Question about ssd cache

[ruffpl 1]

I will be updating my xpenology server to DSM 6.1. I found on internet some cheap (used ) small 16 gb ssd drives ( something like this https://www.amazon.com/Apacer-16GB-180d-Module-8C-F1DD2-LR10B/dp/B00TP3JHJS). Does it worth to buy them and use it as ssd cache? Is it going to speed up acces to server files, download station, etc ( I have corei5 with 4gb ram and 8 hdds as a home server)?

Edited October 22, 2017 by ruffpl

[emkookmer 0]

You might want to read this kb artikel from synology

[ruffpl 1]

"To improve the random read and write performance of the storage space on which it is mounted." Does it means that it will be only cache for specified hdd, that I will choose ( for example disk selected for Download Station ), or to all disks that are in the server? I am thinkin about connecting 2x 16gb ssd in raid.

[emkookmer 0]

Quote

SSD cache can improve the performance of random access by storing frequently accessed data on the SSD cache.

 And as far as i know for all drives