Request: More advanced Cache Drive function

[Helmonder]

The current cache drive can be configured per user share. The cache drive can be turned ON and OFF per user share. Also the cache drive is emptied every hour, day, week or month.

 

This is a usefull the moment the amount of data you write is quite consistent, that way you can figure out how large your cache drive needs to be, to be able to live thru an hour, day, week or month.

 

In reality this amount of data is not that stable, this means that data can be kept on the cachedrive longer then it is held there because of the mover schedule.

 

This is correct behaviour since data on the cache drive is vulnerable to cache drive failure, the cache drive is mainly there to increate perceived write speed since data written to the cache drive is not part of the parity pool.

 

In V6 it is now possible to create a cache drive that is mirrored over more disks, this makes the cache drive at least as safe as the array itself, this makes it possible to think of the cache drive in another way (also: some users that do not have a mirrored cache drive might just not care if data on their cache drive is more vulnerable then in the array).

 

I propose to start thinking of the cache drive as a system to very quickly get access to your data. Most people use an SSD as cache drive so this is a realistic thought.

 

What if the cache drive would have a little more settings:

 

- Minimum free cache drive space

- Maxiumum time on the cache drive

 

This way the mover script could still run every hour/day/week/month, but it would only start moving stuff off the cache drive the moment it had less free room then the minimum free space, it would also stop copying stuff off the drive the moment that minimum free room would be reached. It would copy stuff off based on the written date of the file (oldest file gets moved off first).

 

Why ?

 

A lot of use the array for media storage,  in reality a lot of my personal viewing is watching my series and movies that I watch realitively soon after downloading. This way of using the cache drive would cause most of my media watched off the cache drive, and keeping the array spun down.