Using NVME for appdata

[Megaman69]

So I just started with unraid, my parity build isn't even finished yet. I want to use my nvme drive for appdata for plex. yes, it may be overkill. Thats ok, I like overkill. I don't want this drive to be part of the array. Maybe I don't understand how unraid works. Anyway, is what I want possible? To keep the NVME seperate from the array and only use it for appdata? Or will I have to add it to the array, and change all shares not to use it?

 

Thanks

[itimpi]

This is a very common Use case.    You set your SSD to be the cache drive.   The commonest use for the cache drive is as an ‘application’ drive for when performance is important.    You can also use SSD’s as an Unassigned device if you do not want it to be part of the cache.

 

 

[trurl]

In fact, using an SSD in the parity array is NOT recommended. SSDs in the array can't be trimmed, their performance would be limited by parity, and there is a question of whether some SSD implementations could invalidate parity.

 

So put it in the cache pool.

[trurl]

Don't cache initial data load, cache just gets in the way. But do install cache before setting up dockers and VMs so they will go on cache where they belong. It is a bit of trouble to move them to cache later.

[Megaman69]

How do I do this? I cant figure it out. When I mount it with unassigned devices it doesnt show up in shares.

[trurl]

Unassigned Devices are not part of user shares.

 

We were talking about using it as a cache drive. You have to stop the array and assign it to a cache slot in Main - Cache Devices.

 

You will have to format it after adding it. If you think you might add additional cache devices then you have to format as btrfs.

[Megaman69]

Sorry, forgot to mention i already have a 2 tb ssd cache drive setup. I want to use the nvme for appdata only.

Edited December 1, 2019 by Megaman69

[Megaman69]

I got the NVME drive formatted and can find it from the cli, just not sure what to do now. do I just copy the entire appdata directory over, then change the docker settings to point to the new drive?

 

[trurl]

Something like that. I'm not entirely sure how things go with startup though since I haven't tried it. You would want it mounted before the docker service starts.

[Megaman69]

I am about to try cp /mnt/user/appdata /mnt/disks/NVME

 

Will that work to copy everything? I am asking because i have read about a copy bug, want to make sure i am not doing something stupid.

[trurl]

1 hour ago, Megaman69 said:

i have read about a copy bug

That only applies to mixing user shares with disks that are part of user shares. The problem arises because linux doesn't realize that the source and destination may be the same file, since user shares are just another view of the disks.

 

Unassigned Devices are not part of user shares, so that problem does not apply.

[Megaman69]

ok. thanks for the help.

[WayneC1972]

@Megaman69 Did you work this out? I am new to unraid, coming over from freenas. I want to do exactly what you have described. Did you get this to work? ie. 2 SSDs for cache and nvme for plex appdata only.