How can I temporarily remove a RAID set but keep the data?

Question

Level 1

1 points

How can I temporarily remove a RAID set but keep the data?

I recently had to restore my Netgear ReadyNAS to factory settings, which meant that I needed to make a backup of its data and restore it afterwards. The only possible way to back up the 8.5Tb of data was to get 9Tb of WD Red disks and somehow use them - so my immediate thought was that the Mac Pro would be a good idea. I t had four drives in it, but three of them were not being used by the OS so they could be temporarily removed.

So I replaced three of my four Mac Pro drives with new 3Tb drives and used Disk Utility to set them up as a JBOD. I then used this JBOD drive to back up the NAS and restore it again after I had re-installed its O/S (the whole thing took two weeks!!!).

So now I'm in the following situation:

* I want to tear down the JBOD set and take the three new drives out of the Mac Pro again and replace them with the drives I normally use there so that I can go back to making music (which is what I usually use it for).

* I also want to be able to put the new drives back in and read the data as a JBOD again if needed (in case anything is discovered to be amiss with my ReadyNAS backup/restore operation) - let's say for the next month I'll plan to keep the old drives around for safety.

How can I remove the JBOD set in such a way that I can set it up again using the same drives, and access the data (i.e. I don't want to delete the RAID set the usual way because that will delete the data too - apparently...)?

Posted on Sep 16, 2013 10:35 AM

Reply

Answer 1

Best reply

ds store

Level 7

30,705 points

Sep 16, 2013 8:27 PM in response to macronencer

Going to ask the mods to move this to MacPro, Hatter can answer your question, but I'm pretty sure if you power down and remove the RAID drives, you can put them in back again and boot up and the RAID will still be recognized as the info is stored on the drives themselves in the GUID/MBR of each drive in the set.

Also you should know, there is a new MacPro coming and it doesn't accept internal drives, only external.

So you should prepare and have some sort of external hardware redundancy for your data that isn't dependent on the Mac HFS+ formatting as Windows doesn't read that.

Perhaps exFAT would be better as both platforms can read/write that, but if the drives are going to be used with a PC ever, they need to be formatted by Windows for exFAT to get it right. Check first before you commit to copying huge data over.

Anyway research it, because if your MacPro dies, you might be up the creek and have some issues getting at all that data since it's in a RAID, external options might not work correctly or reliably for RAID.

Also consider talking to the fellows at MacGuru's, they are external RAID box setup experts for Mac's, sounds like you need a RAID 5 box, gives redundancy and can connect to any computer.

Hardware RAID is more reliable than software ones, cross platform as well.

good luck. 🙂

Reply

Answer 2

The hatter

Level 9

60,980 points

Sep 17, 2013 6:11 AM in response to macronencer

WD RED are fine for NAS, not fine for internal drive bays, find a NAS box.

Also I assume that Netgear is doing its RAID with its own proprietary bridge, not software using Apple DU.

Normally you can move software style arrays and they will be recognized, even if not in the same drive bay order.

For arrays, while you might be able to use WD Green, using those in any array is not good idea.

If you can get the data to fit then a couple (2) WD Black 4TB is fine. (But not using 10.8.4, and I don't know that I have heard if 10.8.5 has fixed the bugs in Disk Utility in 10.8.4 with drives larger than 2.2TB).

Reply

Answer 3

macronencer Author

Level 1

1 points

Sep 17, 2013 10:44 AM in response to ds store

Thanks for your help! I understand about securing data using redundant hardware in the future, but I'm solving a short-term problem at the moment.

So you're saying that I can simply remove the drives from the Mac Pro, replace them with the original drives, and it will start up as if nothing had ever changed? That's good news. I was only wondering whether I needed to remove the NAS group in Disk Utility first, so that it didn't get confused when it found the 'wrong' drives in place... I actually can't see a way to remove the JBOD group at all in DU. Is this perhaps because it is 'brought into existence' by the presence of the constituent volumes in the bays, and will therefore disappear when these are absent?

Reply

Answer 4

macronencer Author

Level 1

1 points

Sep 17, 2013 10:46 AM in response to The hatter

The hatter -

I may have been unclear about this, but it's not my intention to use the drives on a permanent basis. Regarding wanting to access the data later on, that was just short-term, and just for emergencies.

Eventually I plan to reformat all three of those drives. I was going to use two of them in the ReadyNAS to expand the size, but I was planning to use the third one to replace an existing WD Black 2Tb in the Mac Pro (my projects drive). Is there anything specifically bad about using a WD Red in a normal drive bay?? What could go wrong?

Reply

Answer 5

macronencer Author

Level 1

1 points

Sep 17, 2013 10:48 AM in response to macronencer

Addendum - having re-read both of your replies, it looks as if you have BOTH misunderstood me... I am NOT planning to use the Mac Pro as a RAID on any kind of permanent basis. It was simply a temporary host for a 3-disk JBOD. I used this JBOD volume to back up data from my ReadyNAS, then later restore it to the ReadyNAS.

I hope that helps clarify!

Reply

Answer 6

The hatter

Level 9

60,980 points

Sep 17, 2013 11:33 AM in response to macronencer

And you cannot even temporarily use WD REDs.

Buy a pair of 4TB something else instead.

Your Netgear unit uses its own RAID bridge.

Not something you have inside, is in addition to the "RED drives not working in Mac Pro" that I see posted more than once, and no one saying REDs work.

Redundancy and backup in your case is a SECOND NAS box.

Reply

Answer 7

macronencer Author

Level 1

1 points

Sep 17, 2013 1:10 PM in response to The hatter

OK, this is getting a bit confusing... let's back up and start again here!

"And you cannot even temporarily use WD REDs."

Yes, I can, because I already have. I have already installed the JBOD array in the Mac Pro, backed up the ReadyNAS to it, wiped and did a factory reset (on the ReadyNAS), successfully restored the data again, and it worked just fine. Or did you mean that it was just risky to use them?

I don't get why the Netgear unit's RAID bridge has anything to do with this. At no point did I say that I wanted to be able to take the drives out of one RAID on the Mac and use them in the Netgear unit to recover the data, if that's what you were assuming. That is not my intention. I would never expect anything like that to work.

My main question was: what do I do next, to ensure that my Mac Pro is happy when I swap my original drives back into it? I just thought that the 'JBOD volume' I set up in Disk Utility might have the potential to cause confusion when I do that, given that the drives will be back to the normal ones. I think ds_store has pretty much answered this, although I just wanted to be sure about the answer.

I will definitely check out the issue you mention with WD REDs though, since I was planning to use one in the Mac Pro, but if I can't do that for some reason, then that's fine - I'll keep it as a spare drive for the ReadyNAS instead...

Reply

Answer 8

macronencer Author

Level 1

1 points

Sep 17, 2013 3:27 PM in response to macronencer

Well, I took the disks out and everything is fine. I think I get it now: the RAID set appears 'magically' when its drives are inserted, and it does this because its configuration is stored on the drives themselves.

That's clever 🙂

Reply

Answer 9

macronencer Author

Level 1

1 points

Sep 17, 2013 3:32 PM in response to macronencer

Oh, that's a bit annoying... it seems I can't award 'solved' points for a post once I've awarded 'this helped me' points. Sorry about that, ds_store...

Reply