Hi folks, probably an overoptimistic question... I'm looking to add a 8-16gb mini PCIe SSD card to my laptop to use in conjunction with my existing HDD which is obviously much larger. I need to achieve higher overall disk performance to avoid a bottleneck when using debian 6 on LUKS ecryption with virtual machines running.

My issue is that the mini-SSD will be too small to assign as both root AND host VMs, though arguably it could do one or the other. The ideal solution would be to create a virtual disk as a concatenation of the small SSD and large HDD, with the software controller moving the most accessed sectors to the SSD. This should give the most efficient use of the small amount of faster disk space. Whatever data gets accessed most, be it in home, root or even swap, would come from the faster device. Obviously failure risk would be increased over a single disk system, but I back up regularly and automatically anyway so I'm not too bothered.

I'm aware of commercially available hybrid SSD/HDD hard disks which do this, so it's certainly possible. It seems an obvious thing to pursue in this era of multi-terrabyte HDDs and blistering fast but smaller SDDs.

Anyone aware of any software solution which would do this?