Originally, I had just one 256GB cache. At some point I added another 500GB, and everything automagically got copied over from the original cache drive, to form a mirror. Now, I have installed another 500GB SSD, and want to replace the 256GB drive. (So "Cache" will be the new 500GB, "Cache 2" is the old 500GB, they will still mirror each other).

 

With the array stopped, I selected my new 500GB drive as "Cache" (replacing the existing 256GB), and assumed all data would be automatically copied over from my existing 500GB "Cache 2" drive. But when I started the array, both cache drives had the status "Unmountable: Too many missing/misplaced devices".

 

I've changed back to the original setup, and I still have all my data mirrored on the old drives. So the question is, what is the proper procedure to replace "Cache" 256GB with new 500GB drive?

 

 

(I'd like to just mention another curiosity, after I got the "Unmountable" warning, I changed the selected "Cache" drive from my new 500GB, back to 256GB, and I got a warning saying all data on 256GB would be overwritten. But when I changed selected "Cache" drive to "no drive", then back to 256GB, the warning disappeared, and no data was overwritten. The fact that I first got this warning, then it disappeared sounds like a tiny bug perhaps? I had the old 500GB selected as "Cache 2" all the time while doing this.)

Edited November 28, 20214 yr by Ademar

20 hours ago, Ademar said:

ith the array stopped, I selected my new 500GB drive as "Cache" (replacing the existing 256GB), and assumed all data would be automatically copied over from my existing 500GB "Cache 2" drive. But when I started the array, both cache drives had the status "Unmountable: Too many missing/misplaced devices".

Pool device replacement is broken on v6.9+

 

 

If you're comfortable using the console you can do it manually.

Thanks for the tip, I ended up temporary moving all the data to the array, and building the cache from scratch.