
/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk2
1: EFI 200.0 Mi disk2s1
2: Apple_RAID 931.2 Gi disk2s2
3: Apple_Boot Boot OSX 128.0 Mi disk2s3
/dev/disk3
#: TYPE NAME SIZE IDENTIFIER
0: Apple_HFS terra *931.2 Gi disk3
bsmith@kanga ~ $
bsmith@kanga ~ $ sudo diskutil listRAID
RAID SETS
===============================================================================
Name: terra
Unique ID: 2AC46C49-5F0B-4BD5-B1FE-C322A6F51DD9
Type: Mirror
Status: Degraded
Size: 999860895744 B
Rebuild: automatic
Device Node: disk3
Apple RAID Version: 2
# Device Node UUID Status
0 disk1s2 A12D748F-0779-4217-8C75-B31D9AE45B4E 0% (Rebuilding)
1 disk2s2 CF03D24E-AB5D-4F86-A7B1-26A1F4589CB7 Online
===============================================================================
bsmith@kanga ~ $
Now let me run the commands again:
MMM, the exact same result is returned - it didn't hang this time.
It's 21:44, I'll leave this a while and see if the rebuilding continues.
Its 13 mins later and this time the commands are just hanging. Before I went away at 21:44 the lights on the front of the drives where flashing showing something was happening. They had stopped by the time I returned.
7. Now I turn off the 'new' drive and run the terminal commands again. When I turn it off I'm told by Hardware Growler that the new drive ("OWC") and the RAID disk ("terra") have both unmounted. Last time (when the 'old' drive was turned off) Growler told me all 3 drives unmounted. The diskutil commands now show.
bsmith@kanga ~ $ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *298.1 Gi disk0
1: EFI 200.0 Mi disk0s1
2: Apple_HFS Mini 297.8 Gi disk0s2
/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUIDpartitionscheme *931.5 Gi disk1
It hangs at this point and hasn't completed yet.
bsmith@kanga ~ $ sudo diskutil listRAID
Password:
RAID SETS
===============================================================================
Name: terra
Unique ID: 2AC46C49-5F0B-4BD5-B1FE-C322A6F51DD9
Type: Mirror
Status: Offline
Size: 999860895744 B
Rebuild: automatic
Apple RAID Version: 2
# Device Node UUID Status
0 disk1s2 A12D748F-0779-4217-8C75-B31D9AE45B4E Failed
0 -none- CF03D24E-AB5D-4F86-A7B1-26A1F4589CB7 Missing/Damaged
===============================================================================
bsmith@kanga ~ $
So HELP PLEASE!. Does the above provide enough information to suggest to someone with more knowledge than me about this, what is going on and what can I do to fix this? Let me know if there are any more tests I can run.
I have a backup of the data so can erase and recreate the RAID drive. But what would stop this happening again? Could it have been TechTools Pro 5 which was running when the problem first happened that caused some permanent damage?
Any and all help appreciated.
Thank you,
Brooke

Answer 1

Thanks ridogi and Antonio for your replies,
For clarification, both drives have dual FW 800 to allow them to be connected. No FW 400 involved (I'm not that silly .
I can't say i've done extensive research into setting up RAID drives but I've never come across advice to not use multiple external drives. Here is an extract from a Nov 2007 MacTech article on using RAID for backup:
{quote}
The Desktop Mac User:
The second user I want to look at is the professional who relies on his desktop Mac for his business. He is a lawyer, developer, architect or other professional whose business relies totally on the contents of his computer. If he loses the files on his computer, his business will really suffer. In addition, the time lost when dealing with a failed hard disk is money down the drain. This user relies on a three disk mirror volume. His Mac has two internal SATA disks which are used as the primary and secondary disks of a mirror volume. If one of the disks fails at any given point, the other one will take over and become the new primary disk, so his files are always protected from a hard disk failure. The third disk is an external FireWire disk which is also a secondary disk. It is stored offsite (either at home in a fireproof safe or at another safe location). Every Friday, he brings this third disk into his office and connects it to his desktop Mac. Once this disk is connected, a mirror rebuild starts automatically. He can perform this rebuild as he continues to use his Mac during the day. At the end of the day, when he shuts his Mac down, he disconnects his external secondary disk and returns it to its offsite location. This offsite secondary disk becomes his insurance against his building getting broken into or his building burning down. Like the laptop user, if his Mac gets destroyed, he can just purchase a replacement Mac and then boot up from his external secondary disk. At most, he will use one week's worth of work.
{quote}
So I just assumed it is ok to use external drives. This is discussing a software product called SoftRAID and perhaps that is able to handle the situation. Or perhaps one external drive is ok???
My plan, developed when deciding to buy the Mac Mini April 2009 was to amortize costs by buying external drives first for doing backups and then buying a NAS within 12 months. I guess I should have just gone the NAS.
However ridogi I see you've recommended WiebeTech which don't seem to have NAS devices but DAS (direct attached storage) as the devices are connected directly to a network machine via Firewire etc. (Whereas NAS connects via the Network - I'd connect such a device to the Airport wireless router). Do you prefer DAS over NAS? I guess the downside of NAS is that the complexity is somewhat greater.
And reading http://www.wiebetech.com/just-say-no-to-nas/ they say:
{quote}
Let's face it - Networked or "shared" storage is a great feature but most NAS devices are just too slow for many applications. 3MB/s for a NAS device is common and 10MB/s is considered fast. Direct Attached Storage (DAS) performs much faster while still having the ability to be "shared". The RTX400-QR can transfer data to your computer at speeds exceeding 100MB/s.
{quote}
How can this be? If connected via Gigabit ethernet (128MB/s) then isn't that faster?
Though it is true that if you connect via Wifi then the best speeds you are going to achieve is 6.75 MB/s (802.11g) or 17.5 MB/s (802.11n).
Of course the speed advantages for DAS are only going to be on the machine its connected to as the other machines will connect to it (via the machine its on) over the network anyway!
Why I like the idea of NAS is to move the drives away from the Mini (noise and powerpoint reasons), make it easier to share with other Macs/PCs in the house (including via SMB) and I have a vague hope that this might stop the delay caused by the connected external drives spinning up when an open/save dialog box is activated (or is this just me?!).
Your thoughts appreciated! And thanks for the help so far.
Cheers,
Brooke