Using docker or otherwise, I notice that a lot of apps don't work if installed on the cache drive and insist on being installed to /mnt/disk1/appdata or the like. For small servers it doesn't make any sense to me to buy the unRAID plus licence. Instead shouldn't I just install all the apps to the array drive and forego the cache drive altogether? Obviously I understand the other shortcomings of a configuration of this sort, like drop in array performance during copying etc, but isn't it the same as the apps running from the array drive rather than from a non-array cache drive?

Using docker or otherwise, I notice that a lot of apps don't work if installed on the cache drive and insist on being installed to /mnt/disk1/appdata or the like. For small servers it doesn't make any sense to me to buy the unRAID plus licence. Instead shouldn't I just install all the apps to the array drive and forego the cache drive altogether? Obviously I understand the other shortcomings of a configuration of this sort, like drop in array performance during copying etc, but isn't it the same as the apps running from the array drive rather than from a non-array cache drive?

There should be no problem running from an array drive other than the performance hit of keeping the parity drive updated as you write to the array drive. 

 

You have to be careful when using a cache drive that you make sure any top level folders (that become automatic shares) are set to be cache-only but that should be the only 'gotcha'.

 

The other alternative to using a cache drive is to use one that is mounted outside the array and is thus independent of unRAID itself.  I have seen many who have elected to go down this route.  I have done this myself and added an entry to the 'go;' file to mount this extra device on system startup and then a complementary one to the 'stop' file (which needs creating if as is likely you do not have one) to unmounts properly on system shutdown.  A useful corollary of this approach is that this extra drive stays mounted regardless of whether the array is started or stopped.

 

What determines whether or not an app can be installed to the cache drive or not? Should this not be fixed? Its very annoying to have half your plugins on your cache drive and the other half on the array. I overlooked the aspect that parity will be written every time, lets say, plex transcodes a video or something. So what's the point of having docker in the first place since the array performance IS going to take a hit!?

What determines whether or not an app can be installed to the cache drive or not? Should this not be fixed? Its very annoying to have half your plugins on your cache drive and the other half on the array. I overlooked the aspect that parity will be written every time, lets say, plex transcodes a video or something. So what's the point of having docker in the first place since the array performance IS going to take a hit!?

There is NOTHING that mandates an app be installed on the cache drive - the choice is up to you!    The normal reason that this is done is to avoid referencing array drives unnecessarily and thus keeping the drives spun up.  However others like to always have all files on the parity protected area so are happy to take the performance hit.

 

Note that this does not mean that you cannot have apps installed on the array drive that reference paths on the array drives.  In the case you mention of plex transcoding a video that is on the array drives then you are going to have take the performance hit of reading that file from the array even if plex itself is installed on the cache drive.  There will be many apps that NEED access to the files on the array drive - and in such a case the paths mapped to a docker container will provide this access.  This will typically be done by providing access via /mnt/user when paaing folders to a docker container as this provides the combined view of the array and cache drives. 

 

Using docker or otherwise, I notice that a lot of apps don't work if installed on the cache drive and insist on being installed to /mnt/disk1/appdata or the like...

I've never had any problem with apps or dockers not working on the cache drive. Since they do work on cache, the rest of your questions are kind of moot.

 

Maybe you could provide more details about the problems you have encountered getting plugins or dockers to run on cache and we could address that.