Can I cache an mdadm raid with an ssd?

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http://askubuntu.com – I have a 1tb array set up in raid 1 using mdadm on Ubuntu 8, to store mission-critical files. I'd like to speed up read/write, especially for large files by caching to an SSD. Is this possible? Does mdadm contain a facility to cache to another drive? Alternatively, is there something I should do to assign ordinary RAM to caching? There is 4GB RAM and files to be written are rarely larger than 1GB so I'm thinking writes should be quite quick just with RAM caching alone. Any help will be greatly appreciated. (HowTos)