alt Hacker NewsQ - assuming the NAS was strictly used as NAS and not as a server with VMs, is there a point in having a large amount of RAM? (large as in >8GB)
I'm not sure what the benefit would be since all it's doing is moving information from the drives over to the network.
Replies
It depends on your file workload. The RAM can be used as a read cache.
I have some workloads where I have to go through a lot of files multiple times and the extra RAM cache makes a huge difference. You can tell when the NAS is pulling from cache or when it has a cache miss.
ZFS uses a large amount of ram, i think the old rule of thumb was 1GB ram per 1TB of storage
People get carried away with their home lab setups. There's a distinct type of person that thinks they need 100tb of storage in their own house.
If you're running a NAS for a company that has many users and multi disc access at the same time, sure. But then you're probably then not buying hdds to shuck and cheap components off ebay.
If you use ZFS you might need more RAM for performance?
Caching files in ram means they can be moved to the network faster - right?
ZFS cache.
As the other said already if you have more RAM you can have more cache.
Honestly it's not that needed but if you would really use the 10Gbit+ networking then 1 second is ~125Mbytes. So depending on your usage you can never even more than 15% utilization or have it almost all if you constantly running something on it ie torrents or using it a SAN/NAS for VM on some other machine.
But for a rare occasional home usage nor 32Gb nor this monstrosity and complexity doesn't make sense - just buy some 1-2 bay Synology and forget about it.
I am not at all an expert, I can only share my anecdotal unscientific observations!
I'm running a TrueNAS box with 3x cheap shucked Seagate drives.*
The TrueNAS box has 48GB RAM, is using ZFS and is sharing the drives as a Time Machine destination to a couple of Macs in my office.
I can un-confidently say that it feels like the fastest TM device I've ever used!
TrueNAS with ZFS feels faster than Open Media Vault(OMV) did on the same hardware.
I originally setup OMV on this old gaming PC, as OMV is easy. OMV was reliable, but felt slow compared to how I remembered TrueNAS and ZFS feeling the last time I setup a NAS.
So I scrubbed OMV and installed TrueNAS, and purely based on seat-of-pants metrics, ZFS felt faster.
And I can confirm that it soaks up most of the 48GB of RAM!
TrueNAS reports ZFS Cache currently at 36.4 GiB.
I dont know why or how it works, and it's only a Time Machine destination, but there we are those are my metrics and that's what I know LOL
* I don't recommend this. They seem unreliable and report errors all the time. But it's just what I had sitting around :-) I'd hoped by now to be able to afford to stick 3x 4TB/8TB SSDs of some sort in the case, but prices are tracking up on SSDs...