I created a share for all my media files and set it to cache "yes".  Then I started transferring all my media files from my other machine (3TB) to this share. What ended up happening is that the cache drive (500GB) ran out of space which caused a whole bunch of problems. My dockers, also on the cache, re-mounted in read only which seemed to corrupt all my dockers.

 

I’ve since had to manually run the mover to free up space and then disable/reenable docker and finally reinstall the dockers to get everything working again. 

 

My question is why is this happening?  I thought unRaid would automatically handle the out of space issue by transferring/saving files to the Array. Didn’t realize this could end up corrupting my dockers. 

 

Feels like I either don't understand how the cache works and/or have something configured incorrectly. Any ideas on what I'm doing wrong? Is there a way to prevent the cache drive from corrupting my dockers?

Possibly your docker.img was filled up due to misconfigured dockers storing data there. This can happen whether or not cache fills up.

 

When setting up a new system it is a good idea to take things slowly, get one thing working before adding more complexity. For example, finish your initial data load before installing apps.

 

Also, if you expect to copy a lot of data on a new system, it might be better to do so without cache, or even without parity.

You might take a look at Minimum Free setting for cache, and the mover schedule, for more insight into how best to use cache.

Thanks @trurl! I’ll check out the min cache setting. 

Note that Minimum Free, whether for cache or a User share, should be set larger than the largest file you will ever write. There is know way for it to know how large a file will become when it starts writing it. If there is less than Minimum Free remaining, it will choose to start writing on another drive. If there is more than Minimum Free remaining, it can choose to start the write on the drive, and if the file is too large, it will run out of space.