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I'm thinking of upgrading my NAS and was wondering your thoughts on SSD caching. Is it worth the trouble and an HD slot/volume for mostly video streaming? If so, how do I determine the size needed? I can have multiple Plex clients including a remote one streaming at the same time. Probably never more than three at a time though. I don't know if that really has any bearing on it though since I don't use the NAS as the PMS server. I'm pretty much self taught on networking and anything related so, I'm a bit confused on this one. Thanks for any advice.
 

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I'm thinking of upgrading my NAS and was wondering your thoughts on SSD caching. Is it worth the trouble and an HD slot/volume for mostly video streaming? If so, how do I determine the size needed? I can have multiple Plex clients including a remote one streaming at the same time. Probably never more than three at a time though. I don't know if that really has any bearing on it though since I don't use the NAS as the PMS server. I'm pretty much self taught on networking and anything related so, I'm a bit confused on this one. Thanks for any advice.
There's absolutely no need for SSD caching with streaming for a few reasons. The main one is that ssd caching algorithms typically allow large sequential reads and writes to bypass the cache completely.
 

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I'm thinking of upgrading my NAS and was wondering your thoughts on SSD caching. Is it worth the trouble and an HD slot/volume for mostly video streaming? If so, how do I determine the size needed? I can have multiple Plex clients including a remote one streaming at the same time. Probably never more than three at a time though. I don't know if that really has any bearing on it though since I don't use the NAS as the PMS server. I'm pretty much self taught on networking and anything related so, I'm a bit confused on this one. Thanks for any advice.
I agree with Rob, unless you are doing a very large amounts of reads / writes your bottleneck is going to be your network connection (assuming you have a fast NAS like a Synology) and if you have a slow one an SSD isn't going to make it much better.

Only if you have a bunch of systems accessing the NAS at the same time reading many different files that either don't change much on the NAS or change a lot to be written to the NAS are you going to see any benefit.

I personally wouldn't sacrifice the drive bay as I would keep it open for an additional hard drive.
 

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I setup a 16 bay supermicro Freenas (ZFS) with 2 pools (around 30Tb in total). I am currently using raidz3 and thinking of downgrading to raidz2 which would free up at least one caddy, which I could use L2ARC caching with ZFS supported SSD. I tried it on my Mac Pro running openzfs and found the streaming didn't really use the SSD cache. Here is the quote from the ZFS tuning guide : "By default the L2ARC does not attempt to cache streaming/sequential workloads, on the assumption that the combined throughput of your pool disks exceeds the throughput of the L2ARC devices, and therefore, this workload is best left for the pool disks to serve." As rottegift says on the openzfs for mac os x site, SSD l2arc is best left to accellerate random IOPS, not sequential (streaming) workloads. There is a way on Solaris to override this default, it may not be a good idea. using a SSD L2ARC also increases RAM consumption, so beware.
 
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