Yes it was spaceinvaderone, I get the cache but how do you work out the size of it and one or two drives and yes regarding the parity drive if I use a 4Tb for now I am able to change it to say an 8 Tb down the road ?
Thanks
The size of the cache is basically as big as you expect to write to it before it moves files off to the array (array = protected storage, i.e the parity disk/s and storage disks), and how much you want to keep on the cache.
Some shares are recommended to remain on the cache drive such as the appdata share to speed up the docker containers. These settings can be set on a share by share basis, here's a copy of the writing from unRAID:
No prohibits new files and subdirectories from being written onto the Cache disk/pool. Mover will take no action so any existing files for this share that are on the cache are left there.
Yes indicates that all new files and subdirectories should be written to the Cache disk/pool, provided enough free space exists on the Cache disk/pool. If there is insufficient space on the Cache disk/pool, then new files and directories are created on the array. When the mover is invoked, files and subdirectories are transferred off the Cache disk/pool and onto the array.
Only indicates that all new files and subdirectories must be written to the Cache disk/pool. If there is insufficient free space on the Cache disk/pool, create operations will fail with out of space status. Mover will take no action so any existing files for this share that are on the array are left there.
Prefer indicates that all new files and subdirectories should be written to the Cache disk/pool, provided enough free space exists on the Cache disk/pool. If there is insufficient space on the Cache disk/pool, then new files and directories are created on the array. When the mover is invoked, files and subdirectories are transferred off the array and onto the Cache disk/pool.
NOTE: Mover will never move any files that are currently in use. This means if you want to move files associated with system services such as Docker or VMs then you need to disable these services while mover is running.
A cache drive size of 1TB is okay if you don't expect to write more than 1TB before the next mover run completes.
To your other question, yes you can change the parity drive later down the line. I think what you'd need to do is reset the config and keep the drive assignments. This will keep the drives in the correct positions they were assigned to. Then you can assign the newer drive into the parity drive pool and if you wanted, move the 4TB previous parity drive into the storage pool.
When you try to start the array it'll warn you that the new storage drive will be formatted and erased, and you'll also be told the array isn't protected as the parity drive is being rebuilt.
Basically it'll read all the data off your storage drives and create the parity data from it.
You can specify more than 1 parity drive if you want redundancy, all depends on how much protection you want.
Don't forget the licenses for unRAID have drive limitations, so you might not be able to use all the drives you want unless you have the right license.
