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RAID 0 Partioning

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wholmes

macrumors newbie
Original poster
Aug 16, 2014
25
5
I have created a RAID 0 drive from two 4TB drives in High Sierra. When I go to partition the new RAID drive the partition button in Disk Utility is greyed out. Is it possible to partition a RAID 0 drive?
 
I seem to recall that RAIDs created in that way cannot be partitioned or contain a recovery OS or Boot Camp.
 
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I think you can do a RAID with an Apple RAID card, but those are only in the older Mac Pro and Xserver. What are you trying to accomplish?
 
Want to put a System Back partition for system SSD that has High Sierra on it on the RAID volume
 
System Back? Could you mean Time Machine? macOS does not support partitioning RAID drives like that. I may be incorrect, but I believe it cannot be done. You may be able to partition it when you create the RAID, but that is only a guess.
 
I do not use Time Machine. I use Super Duper. I want to put a backup copy on my RAID 0 disk if possible.
 
If you don't already have a bunch of data on the RAID 0 array then break it up into separate drives again. Then partition both drives exactly as you wish and identically. Then RAID those partitions:

For example, if you want a 120GB RAID 0 partition for your SSD clone - create a 60GB partition on each drive, with the remaining space as a single partition (unless you desire more partitions). Now create two (or more) RAID 0 sets, one of which is made of the 60GB partition of each drive, and the other RAID 0(s) are created from the remaining partition (or partitions).

I haven't really played with that much under High Sierra, but that was the way to do it under older versions of the OS IIRC...
 
wholmes said:
I do not use Time Machine. I use Super Duper. I want to put a backup copy on my RAID 0 disk if possible.
Click to expand...
That’s not safe. If either of your RAID 0 drives fails, you lose everything. It would be better to purchase a single drive large enough to back up everything.
 
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chabig said:
That’s not safe. If either of your RAID 0 drives fails, you lose everything. It would be better to purchase a single drive large enough to back up everything.
Click to expand...

This is a good point - don't rely on RAID 0 for your only backup. I routinely use RAID 0 for both primary storage and backups, but only because I also keep a redundant single-media backup. (Realistically, for your data to be truly safe, you need three copies; 1) your primary working copy, 2) a routine local backup and 3) an offsite backup. You'll also want to use at least 2 different backup methods, in case there turns out to be a bug or other issue. Yes, this does sometimes happen, for example (IIRC) it was Retrospect, a highly-respected piece of backup software that introduced a bug at some point that resulted in backups that could not be restored. And plenty of people have had enough problems with Time Machine I don't think anyone would recommend that as your only piece of backup software. So redundancy and multiple-methods are your keys to a robust backup solution.)
 
panjandrum said:
This is a good point - don't rely on RAID 0 for your only backup. I routinely use RAID 0 for both primary storage and backups, but only because I also keep a redundant single-media backup. (Realistically, for your data to be truly safe, you need three copies; 1) your primary working copy, 2) a routine local backup and 3) an offsite backup. You'll also want to use at least 2 different backup methods, in case there turns out to be a bug or other issue. Yes, this does sometimes happen, for example (IIRC) it was Retrospect, a highly-respected piece of backup software that introduced a bug at some point that resulted in backups that could not be restored. And plenty of people have had enough problems with Time Machine I don't think anyone would recommend that as your only piece of backup software. So redundancy and multiple-methods are your keys to a robust backup solution.)
Click to expand...

I agree. I use a similar backup strategy.
 
panjandrum said:
If you don't already have a bunch of data on the RAID 0 array then break it up into separate drives again. Then partition both drives exactly as you wish and identically. Then RAID those partitions:

For example, if you want a 120GB RAID 0 partition for your SSD clone - create a 60GB partition on each drive, with the remaining space as a single partition (unless you desire more partitions). Now create two (or more) RAID 0 sets, one of which is made of the 60GB partition of each drive, and the other RAID 0(s) are created from the remaining partition (or partitions).

I haven't really played with that much under High Sierra, but that was the way to do it under older versions of the OS IIRC...
Click to expand...

Agree, OP need to make partitions before RAID them together, but not RAID and then make partitions. The step does matter.

Since OP already has 2x 4TB HDD, so I expect he want some other partitions combination rather than 4+4. Also, it only make sense if OP want something larger than 4TB. Otherwise, partition a single drive is much better, especially for backup purpose.

e.g. If OP want 2+6, then he can partition each HDD into 1+3, then RAID the 1TB partitions together to get 2TB RAID 0 array, and the 3TB together to get a 6TB RAID 0 array. And once he done that, it can't be changed. Otherwise, almost required to backup all data, and then start from scratch again.
 
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