About SSD caching

[mobiuspizza]

Hi
I have a few question on the software

I have a couple of very old SSDs, 16Gb ones. Intel who just released new Z68 chipset and a SSD caching feature called Smart Response Technology, which will be available in the Intel Rapid Storage Technology 10.5 drivers.
I'd assume it performs the same thing as the 2nd level cache in your software?

Because Intel does not support drives less than 18.6GB, if I don't want to waste my old 16GB SSDs, I can use FancyCache.

However, that brings more question.

1. For mechanical HDDs, is it still benefitial, if the SSD isn't very fast in sequential speeds, say my old 16GB SSDs, to be used as 2nd level cache on top of RAM cache? Or is it better for me without?
2. If I have a very fast main 256GB SSD drive, can I enable 2nd level cache for my other mechanical HDDs only, since my 16Gb SSDs will slow the fast main SSD down.
Is there an option to have different caching for different drives?
3. Can I have read cache on the RAM and write cache on the SSD to prevent data loss on power loss?

Thanks

[Support]

Is there an option to have different caching for different drives?

Yes, you can specify different caching scheme for each drives.

3. Can I have read cache on the RAM and write cache on the SSD to prevent data loss on power loss?

No, it can't.

And please note that currently the level-2 caching data on the SSD doesn't persist after computer reboots.

[mobiuspizza]

Oh thanks
In that case I'd suggest to developers to consider using SSDs as persistent caches like the Intel's Smart Response Technology

Intel's SRT functions like an actual cache. Rather than caching individual files, Intel focuses on frequently accessed LBAs (logical block addresses). Read a block enough times or write to it enough times and those accesses will get pulled into the SSD cache until it's full. When full, the least recently used data gets evicted making room for new data.

Since SSDs use NAND flash, cache data is kept persistent between reboots and power cycles. Data won't leave the cache unless it gets forced out due to lack of space/use or you disable the cache altogether. A persistent cache is very important because it means that the performance of your system will hopefully match how you use it. If you run a handful of applications very frequently, the most frequently used areas of those applications should always be present in your SSD cache.