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Author Topic: Mac Raid question  (Read 1003 times)

tonysiciliano1

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Mac Raid question
« on: November 01, 2017, 12:15:38 PM »

I have two 6 TB disks (Lacie 2Big 1 Thunderbolt) on external drives that I use for photo storage. I back up the first drive onto the second using Super Duper. I need more space so I'm thinking of combining them into a concatenated drive of 12 TB and purchasing two more 6 TB drives and also combining them into a second concatenated 12 TB drive. Rather than use Super Duper to back up, I would like to mirror the two 12 TB drives. Will the current Mac Disk Utility do this, or do I need to buy a more robust Raid software program? If so, which program? Also, if I have all my photos on one concanated 12 Tb volume, to set up a mirrored raid would I have to erase that disk first?

Mac 10.12.6, will upgrade soon to Mac 10.13


« Last Edit: November 01, 2017, 12:32:12 PM by tonysiciliano1 »
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David S

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Re: Mac Raid question
« Reply #1 on: November 01, 2017, 12:30:35 PM »

You might want to try SoftRaid.

https://www.softraid.com/

Works well.

Dave S
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BobShaw

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Re: Mac Raid question
« Reply #2 on: November 01, 2017, 04:59:07 PM »

So if I understand this there are two drives of 6TB each in the same housing and you put data on one and back up to the other?

Well the first thing to realise is that you have no backup if both drives are in the same housing. They can both be taken out by the same event and there are many ways that can happen from power surges to housing software failures. Also one backup is literally next to nothing.

If the software allows it the best thing you can do is let the software create a 12TB drive from the two drives for your data and back up to multiple separate hard disks using Time Machine. Only one backup disk should be connected and powered at a time.

Obviously before you do that you make a backup of the data (and usually OS, apps, users etc) before you erase and recreate the array.
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Joe Towner

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Re: Mac Raid question
« Reply #3 on: November 13, 2017, 09:23:41 PM »

Why?  I mean, what are you trying to accomplish?  You need more space, what other backups are you doing?  How are the 6TB Lacie 2Bigs setup - are they a RAID0 of 2 3tb drives?  Are you looking for faster disk performance than what you currently have?

Here's a cleaner method.  Your current setup is 2 drives, with A sync'ing to B.  What I would do is stop adding to A, put B somewhere safe & offline and add a new set of disks, C & D.  Setup the same method you've been doing for A->B but for C & D.  So there are 3 drives online: archive, live & backup.  Archive has a mirror (B) that's tucked somewhere safe.  If the archive disk that's plugged in dies, you pull your backup copy out (B), purchase a new disk and mirror it to the new drive.

Only thing I would consider is if the 2Bigs are setup as RAID0 I'd snag 2 large (8tb) externals instead.  Use A as the archive, but copy B to 8tb(1), erase B & setup as the new Live disk.  Finally, setup the 8tb(2) as the receiver of sync's from B.  8tb(1) is tucked away safe at this time.  My intent is to consolidate your data onto single drives without any RAID.  I do not recommend spanning any mirroring or RAID between external enclosures - you're a bad power supply of having all your data inaccessible, or worse, corrupted.

Unless you really want to get into the IT side of things, RAID should always be contained in a single enclosure.  If you want to put a bit more into this, doing a multi-drive setup with https://eshop.macsales.com/shop/Thunderbolt/External-Drive/OWC/ThunderBay-4-RAID5 and disks is pretty straight forward.  The included copy of SoftRaid is pretty slick, but again, you're looking at a RAID5.  If you can deal with USB3, it's cheaper, but everything is a trade-off.

## Edit
So with the current setup 2x 6tb disks in the 2Big, I'd actually slightly adjust it 6tb1 is your new 'archive' - copy the second 6tb drive to an external 8tb, format the second 6tb as your new 'live' and setup a new 8tb external as the sync to.  If the enclosure or a drive in it dies, you have a copy of everything on other disks.

-Joe

« Last Edit: November 13, 2017, 09:30:13 PM by Joe Towner »
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David Eichler

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Re: Mac Raid question
« Reply #4 on: November 16, 2017, 04:02:19 PM »

The primary reasons to use RAID are either to increase speed with hard drives or to minimize downtime when a drive fails, or a combination of these. Secondarily, if you need to use a volume that is larger than any single drive can handle, you can combine drives in a RAID to accomodate that. If your only purpose is to increase storage capacity, then just buy more drives and keep backing them up with Super Duper or equivalent.
 
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