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Thread: Unable to rebuild Raid5 - Lycom Sil3124, Mac Pro

  1. #1
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    Default Unable to rebuild Raid5 - Lycom Sil3124, Mac Pro

    I've tried about everything I can, so I'm hoping someone here can help.

    I have a early 2008 Mac Pro. I bought a Lycom (?) Sil3124 card from MacGurus in 2009, and used it with a 5-bay Rosewill enclosure. After a few hiccups it had been working fine for all these years. I was using it for two Raid1 disks and one non-raid disk, all set up within the MacOS "Disk Utility" application.

    Recently I reconfigured my backup strategy and needed to use the enclosure as a 4-drive Raid5 disk. Disk Utility doesn't support Raid5, but I remembered that the Lycom card did. I downloaded the SATARAID5 utility (Java-based) and used it to set up the disk - four 1TB drives into Raid5. Everything worked fine and I was able to copy a bunch of files over onto the drive.

    That was about 3 weeks ago. Early last week I found that the disk wasn't mounted anymore, so I fired up the SATARAID5 utility. Only 3 of the 4 drives showed up. Long story short, it appears that one of my drives completely died. I've tried it in other enclosures and I can't get it to mount or even be recognized.

    So, the whole reason I did this in the first place was to mitigate this exact problem. Raid5 is supposed to allow one drive to fail, and by replacing it the Raid system will rebuild it and put you back in business. In my case, this did NOT happen.

    I've read and re-read the Silicon Image documentation, but the utility application is not doing what it is supposed to do. It shows the 3 good drives, and reports that they are part of a 4-drive set, but the menu commands that are supposed to repair/rebuild are continually greyed out.

    Here is the main window:


    And the two menus I get:




    For now I'm stuck, and I'm annoyed that this expensive endeavor to provide data security has appeared to fail completely. I'd love to hear from anyone that's used this RAID configuration software and had luck with restoration of a RAID group. I'll be happy to follow up with any additional information that is requested.

    Thanks!

  2. #2
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    jswayze

    Oh boy. That sounds like a bad day!

    While long ago I did some testing of the Silicon Image RAID5 software, I found it, like pretty much ALL firmware RAID5s, to be like trying to climb half a ladder, it just doesn't have enough substance to do the job. I have always shipped all Silicon Image cards with a warning that on Macs not to use the RAID5 software. And if I were to talk with someone about on a PC, while it is more stable than on a Mac, it is still sadly lacking in capabilities.

    There are no real recovery tools with this type of RAID. And like a Drobo, or LaCie RAID or other like plethora of RAID5 units that are sold as 'data protection' devices, it does anything but provide data security.

    RAID5 is incredibly complex at the drive level. If something scrambles the RAID5 engine, the data is gone. Doesn't matter if the RAID was created by a $200 host card or a $20,000 Enterprise RAID system, if the software is confused then the RAID is hosed and absolutely no one can put it back together again.

    I am not a proponent of ever considering RAID as "adding data security". RAID5's only real purpose is the possible convenience of continuing to operate through a drive failure and giving the administrator time to drop in a replacement drive and rebuild from the parity data. As stated, it is complex and the possible failure points, and likelihood of a data loss failure, are just as many as a RAID0, just different.

    High end RAID5 controllers, ie: like a $1000 ATTO 1680 SAS card, most of the actual cost is not the hardware but the administrative software. That software takes years to have enough maturity to be considered usable. Usable means that the software was written to account for handling most any conceivable failure event.

    That SIlicon Image software RAID5, and LaCie or Drobo et al, all have in common that they virtually skipped the entire management utility altogether. So recovering from pretty much any failure is a matter of flushing the RAID and rebuilding it and then copying the data back from backups.

    No RAID, no matter how high end, can be considered 'data security'. That is not its purpose. Only a backup is data security. I especially don't trust mirrors as I have seen many a mirror get corrupted through a drive failure of the other component drive. RAID1 mirror drives are siamese twins and they again, only add a very small protection from maybe a drive failure. Once again, backups are a much better solution unless you have a lot of users all dependent on the data. IN that case, you still need a backup but the mirror or RAID5 make administering the data much simpler since you can put off immediate drive replacement in event of a failure.

    Wish I could tell you a trick to recover your RAID. I really do. And you might find a method that will rebuild the RAID. I just don't have much faith that that particular RAID is capable of handling this problem and recovering. It looks like it is scrambled.

    I am here to help though, if there is a way out we'll find it.



    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  3. #3
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    So, it sounds like the RAID does not mount now, and the data is not visible?

    If not, I don't have any suggestions.

    Rick is right here: you should be able to see your data now in the degraded state, and you should be able to add a drive back in. If you can't....

    Odds are not good there are any tricks out there, outside of Lycom knowing what (if anything) can be done.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  4. #4
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    Thanks for the insight guys. I suppose it was a bit naive of me to assume data security with a RAID5, but I thought (and I think rightfully so) that it should have "just worked". Luckily I had my data backed up online, so as long as CrashPlan doesn't let me down, I should be OK.

    I've also written to Lycom in Taiwan and they've already responded back, so that's encouraging. Hopefully they'll be able to give me a little more information.

    Overall though, I feel let down by the concept of RAID5. With several backup methods in place, I see no advantage to a 4x1TB RAID5 setup vs. a single 3TB external hard drive. Once I get my situation cleared up I'm going to switch back to a RAID0 or JBOD and rely on by backup strategy to mitigate future failures

    This also makes my decision easier with regard to replacing my 4+ yr-old MacPro. For me, a 27" iMac (whenever it gets launched) will cover all my needs, including storage which can all be handled externally.

    If I get an actionable response from Lycom I'll follow up on this thread in case anyone else has a similar problem.

    Thanks again,
    Jeff

  5. #5
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    What does RAID5 give you:

    #1 - Big fast volume (as long as the controller is fast)

    #2 - With Enterprise level you gain a modicum of protection from a drive failure. Meaning you just possibly may be able to continue to use it until you take a moment to replace a failed drive.

    #3 - Expand it later - a capability present with high end RAID5 utilities.

    #4 - uh, there isn't a number 4. (data security is not on this list)



    I have been building testing, writing about, and selling storage for 15 years. In the lab here at MacGurus we own enough parts, pieces, cards and systems to build a small scale server farm. I have in my own workstation a few thousand dollars worth of high end Enterprise quality RAID5 controller cards for testing and for support, at all times. Yet all my own storage, and everyone else's at MacGurus, is simply on either individual drives or on a small RAID0 backed up to individual drives. (mainly because we don't NEED truly big and fast since we don't have humongous video or photo databases to wade through every day, nor does our network have enough users to need a big fast served storage system)

    The ONLY primary consideration in setting up a storage system is how we're planning to back it up. The secondary concern is how big and fast I want the primary to be - how big and how fast is where I just may decide to use a RAID5. My main reason for choosing the RAID5 will be that I can make it bigger, faster and with high quality controller and utility, I can ensure its uptime is best I can make it. A mature high end RAID system is the only way I can gain uptime by virtue of RAID5. Low end RAID5 is exactly the opposite effect on uptime as a problem will almost always take much more to fix, or even more likely be unfixable.

    I think you would be smart to go back to either a single big drive or a small RAID with an equivalent capacity backup. If you want speed, the primary as a RAID0, like a pair of 2TB drives, backed up to a 4 TB single drive is a good setup.

    Look forward to hearing back if Lycom answers We have great contacts there as well, work with their engineers on projects all the time. I would be interested in hearing about how they assist in your end user support request.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  6. #6
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    Rick,
    Thanks for the advice as well as the clarification of RAID5. I actually run a RAID5 on my QNAP NAS drive, and so far I've had good luck with it, so I'll probably stick with either hardware solutions or just simple backed-up drives as you suggested.

    I did get a final response from Lycom, and unfortunately the news is not good:

    The remaining RAID set is pink, indicating there were multiple errors which caused the RAID set unrecoverable. That is why the rebuild option is greyed out. If you check the log file, you should see some warning messages. When the RAID set starts deteriorating, ie. when some errors start to pop out, the RAID set would turn yellow. At which time, the RAID set is still workable and recoverable if the bad drive is identified and replaced. The "rebuild" option will be available from the drop down menu. When the color turns pink, the set already has too many errors, or multiple drives failure, and whole set would not be usable any more. The rebuild option would then be greyed out.

    I guess the only way I would have known about my steadily degrading disks was to run the Raid utility frequently. I had no idea this was necessary, but it appears that my ignorance cost me the drive.

    On a positive note, I was very impressed with the support I received from Lycom. After a few clarifying e-mails, they actually reproduced my setup completely (Mac, 4 drives, same card, etc.) and made a PDF of screenshots showing me how to rebuild the drive. That's more personalized support than I've ever received, so they should be commended. Unfortunately I wasn't able to follow their instructions due to the crapped-out disks, but I was gratified that they would take the time.

    Again thanks for all the help. I'll add this one to my ever-growing list of "lessons learned"!

    -Jeff

  7. #7
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    Last thing, when you rebuild the storage you want to rid yourself of the RAID5 drivers. 2 places and potentially several files need to be trashed: do this without the drives attached to the card.

    In /System/Library/Extensions take out all the SiliconImage3124.kext type files. Drop them right in teh trash.

    Next, in /Library/StartupItems drag out both SICoreServices folder if it is there, and most especially the RAID5Daemon.

    Then, download and install the proper driver for that card to run as a host card - non RAID. You can find it at the bottom of the card sales page.
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  8. #8
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    Nice that they did support you.

    And yes, without a timely notification, running a degraded RAID 5 is playing russian roulette. Better solutions have loud audio alarms, blinking lights, and automated email notifications.

    There is a reason for those...

    And the better solutions have a hot spare: an extra drive plugged in and waiting, that will automatically rebuild the RAID using the spare if something happens when you at happy hour.

    Then there is RAID 6 that can survive 2 simultaneous HD failures. The simple fact that RAID 6 exists and is fairly popular on high end storage should be a big clue to all of us that RAID 5 is not perfect. By a long shot.

    Having said all that....I have seen nearly zero catastrophic failures on good hardware that has been monitored and maintained...over the last dozen years. Have seen one or two low end consumer boxes appear to be scrambled for no apparent reason.
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

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