Hi ... i know this is a kinda 'how long is a piece of string question' but i'm looking to invest in a ssd to be installed as a cache drive.  Question is how small is too small and how big is too big? It'll be used for a handful of dockers, Plex (possibly??) and a handful of vms. So what size(ish) should i be looking to install as a decent startup? Guess the real question is how large are you're SSDs?

Mine is a cache pool with total space of 250 GB.

 

I'm only running Plex, Transmission, and no VM's, or other Dockers. I also don't do a ton of writes to my array and when I do a write it's usually under 50-75GB of video files at a time.

 

The questions you should ask yourself is A) How often and how much data do I write intended to write to the array at a time (including things that pull data from the internet and write data for you)

 

B) How much space do I need for VM's and Dockers? (Someone else might be able to help with this.)

Thanks for that. I can write about 100GB two or three times weekly to the array so guess my starting size is around the 160GB mark + dockers + a couple of vms. Will 250GB do it or should i be going higher?

 

I've used 120GB SSDs that I had laying around for each of my servers, they both are fine. If you ever do start to copy more than they can fit to the array unRAID just starts writing directly to the array.

I have 2 x 120GB SSDs in btrfs raid1 cache so I get redundant storage with a total of only 120GB. I have never had it more than half full. I don't cache any user share writes. Only my docker's appdata lives there.

 

So it depends entirely on how you intend to use it and what works for me may not work for you.

My writes are via user shares which i think i would want to write to cache drive then move overnight to speed things up. Is it worth pooling a couple of drives to protect these writes and any docker/vms resident? Guess it comes down to the size of these as well. Anyone got any way to calculate the size of individual dockers?