Swap cache device for array device?

[hayesg316]

Hi all - I am a new(er) user, and I am loving unraid. However, I am curious if it is possible to swap a cache device for an array device, and what the proceudre would be? I looked through the form, and I don't see anything that points me in the right direction.

 

My system has 6 disks, 4 3TB disks and 2 2TB disks. When I built the system, I mistakenly used a 3TB disk as cache, instead of one of the 2TB disks (making my array 1 TB smaller than I planned).

 

What I would LIKE to do is something like this:

 

1. Drop the 3TB cache drive completely (first mark all shares as no cache)

2. Offline one of the 2TB disks in the array.

3. Add the 3TB drive that was cache to the array to replace the 2TB one from step 2.

4. Do a parity check on the array (not sure if this is necessary)

5. Add the now "vacant" 2TB drive back as cache.

6. Profit?

 

Just not sure if this is the right procedure, and any potential issues with doing this? Is there an easier way? 

 

Thanks!!

 

EDIT: forgot to say one of the 3TB drives is a parity drive of course (sort of implied by the parity check comment, but figured better safe to have all the details) - Thanks!!

Edit Again: (New user, so can't post more... strange) - There is no data on the cache I can't live with out... so maybe step 0 would be "run mover to clear the cache drive"?

Edited November 14, 2019 by hayesg316

[trurl]

No that won't work.

 

Is there data on the current cache that you want to keep?

 

[hayesg316]

Now it lets me reply... strange...

There is no data on the cache I can't live with out... so maybe step 0 would be "run mover to clear the cache drive"?

[itimpi]

The following should work I think (it assumes you have a valid parity drive which you do not mention)

1. for all shares that have files on the cache set them to Use Cache = Yes
2. stop docker and VM services (if you have them enabled)
3. run the mover to move all files from cache to array.
4. if you are not sure if you have valid parity run a parity check
5. unassign the cache drive and the 2TB drive to be replaced
6. start the array to commit the new assignments
7. stop the array and assign the 3TB drive in place of the previous 2TB drive
8. restart the array to rebuild the contents of the old 2TB drive onto the 3TB drive.
9. stop the array
10. Assign the old 2TB drive as a cache drive
11. set any shares you want to end up on the cache to Use Cache = Prefer
12. run mover to move files from array to cache
13. restart docker and VM services (if you use them).

if you do not have a parity drive then the steps from 4 onwards will need revising slightly.

[hayesg316]

Perfect! That is pretty much what I was thinking, but your response is more detailed. I really appreciate it... Now just to find the time necessary to do the 2 parity checks! That will be like 4 days total on my system... 

Cool, thanks!!

[itimpi]

2 minutes ago, hayesg316 said:

Perfect! That is pretty much what I was thinking, but your response is more detailed. I really appreciate it... Now just to find the time necessary to do the 2 parity checks! That will be like 4 days total on my system... 

Cool, thanks!!

There is only 1 parity check in the steps I gave!   Where do you expect the second one to fit?

[trurl]

11 minutes ago, itimpi said:

There is only 1 parity check in the steps I gave!   Where do you expect the second one to fit?

And the 1 parity check (in step 4) is actually optional.

15 minutes ago, hayesg316 said:

That is pretty much what I was thinking

It is very different from what you posted.

 

If you aren't sure you understand please ask more questions. Or if you have any problems while following itimpi instructions, please come back for further advice.

 

 

DO NOT FORMAT any disk in the parity array.

[trurl]

31 minutes ago, hayesg316 said:

Now it lets me reply... strange...

Until I approved your new account, you were only allowed one post per day.

[hayesg316]

Thank you for approving the account, and yes, I see that your instructions are much more detailed. I understand the process - makes sense to me. 

 

I appreciate it a lot!