I currently have an array of 15 disks, which I would like to extend by one more disk to make it 16. I checked the tutorial, but did not find anything related to Unraid 6 whether this is possible and how. The easiest may well be to recreate the array from scratch. Any other / safer way to do it? Thanks in advance!

I currently have an array of 15 disks, which I would like to extend by one more disk to make it 16. I checked the tutorial, but did not find anything related to Unraid 6 whether this is possible and how. The easiest may well be to recreate the array from scratch. Any other / safer way to do it? Thanks in advance!

In principle you can simply add it!

 

The thing to watch out for is that if you do the simple case then unRAID will take the array offline while it "clears" the disk to avoid the new disk affecting parity (assuming you have a parity disk), and this can take hours for a new disk.  If instead you use the Preclear plugin to carry out the "Clear" action before adding it to the array, then the array downtime is only seconds (even though the pre-clear process can take hours) as unRAID will recognise the "clear" signature that the plugin puts on the disk at the end of its processing.  The preclear process also has the advantage of carrying out a thorough confidence check on the drive which is a good idea on a new disk before trusting it with your data.

Thanks. Let me understand this step-by-step for Unraid 6:

 

1) Need to unplug the SD card fro my Unraid to manually copy preclear_disk.sh to the flash folder [nb: folder location varies in the two referenced threads)

 

2) Install preclear plugin from the UI in Unraid

 

3) Mount the new 16th disk, format it, preclear it

 

4) Stop the array

 

5) Change number of array disks from 15 to 16; add the precleared disk as 16th device

 

6) Start the array. All done

 

 

Sounds right?

1 - just make the USB smb / network read/write for a few moments and copy over your network

2 - yes

3 - do not mount the disk for then you'll not be able to clear it.  I suggest 3 preclears to get over bathtub failure rates

 

Yes to rest

Thanks for the quick reply:

 

re 1 - this will be the "\\my-IP\flash\config\plugins\preclear.disk" directory?

Thanks for the quick reply:

 

re 1 - this will be the "\\my-IP\flash\config\plugins\preclear.disk" directory?

Yes.  The USB Stick is referenced as /boot if you are doing it from the Linux level inside unRAID and as the 'flash' share if doing it over the network.

Thanks. Let me understand this step-by-step for Unraid 6:

 

3) Mount the new 16th disk, format it, preclear it

 

 

Sounds right?

 

Linux will assign the disk a sata device location, but it won't be "mounted" or formatted yet. Unraid will format it when you assign it as your 16th disk and start your array.

 

So connect the drive, boot Linux, do not assign this disk to the array yet, preclear the disk, stop your array, assign this disk to the array as your 16th disk then start your array (and a few moments later, after it's formatted) it'll be up and running.

Thanks both. The drive is actually already formatted. Assume this is not an issue? I just follow the process and it will do its trick?

Thanks both. The drive is actually already formatted. Assume this is not an issue? I just follow the process and it will do its trick?

 

It's not an issue, but it will be erased by pre-clear and reformatted, if that's an issue.

Thanks for your help. The pre-clearing (3 cycles) is taking several days. the time eater appears to be the step called "post-read". Is this normal for a 4TB disk? It is not finished yet, but assume it will in the end have taken a full week to complete all three cycles.

Thanks for your help. The pre-clearing (3 cycles) is taking several days. the time eater appears to be the step called "post-read". Is this normal for a 4TB disk? It is not finished yet, but assume it will in the end have taken a full week to complete all three cycles.

 

This is totally normal. My last pre-clear for a single 3TB drive was I think ~29 hours per drive, per cycle... so ~ 3 1/2 days. A 2TB drive I did last week took ~ 16 hours per cycle. I imagine each cycle for your 4TB will take around 40 hours or so?? Total guess as I only have 3TB drives.

 

As mentioned before, your array should be up and fully operational while this pre-clear process is getting your new disk ready.

 

Due to the time it takes to pre-clear, I generally will buy one drive more than I need in my system and pre-clear it so I am immediately ready for a data rebuild in the event of a disk failure. You don't want to rebuild on a (brand new) non-pre-clear'd disk and also you don't want to sit vulnerable while you take a week to pre-clear your replacement disk.