Let me help you with this.
Since you have a SSD (bootable) it is not necessary to cache the Operating System because the 250GB SSD is already running faster. However, you can accelerate the RAID with another SSD.
"However, you can accelerate the RAID with another SSD." How might I do that? And what size would be adequate? Would I still be using the Rapid Storage Utility?
If you have the Raid configured with mechanical HDDs you can accelerated by using the Intel® Rapid Storage Technology. It is also necessary to have an SSD of 18GB or more plus other components which I guess you already have since you have the RAID already setup.
Here you can find the acceleration guide for your system:
Hope It helps!
Kevin, thanks for your reply.
I wasn't sure if having the large (by the standards when Rapid Store Technology was written) SSD boot drive didn't achieve the same result that Rapid Store Technology was directed at solving. I do intend to also keep all commonly used applications on the SSD. The Raid 5 stack will be used for backup and data. Not knowing the innards of Rapid Store Technology, I didn't want worse at the expense of good performance by having a second dedicated (i.e., caching) SSD.
Pls reply one last time and I'll mark your response as the correct answer.
The SSD is much faster than a mechanical drive so having the Operating System installed in the SSD will definitely make the difference when talking about performance but you can also accelerate the RAID with another SSD (not the same as the bootable). This of course, will depend on your need so if you think you need faster data transfer on the RAID Volume another SSD will be needed.