One of the coolest new embedded enabling features we introduced in XP Embedded SP2 is hibernate once resume many (HORM). It provides the ability to more rapidly boot an embedded system as long as the system is protected by enhanced write filter (EWF). Since SP2 shipped we have gotten a lot of questions from customers about HORM and EWF. In particular, many folks have wanted to know if it is possible to use HORM without the limitation that EWF is enabled for all partitions on a system. This would be useful, for example, if you have a jukebox device and want to store your music and playlists on a separate data volume and not necessarily protect that volume with EWF.
Our team has written a really good in-depth document about how to programatically dismount volumes in EWF and HORM scenarios so that you will not have to protect all volumes with EWF. It even includes some sample code to show how to dismount volumes in C. You can check it out by clicking here.
Hopefully this will be useful in your scenarios. If you try this strategy out please let us know how it works for you and also contact us via my blog or the embedded team blog if you run into any issues.