RAM use and SSD cache - a Hindrance or boost for a home user?

[attxwill]

So I have a leftover NVMe M.2 drive sitting in a drawer because I replaced a 512 Western digital in my laptop with a Samsung 970 EVO plus 1TB.
In other words...its "free" and currently useless.

I am waiting for a 920+ to be delivered, with my use case Synology Photos, Family Files storage, Surveillance for 1 cam, and either Plex or Synology Video.

This said, I read enough to be dangerous on this since i had a ree drive so it raised a few questions from a simple home user perspective - should I install this SSD given these concerns:

• RAM versus CACHE: Since I only have 1 SSD drive, I know it will be "read only". And I understand RAM is always good for overall experience, and nvme will likely not boost my performance in my use scenario (at least i read so). AND Synology says SSD caches require a certain amount of system memory. The larger the allocated cache capacity, the more system memory is required. If RAM is really what is needed, then I question if this makes me worse off or better in terms of speed?
• WHAT SIZE? And if the cache option provides benefit here, shall I use the 512 GB or the 1 TB? Since I have a NAS now, I no longer need the 1TB size on my laptop, so I can swap the 512 MB back in and use the 1 TB in the NAS. But this would eat more memory to set up, and I have no idea how much would be utilized. Hence it raises similar benefit questions.
• Reliability and ease of use: While the cache is trying to improve the performance of my system, in theory it consequently decreases the reliability with additional points of failure, as its an extra hop for that data to pass through before it reaches its destination. With read only and my use case, is this even a real concern??

I am asking these based Please give me the knowledge knock to the side of the head i need around SSD caching.

 

[tomes]

Hi, did you ever get an answer to these questions? I'm looking at a similar use case.

 

[Jan Janowski]

Not super technical, but have a 718+ and a 720+, both with 6GB total memory, both with 2x 7200rpm 6TB Ironwolf’s in SHR, but 720 has had 2x 256Gb Ironwolf NVME’s and at another time had 2x 512Gb Samsung NVME’s……. And I was able to determine a slight speed difference improvement of 720+ over718+…. I did not see or feel a difference of 512Gb over 256Gb of NVME Cache on the 720+ In general home use.
The only reason I had tried a different cache is because I got a second 720+, and it was going to be stuffed with smaller Barracuda 7200 drives in SHR, and I wasn’t able to find 510 Ironwolf NVME’s, so I bought Samsung 512’s and put them in original 720+, and put 256Gb 510’sin new 720+ with smaller barracuda’s than the Ironwolf’s.

As an addendum to this, I see no speed difference with 2x 720+’s: One with 2x 6TB 7200 Ironwolf’s SHR, 6GB ram, & 512Gb Samsung NVME’s…… and other 720+ with 6GB ram, 2x 1TB 7200 Barracuda’s SHR, and 256 Ironwolf 510 NVME’s. Both act and feel the same from where I sit!

 

[Robbie]

I experimented with NVMe cache in different NASes and use-cases and, in all honesty, it makes more sense to invest in an SSD volume. RAM upgrades also make a lot of sense on units that will allow it as the RAM cache on DSM has improved considerably.

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