This could be made in software with benefit, as a Softraid patch.
So the frequently accessed stuff ends up cached on the SSD for faster
read speed.
ZFS on FreeBSD etc. does it in its "ARC"/"ARC2L" feature?
There is some hardware solution, e.g. Intel made the
http://ark.intel.com/products/70029/Intel-RAID-SSD-Cache-Controller-RCS25ZB040LX
using the "Nytro MegaRAID" chip.
Someone would need to port its driver to OpenBSD.
Also in the past there was a "Adaptec MaxIQ". Those are the only two
"Raid controller cache" hardware solutions I am aware of, do you know
any more?
(Was not sure if this belonged on tech@ or misc@, any clarification for
me to never more crosspost please let me know)
