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AndreeOnline

macrumors 6502a
Original poster
Aug 15, 2014
555
344
Zürich
Refresh my memory: If I have a set of two HDDs in a Raid 0 configuration in a 5.1 Mac Pro on Big Sur, can I move the set to a new 7.1 and expect Big Sur on the new Mac Pro to recognise the structure and configuration of the Raid set?

Thanks!
 

Syncretic

Contributor
Apr 22, 2019
265
1,084
I have a similar question for anyone who might know: I have multiple RAID-1 arrays on my MP3,1 and MP4.5,1; is it reasonable to assume that I can move a RAID-1 disk pair from one system to the other and have it work without issue? Is it likely to work in both directions (3,1->4.5,1 and 4.5,1->3,1)?

Thanks for any insights.
 

iliyan61

macrumors newbie
Mar 20, 2020
10
2
you cant just move RAID disks as the mac's software doesn't know what to do with them. Make sure you have a good copy of all your data on a 3rd drive just in case and then disband your RAID and redo it on the new mac. There are ways you could just move the array over but it's likely to fail and just bad practice even if it's quicker in initial setup you're risking losing all your data from a small error
 

Nguyen Duc Hieu

macrumors 68000
Jul 5, 2020
1,517
409
Ho Chi Minh City, Vietnam
Refresh my memory: If I have a set of two HDDs in a Raid 0 configuration in a 5.1 Mac Pro on Big Sur, can I move the set to a new 7.1 and expect Big Sur on the new Mac Pro to recognise the structure and configuration of the Raid set?

Thanks!

RAID is a complicated set-up. Even when you are moving the RAID disks to an exactly same other machine, the probability to keep the data is still not 100%.
Moving to a completely different machine will ensure data lost at 100%.
That's the reason why the most common advice you will receive is: back-up your data to external storage before changing anything of your RAID set-up.
 

h9826790

macrumors P6
Apr 3, 2014
15,393
7,671
Hong Kong
Refresh my memory: If I have a set of two HDDs in a Raid 0 configuration in a 5.1 Mac Pro on Big Sur, can I move the set to a new 7.1 and expect Big Sur on the new Mac Pro to recognise the structure and configuration of the Raid set?

Thanks!
You can just make a quick experiment.

1) Format a USB thumb drive on the 5,1

2) split that thumb drive into two partitions (e.g. for a 16GB thumb drive, make that 8+8)

3) RAID that two partitions inside disk utility in RAID 0

4) copy some files onto it

5) move that thumb drive to the 7,1 and see if the 7,1 can read the files

If you want a more accurate test, you can run this test with two thumb drives to simulate two hard drives.

If that works, it means you should able to transfer the RAID 0 array to the 7,1. Of course, no guarantee.
 

AndreeOnline

macrumors 6502a
Original poster
Aug 15, 2014
555
344
Zürich
Thanks to all for the replies.

My thinking was along the lines that when macOS creates a soft RAID set, it would be reasonable if each disk had something on it that said "I am physical disk aaa which is logical disk 1 of 2 in the RAID set XXX" and "I am physical disk bbb which is disk 2 of 2 in the logical RAID set XXX".

Any computer (and especially another Mac that reads the file system and understands the structure) would then just scan the headers and "rebuild" the set appropriately by relinking to the disks new physical position.

It seems strange to me that knowledge of the RAID set would be stored external to the disks. Seems inflexible and error prone.

In the end I'll most likely just make an in-between step and copy data to a large HDD and then back to RAIDed NVMes.
 
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