Adding SSD cache drives to a NAS, how much and is it a good or bad idea?

[GoogalyMoogaly]

So I'm debating adding some SDD cache drives to my NAS (TerraMaster F4-424).
I guess the first question is, is this a good thing or is it just a gimmick and a waste of time and money? SSDs aren't cheap so is there really much benefit to this?
I'm planning on upgrading my network to 2.5G (once I can decide on the switches to get) but even then it won't be close to the sustained read/write speeds of SSDs, so will it add anything?

Secondly, if the answer to the above question is that it is worth it, how much cache should I add and is there any benefit to using 2 drives vs 1 drive (twice the size)?
Is there a formula or something that says you want X GB of cache per TB of storage or something like that?

I'm not sure if NAS stuff is covered in here or the network sub-forum so sorry if this is in the wrong place...

 

[GoogalyMoogaly]

I have a spare NVMe drive in my DS920 for hosting virtual machines and the likes, it has immensely quietened down the HDD noises through the day.

The question of if it's worth it is very dependent on what you do. For example with Synology units having one NVMe (without forcing it to behaving like a normal drive) would mean it caches the most used files to speed up access to those files and the more storage you give it the more files it can do that for. Placing a second NVMe allows it to use the drives as a write buffer and that massively speeds up transfers.

If one of the 2 drives subsequently dies then it reverts back to a read accelerator configuration until a new second drive gets popped in.


I would say it's worth it if you are trying to quieten down the NAS for background tasks like I did or if you are trying make your transfer tasks quicker for your other devices (you will still see activity for about the same length of time on the NAS though whilst it moves data in to the discs).

You can work out roughly how much quicker than direct to the HDD's it would be but we need to understand if there is any RAID configured (and what RAID type that is) as that would determine the achievable throughput.

Edit: spelling as usual...

I'm not entirely sure what I want to use it for, I mostly use the NAS as backup and as a media server, but thinking of maybe also using it as a shared network drive to use across multiple PCs to put downloads and video editing stuff on.
I've got it configured with using TerraMaster's TRAID, which I believe uses a combo of RAID5 and RAID1, but I may be wrong on that.

I'm not sure How a TerraMaster NAS handles the cache drives. I think with the newer operating system you can choose to have the OS installed on the SSDs, but not sure what else it allows.

 

[GoogalyMoogaly]

Thanks guys, lots of good info and lots to think about.

For a cache drive I assume you need something with high endurance, such as a WD Red SN700 SSD?

 

[GoogalyMoogaly]

Gonna bump my network to 2.5G so it's not the bottleneck first and will take things from there.

Also need to figure out how I'm going to use the NAS to know if I need the performance.