Replacing Multiple Data Drives with a Single Larger Drive (Faster Method)

[bdcmrt07]

Hi friends, 

 

I am upgrading my Unraid server hardware and would like to replace multiple smaller disks with larger disks. I wanted some clarification on the official  instructions for this procedure (faster method) - https://docs.unraid.net/legacy/FAQ/replacing-multiple-data-drives/

 

The example used in the documentation does say "Either of these methods can be easily adapted to replace 3 or more drives with a larger drive." In my current configuration i have 5 data disks which i would like to replace with 2 18TB disks. 

 

1) The commands provided in the instruction are as follows: 

rsync -avX /mnt/disk1/ /mnt/disk3
rsync -avX /mnt/disk2/ /mnt/disk3

 

Question - Are these multiple commands entered all at once? Or do I complete the first rsync between disk1-disk3 wait for it to finish then enter the second rsync command between disk2-3? 

 

2) If multiple syncs at the same time are possible can I do the entire replacement to 2 new larger disks all at once using the following commands:

 

rsync -avX /mnt/disk1/ /mnt/disk6
rsync -avX /mnt/disk2/ /mnt/disk6

rsync -avX /mnt/disk3/ /mnt/disk6
rsync -avX /mnt/disk4/ /mnt/disk7

rsync -avX /mnt/disk5/ /mnt/disk7

 

Thanks!
 

[itimpi]

First I should point out that you are looking at legacy documentation.   It is not necessarily wrong but you need to treat it with caution.

 

In terms of running the commands you never want more than one instance referring to the same drives (either as source or target).   The reason is that if you do this it will typically be slower than running the commands one a time as you start causing excessive head movements on any drive referenced in more than one command.   If you have a parity drive this effect can be even more marked as even when the command do not reference the same drives you can get contention on the parity drive.

[bdcmrt07]

Thanks @itimpi for calling that out on the legacy documentation and appreciate the direction on the commands. I looked around but haven't found an updated version of that Faster procedure.  I have a parity disk (18TB) currently installed but I wanted to avoid doing multiple rebuilds replacing one disk at a time so was hoping to use the faster method.  I'll use one command at a time (or 2 referencing different source/target) to avoid the excessive head movements and the slowness that will come with it. Many thanks again!

Edited June 29 by bdcmrt07