I have a macOS Server setup which is connected to two RAID (0, I think) systems. One of them does not work anymore.
Disk Utility shows that one drive is missing/damaged. It is not missing, thus it must be damaged.Disk Utility info

This RAID system was used for Backups, which we currently are doing somewhere else and therefore it is not necessary to get the data back, but welcome.

The drives are two Seagate Barracuda with 3000GB storage each. Taking the drives out of the case and plugging only one of them into the Mac produces the following behaviour: With both drives macOS shows this error prompt: Error Prompt (The inserted media could not be read from this computer; Initialize/Ignore/Eject)

  1. Powering up the drive makes a weird chirping noise. Initializing faulty drive shows up in disk utility, but apparently is 4.14GB big: Disk Utility of failed drive I can't use it (i.e. look at files on it) and it does not appear in Finder. After some time (maybe 10 minutes) the drive disconnects. Hitting eject and Ignore obviously doesn't do anything.
  2. Initializing working drive shows up in disk utility as well, but seems ok to me:Disk utility of working drive Similarly though, I can't use it (i.e. look at files on it) and it does not appear in Finder. It does not disconnect. Hitting eject and Ignore obviously doesn't do anything.

My question: What steps should I take next, to investigate this issue without harming the failed drive further?

  • I assume the drive failure is a hardware problem and it is gone and can't be used in future.
  • I hope, there is a possibility to recover the data.
  • I believe I can continue using the LaCie 2big enclosure with a new drive. Does this have to be a Seagate Barracuda 3TB or would something else work as well?

If you have read through all this: thank you so much!

  • If you're going to get new drives, stay away from Seagate. Decades in IT I saw first hand they are horrible, but I found an article that backed up my opinion: apple.stackexchange.com/a/314861/119271
    – Allan
    Feb 16, 2020 at 20:57
  • Ok very interesting.... I assume you are (as the mentioned post) recommending Western Digital Drives?
    – X_841
    Feb 16, 2020 at 20:59
  • Absolutely. I like HGST (Hitachi but formerly IBM) as my top, followed by WD and near the very bottom is Seagate. I've had WDs fail, but not at the rate that Seagates did. In a school with about 1000 kids with Seagates in laptops, we were running a 60% failure rate. I know that number because I had a meeting with Apple regional execs about it.
    – Allan
    Feb 16, 2020 at 21:02
  • Impressive. Seems like LaCie should not use those drives and Apple shouldn't recommend LaCie...
    – X_841
    Feb 16, 2020 at 21:13
  • Apple (and every other tech company) makes recs not on the tech actually being good/reliable, but what makes a good image.
    – Allan
    Feb 16, 2020 at 21:26

3 Answers 3


What steps should I take next, to investigate this issue without harming the failed drive further?

Stop using, manipulating, testing, whatever you're doing to the drive immediately.

At this point, all you know is that your RAID array failed. You don't know what in your RAID failed and it could be one of two components:

  • The enclosure
  • The drives

If it's the enclosure, your drives are likely fine. Continued use of them, even if interrogating them for diagnostics could compromise the RAID table sending your data into oblivion. You can test the enclosure by putting in two more drives; cheap, used ones are fine and they don't have to be large capacity as you're just testing functionality. If things fail again, it's the enclosure.

If it is the drive, you don't want to keep testing them out or attempting data recovery, you could further damage them making recovery impossible.

  • If the drives are somewhat operational and if possible, make a bit-for-bit clone of your drive to a file. You can use dd for this task and you will do it for each drive:

    $ sudo dd if=/dev/rdiskX of=/path/do/imagefileY.img

You will end up with two image files, one for each disk. rdiskX is the disk identifier of the disk you're copying. You can then write those images to good disks to attempt to reconstruct your array as many times as you want without the risk of further data loss.

  • If the drives are physically damaged, you may still be able to recover them by sending them out to a shop that specializes in this type of recovery. Many times, it's the PCB, the drive motor (the one that spins the platters) or the stepper motor (the one that moves the heads). This company will replace the broken components so that you (or them) will be able to extract the data.

RAID Recovery Software

You mentioned that you don't know what RAID Level you were using.

I have a macOS Server setup which is connected to two RAID (0, I think) systems.

This is not entirely critical. If the drives can be remounted, the RAID table which holds the configuration can be read and recovery can proceed. I have recovered RAID arrays in Windows several times using software made by Stellar Phoenix with excellent results. There are a couple of RAID recovery vendors for Mac, though I haven't used them (because I changed my backup strategy long ago) - take a look at Prosoft Engineering and Easus. I have heard (anecdotally) good things about each.

This brings us to the final point that needs mentioning...

RAID is not a backup!

RAID is for performance and/or redundancy, not for backups. RAID 0, is striping data across at least 2 drives meaning the two drives are "combined" to serve as one big drive and both drives working in tandem means you get twice the performance (two drives reading one file). RAID 1 is mirroring which is great for redundancy and uptime. If a drive fails you continue to function lessening the impact of downtime.

PC Magazine has an excellent write up on the different RAID levels.

Backup Strategy

Going back to what I said about changing my backup strategy a long time ago, I architect everything (in my server rooms) for redundancy. Multiple servers would connect to two mirrored disk arrays that was either RAID 5, RAID 10, or RAID 0+1. Then we had two backups - one that did a differential every day and another that imaged the whole array weekly.

This is overkill for your purposes, but it illustrates the point of not relying on RAID for your backups.

In your case, you can use your RAID enclosure for backup. However, I would also have a cheap USB drive (a second backup) that backed up your system as well. The chances of both failing are much smaller now. I've written several answers on backup strategies:

  • I don't have two spare drives which I could use for testing whether the enclosure is the issue or the drives itself. But isn't it more likely that the one drive has failed since the other one seems to be working which partly rules out the enclosure? I have BootCamp running so no issue with Windows software...
    – X_841
    Feb 16, 2020 at 21:10
  • I'm not sure what you mean by "one working." If they are striped (RAID-0) then neither should work. If mirrored, then that's possible. However, without putting eyes and hands on it, I hesitate to give a definite diagnosis. Now, when I say two cheap drives, used ones you find on Craigslist are sufficient to verify the enclosure (it's always good to keep some old parts around for testing).
    – Allan
    Feb 16, 2020 at 21:14
  • I connected each drive to my Computer on its own and one of them at least shows the correct specs and sounds normal (with a SATA to USB adapter) compared to the other one. Is there a way to verify that one drive is working without the other one? I'll have a look at cheap drives then, thx
    – X_841
    Feb 16, 2020 at 21:21
  • If you can do that...image it (as described in the answer) first to secure your data. It may have been mirrored, but I don't know. You can use Disk Drill on that image and attempt a recovery. I'd make a backup copy of the image, too, before doing any sort of manipulating the image.
    – Allan
    Feb 16, 2020 at 21:46
  • What do you mean by mirrored? If you mean RAID 1, I think no, since we were using 6TB which means the two 3TB were combined as RAID 0.
    – X_841
    Feb 16, 2020 at 21:49

If it's a striped RAID setup (e.g. RAID 0), then failure of one drive means you lose the whole thing. If one drive isn't working, you'll only have half of every file.

You should be able to install any pair of compatible drives, e.g. 3.5" SATA or whatever.

  • Is there a way to find out what RAID system was being used?
    – X_841
    Feb 16, 2020 at 18:01

Early in your question you mention that you think it was a RAID-0. It is very important to know what kind of RAID it was.

If it was a RAID-0 there is no parity, fault-tolerance or redundancy so if one of the drives failed, which your description suggests, and it truly was a RAID-0 then your data is gone.

It is possible that you can ship the drives off to a data recovery company and they may be able to recover some or all of the files on the drives, for a fee.

Really the only reason to use a RAID-0 is so you get increased throughput and disk/SSD write speed. If you are looking for a RAID as a safe and redundant way to store valuable data then you need to look at (at least) a RAID-1 (usually referred to as a "mirror") so that if one drive fails the other has the data on it or the data is stored in such a way that you can easily recover the data (such as RAID-5, 10, etc.).

So in summary if it is RAID-0 and the drive died your data is gone. Recovery will be expensive, if at all possible.

  • If I had the full 6TB available, then it must have been a RAID-0, right?
    – X_841
    Feb 16, 2020 at 18:14
  • @X_841, If you have two 3 TB disks in a RAID where 6 TB is available, then yes it's RAID-0. Feb 16, 2020 at 18:18
  • I highly assume that the behaviour means one drive is broken, right?
    – X_841
    Feb 16, 2020 at 18:22
  • A chirping drive is a dead drive.
    – IconDaemon
    Feb 16, 2020 at 19:26
  • Yeah that's what I assumed and it is definitely a different and bad sounding noise...
    – X_841
    Feb 16, 2020 at 20:59

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