Hi All.

 

I am looking at swapping my mechanical cache drive to an SSD based cache drive. Unless I am mistaken there seems to be little to no documentation on how to move to a new cache drive, either an upgrade or a replacement.

 

Also there doesn't seem to be much in the way of what happens if you have a cache drive and you add an additional one to create a cache pool. Do all drives get wiped or does it just setup with pre-existing data? Hoping LimeTech can do something on this when they get a chance.

For upgrading/replacing a cache you can see this post from the other day - http://lime-technology.com/forum/index.php?topic=45024

 

From what i've read on other posts, when the second cache device is added a balance will be initiated on array start.  Alternatively you can start a balance from the WebUI.  When i created my cache pool i started with two empty SSDs as my old cache was an old spare HDD. I copied all the data from the spare HDD to the array so that i had a backup. I created the pool, manually initiated a balance from the webgui, and copied the cache drive contents back over to the pool without any issues.

If you start with a single cache drive but intend to move to a cache pool later then make sure btrfs is selected as the format as otherwise the upgrade process will wipe the existing contents when the format is changed to btrfs to support pooling.

To replace the cache drive just stop anything using it,  plugins, docker etc.  Copy the contents to an array drive, install the new drive and copy everything back.

 

Having spent the last two weeks using a cache pool and having nothing but problems and not finding much help for recovering btrfs filesystems I've gone back to XFS myself.