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vworks

macrumors regular
Original poster
Oct 21, 2017
153
16
Hi!
I am planning to make a raid 1 for my mother's mac pro 1,1.

She has 2x4 tb disks I just bought and I was thinking of the easiest way for her (she is not a tech person) to have kind of a back up on 2 disks. I first thought of CCC but even if I make a script, I fear she will do something wrong ...
Until now she used 2 disks copying manually to the both of them with some small differencies.
But I would like to set up the raid 1 config now and would like to know this -

How long does it take for a 4 TB disk to be rebuilt in the raid 1 if one is failing?

I am asking this because I tested this config with 2x250 gb disks and it took like 40 min to rebuild 2 files (500 megs)!!
So I am afraid that in case of failure this will take several days and this is not an option for me.
And I read on some forums that it really takes a lot of time to rebuild which is not very logical because it should just copy/paste the files unless the raid 1 is something really special and does take more time because of its 'architecture'....

Thank you!
ps. The disks are only data - no system on them.
 

jbarley

macrumors 601
Jul 1, 2006
4,023
1,895
Vancouver Island
CCC has excellent built in scheduling, I have my wife's laptop setup to daily clone to an external drive and weekly clone to a network drive.
This all happens automatically in the background without interfering with her workflow.
 

Draeconis

macrumors 6502a
May 6, 2008
987
281
Hi!
I am planning to make a raid 1 for my mother's mac pro 1,1.

She has 2x4 tb disks I just bought and I was thinking of the easiest way for her (she is not a tech person) to have kind of a back up on 2 disks. I first thought of CCC but even if I make a script, I fear she will do something wrong ...
Until now she used 2 disks copying manually to the both of them with some small differencies.
But I would like to set up the raid 1 config now and would like to know this -

How long does it take for a 4 TB disk to be rebuilt in the raid 1 if one is failing?

I am asking this because I tested this config with 2x250 gb disks and it took like 40 min to rebuild 2 files (500 megs)!!
So I am afraid that in case of failure this will take several days and this is not an option for me.
And I read on some forums that it really takes a lot of time to rebuild which is not very logical because it should just copy/paste the files unless the raid 1 is something really special and does take more time because of its 'architecture'....

Thank you!
ps. The disks are only data - no system on them.

RAID1 would exactly duplicate what’s on one disk to the other. But that includes mistaken deleted files, and file system corruption, which in HFS+, is possible.
 
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vworks

macrumors regular
Original poster
Oct 21, 2017
153
16
Well 500 mb taking 40 mins to copy is very long!
I think there is something else here.
But I will use CCC

ps. Nothing deleted after disk being formatted
 
Last edited:

Mikael H

macrumors 6502a
Sep 3, 2014
864
539
Well 500 mb taking 40 mins to copy is very long!
I think there is something else here.
But I will use CCC

ps. Nothing deleted after disk being formatted
A RAID1 rebuild will take at least the time it takes for the disks to transfer the amount of data stored on the old healthy drive to its new mirror, and possibly the time it takes to transfer each block of the old healthy drive to the fresh mirror, depending on the algorithm used by the RAID software. To cut down the time, use faster drives.

RAID mirrors are a good way of lowering the risk that a drive failure causes downtime, and may be a good idea if you live far away from your mother and can't help her with the computer immediately upon a drive malfunction.
RAID mirrors are not a good way of ensuring the safety of the data stored on the drives. I'll third @jbarley's and @Draeconis' posts: Make sure you have backups of your RAID sets.
 

vworks

macrumors regular
Original poster
Oct 21, 2017
153
16
Thank you!
That explains a bit more the 'problem'
 
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