Caching SSD on Invisible Memory PLUS caching HDDs on SSD?

[uglyrooster]

Does it make sense to use the invisible memory for L2 cache of SSD AND to cache HDDs in L2 to this SSD?

It is working fine so far...

[dustyny]

It will work but you're adding latency, you're flushing data out of ram and then right back in.

I'd suggest that you assign the HDDs the largest lvl 1 cache you wish to dedicate and don't use more then 60-75% of the SSD as a lvl 2 cache (SSDs slow down as they fill up).