More than 2 cache disks?

[garethsnaim]

Hi, I have 2 evo ssds in use for cache, I believe they are mirrored. Thats fine but as I set the server up lots of copying to the riad is causing the cahce to fill up. I then note that the copy seems to do a bit then drop to zero, do a bit then drop to zero.

 

I could just turn off the cache I suppose but that got me thinking how would things behave if I had say 3 cache disks? Ideally I would be looking for another disk to be used for cache once the first one fills up, is this a thing?

[Frank1940]

I don't have a direct answer to your question but I do have a suggestion for you.  Google   unraid.net cache pool   and look  at the threads found.  I seem to recall that you can use an odd number of drives in a cache pool but I am not certain quite how to set it up. 

[garethsnaim]

Thanks Frank. I have taken a look around already but its a little unclear. I guess patience is key, I was just a little concerned today because I have a large copy to the array going on was always going to take a while but in the mean time plex docker came to a crawl taking minutes to load a tv show, presumably because it too is on the same cache. 

 

I am hoping beyond hope that unraid can serve my needs, I am not a heavy user but we can expect Roon and Plex to be in use at once at home and I would be gutted if the experience is compromised.

 

Coming from using ESXi, with a hardware raid in 0, so trying to managing my expectations!

 

The server is a beast so hopefully all will be good once all the copying stops.

[Arbadacarba]

Installing additional disks is pretty simple... Add disks, watch cache size increase.

 

It's still a raid though so it's not a 1 to 1 relationship. I had 3 1TB SSD's and got 1.5TB of storage. Basically you get 50% of what you put into it.

 

Is the project you are working on right now just the initial loading of the array? I ended up turning the cache off for the larger portion of that task.

 

Because the mover runs at night you will basically fill the cache and then switch over to the array. When the mover runs at night it clears the cache and the next day you have access to fast transfers again. That's Awesome for the daily workstation backups and for moving a few hundred GB at a time, but frustrating when you are pushing large volumes onto the array.

 

[garethsnaim]

Hi yes, in essence I am copying my back up of music/films etc to the array and appriciate that once the cahce is filled things rae going to drop off and thats indeed whats happened.

 

I am not moaning, just want to learn so much so quickly! Have been used to OMV or ESXi but can totally see the benefits of unraid, but equally the speed of raid is not something I want to land up missing.

 

i.e. copying my music library back to raid zero took around 8 hours but on unraid I estimate I can quadruple that time, but patience I guess is the key, particularly as I can see how dockers are very usefull.

 

All good learning stuff!

 

[Arbadacarba]

Dockers are great, but for your music collection you should see pretty good results. The read speed is as fast as a standard drive, so unless you have an incredible number of simultaneous streams (I think it is in the range of 500) you should see zero problems.

 

Movies can be a little more stressful especially if you are using 4k but I routinely run three streams off my unraid system.

[garethsnaim]

Thanks for the heads up. We will see.

 

So far I am a bit concerned, I set roon to importing the library last night and this morning its not even half way through. When I ran OMV on this same hardware in a vm it took little over an hour, I am not sure if this a docker issue or unraid, but unraid does not seem to utilise ram at all, not sure if thats the issue.

All the cores are being hit, which I want because I told roon to analyse the files on 20 cores, but over night it barely managed 3000 tracks, this is really bad, it should have been done and dusted in a few hours.

 

I will see how it performs once its eventually imported but so far a 10x decrease in performance might be a step to far!

Edited October 6, 2019 by garethsnaim

[garethsnaim]

Thinking about it whilst I have playing with unraid I set up roon in windows on a 4 core T310 and the library is on one 6tb disk and that took about an hour and a half to import. This is really not right.