5 Replies Latest reply: Sep 22, 2011 5:16 PM by TommyH
TommyH Level 1 Level 1 (0 points)

Curious on what to do with a RAID 1 Drive (s) failure? I've searched the community and cannot find similar issue/answers.

 

Configuration:

One 1TB OS & App Drive is fine

Two 3TB RAID 1 Drives for Video scratch are fine

Two 2TB RAID 1 Data Drives are my issue

     I'm using the software raid in OSX and it shows "2TB Data Drive/Mirrored Offline"

     Both drives have "Failed" next to them

 

I have backup this Data Drive in Time Machine and a recent full back up to a single drive that is off site.  I believe I have a good back up strategy with Time Machine and offsite back ups via Voyager S3.  I guess we'll find out!

 

My question is how do I find out if it's a HW issue or SW issue with this configuration ?  And then how to go about recovering them?

 

Initially when I looked in Disk Utility it appeared that only one of the 2TB drives had "Failed" next to it but now after a reboot "Failed" is next to both drives.

 

My initial hope was that one of the drives had failed and I'd be able to just replace that drive and the RAID System would rebuild from the other drive.

 

Any assistance would be appreciated.

Thanks


Mac Pro 2010 12GB RAM, Mac OS X (10.6.7), PowerMac G5 PowerPC, MiniMac
  • ds store Level 7 Level 7 (30,315 points)

    TommyH wrote:

     

    My initial hope was that one of the drives had failed and I'd be able to just replace that drive and the RAID System would rebuild from the other drive.

     

     

    RAID 1 just copies the same data to two (or more) drives at the same time, it's only for mission critical data loss requirements where a drive failure during writing would be catastrophic. Like taking purchasing orders or getting a phone call from ET for example.

     

    RAID 0 is dangerous as the data path is separated to how many drives in the RAID 0 set, one drive glitches and all data is lost. But provides insane speeds.

     

    RAID 5 is a much more reliable, it combines many drives (4 or more for more speed) splitting the data path but also has redundancy factor that if a drive dies it can be replaced and the data is recovered from the other drives. Usually a RAID 5 is in a external enclosure with it's own cooling and hardware controllers, not software based RAID where your CPU is being overloaded.

     

     

    There are other forms of RAID some combinations like RAID 1+0, RAID 6, 10 and so forth, you can find out more about the more eclectic RAID types online.

     

     

    RAID 5 is more ideally suited to video requirements for data storage, with perhaps a RAID 0 as a scratch disk or a RAID 0 + 1 (the RAID 0 is mirrored to another RAID 0) if your going to take a while working on it that increases the potential of failure.

     

    Once the work is completed, it's sent to the RAID 5 where it's safe with it's redundancy and speed.

     

    http://eshop.macsales.com/shop/hard-drives/RAID/Desktop

     

    The thing to remmeber with the failed RAID 1 Data drive is the data is still on the drive, even though it failed and perhaps things are messed up a little on it on the directory. All the drive needs is to be told it's not part of a RAID 1 anymore, that it's a normal drive, a simple fix, but I don't know how to go about it.

     

    You have two drives and two chances to recover the data off off, simply disconnect one data drive and reboot, see if it will mount and or you can repair the drive in Disk Utility.

     

    If not pull one drive out and stick another blank one in there and download Data Rescue and simply recover the files to the new blank drive. DR works by simply reading the files themselve, not the file struture or anything else.

     

    Software RAID is unreliable, it depends upon the CPU. Opt to get a external RAID where it's based in hardware instead. Use eSATA if all possible.

     

    Also consider using backup software, like Carbon Copy Cloner which can be scheduled to make a backup of your data during the middle of the night. This way if something happens to either your boot drive or a data drive, the clone won't immediately copy the issue to the other drive like a RAID 1 does.

     

    Also Carbon Copy Cloner makes "hold option" bootable OS X boot drive clones, which TimeMachine doesn't.

     

    Also TM kicks in what, like once a hour? It's likely what caused your issue, CCC will work when you schedule it.  TM is for consumers, not video pro's like yourself.

     

     

    If you need even heavier iron as a external RAID setup and more expertise, then see these guys

     

    http://www.macgurus.com/

  • TommyH Level 1 Level 1 (0 points)

    Thank you I will try the remove and replace with another drive and let you know if that works.

     

    You mentioned:

    Also TM kicks in what, like once a hour? It's likely what caused your issue,

     

    What makes you think TM was the culprit?

    Thanks

  • TommyH Level 1 Level 1 (0 points)

    My current drives that may have an issue are this model from WD: WD2001FASS

     

    I need to buy a new drive(s).  I can buy the exact drive that is Western Digital Cavier Black WD2001FASS or I can buy the more current version WD2002FAEX.  Both of which are 2TB. 

     

    However one has a speed of 3 GB/S vs new one with 6 GB/S. 

     

    Will it matter? 

  • ds store Level 7 Level 7 (30,315 points)

    TommyH wrote:

     

    My current drives that may have an issue are this model from WD: WD2001FASS

     

    I need to buy a new drive(s).  I can buy the exact drive that is Western Digital Cavier Black WD2001FASS or I can buy the more current version WD2002FAEX.  Both of which are 2TB. 

     

    However one has a speed of 3 GB/S vs new one with 6 GB/S. 

     

    Will it matter? 

     

    For recovery only, it doesn't matter what the second drive is as long as it's large enough to hold the first drives data.

     

    If you intend to RAID again, the drives should match. This may mean buying two drives as they get updated even with the same name.

     

    If you don't RAID the data, instead use backup software at night to clone A to B, then it doesn't matter what the second drive is as long as it can hold the data from the first.

     

     

    So it's better with a data drive to clone at night, this way you get the advantage of time, just in case you accidentally delete something or have a issue related to the drive, you can switch to the second drive and/or recover from it.

     

    I can perhaps understand why your scratch drives are RAID 1, but not your data drives, those should be cloned/backed up nightly instead to avoid the issue you just experienced, that both drives fail at the same time due to a software error being written to both drives at the same time.

     

     

    You can use the free MacTracker to look up your machine and it's maximum SATA speed, obviously if you have a SATA 3 and SATA 6 on a SATA 6 Mac in a RAID 1 it's going to default to the SATA 3 speed.

     

    If you have a SATA 6 on the Mac, and the older drives are SATA 3, then buy a SATA 6 new drive and use that as your primary data, then clone the SATA 6 to the SATA 3 at night where time doesn't matter.

     

     

    TM could have been your problem it might have not been, however ALL people using hard drives for video and even audio should Disk Utility Erase with Security Option Zero ALL new drives once before using. This forces a bit by bit check and any bad sectors are mapped off permanently beforehand, it results in a much more reliable drive especially for large file needs as they cross more sectors, thus have larger chance of file corruption.

     

    If your running a RAID 1, means the data your storing is extremely important one time recording option only that it has to be duplicated right away.

     

    If you set your computer to spin the drives all day and night, they perform more reliably than if you turn then on/off  as this causes them to heat up and cool down, which creates stress and glitches.

     

    If you buy the better Hitachi enterprise level drives you pay more, but the drives last a lot longer and are more reliable than the more consumer level WD and Seagate drives.

     

     

    To get some more current advice, as I run laptops now instead of desktops, you should see the Hatter, he usually hang out in the Bootcamp forum.

     

    https://discussions.apple.com/people/The%20hatter

  • TommyH Level 1 Level 1 (0 points)

    Great feedback on many fronts thank you!

     

    I'm going to make that change for my Data drive...move from RAID to Cloned drive set up.

     

    As you suggested, I removed the bad drive and rebooted and could see the Data Drive. However the Data on it was quite old...only up to April which is very odd.  Any idea why that would be that old?  Shouldn't it be up to date?  I believe I have the data on my TM back up and on another back up I have as well.

     

    Thanks!