As I was Googling around for something I came across this post from Warner Crocker in which he explores the question: Will Windows Vista ReadyBoost work with SD Cards (and other Flash media) or not?
(He posted this at the beginning of the month - don't know how I missed it then!)
Well the definative answer from one who has tried it with multiple Tablet models is... *drumroll*
Maybe.
In fact it aboslutely will work provided the OS can read from the card fast enough to support ReadyBoost. Whether or not it can depends on two factors:
- The speed of the flash reader.
- The random read speed of the media.
The Reader
I know from experince that all card readers are not created equally. I have not been able to get any SD Cards to work in a Lenovo X41T - including the ones that work in my Toshiba M400.
The Media
The speed of the media is the other critical factor. The sad news is those speed ratings on the card don't actually provide a meaningful indicator of wheter they will work or not. I have a 120x card that works and my colleague has a 133x that does not - in the same tablet. The reason for this is the cards are rated using a process that writes a file to the card and then reads it off again - which is of course a sequential read. When Vista tests the card to see if it is fast enough it performs a random read. ReadyBoost is trying to boost system performance in part by servicing random read requests off the flash card rather than from the page file on disk - so the random read speed is what is important.
Why the difference you ask? When I was chatting to a MS guy at TechEd in Boston he told me that some cards have a chunk on "good" flash up the front and cheper, slower flash providing the bulk of the storage. As such the perform well for the sequential rating test but still are not fast enough to pass the random read test performed by ReadyBoost.
Figuring out what will work
It is hard to know which media is going to work and which isn't - and this will no doubt add to the confusion. The best advice I can give you is to take your device into the shop and insist you can try before you buy.
To know if your Reader is going to be fast enough you will either need to find a card that you know works in other devices or try to find reference to someone who has made it work. Here's my results so far with a known good SD Card:
Motion Computing LE1600 - Worked
Lenovo X41T - Too slow
Toshiba M400 - Worked
Motion Computing LS800 - Have not been able to make the SD Card reader work in Vista as of yet :(
The last point I'll add is that it is so worth the effort. Even on a well speced machine (my M400 has 2GB of RAM) it still makes a noticable difference to the performance of the machine. Hopefully this post helps clear some confusion instead of adding to it...