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Some machines in the new XPS laptop range from Dell come with a regular, large (500GB+) HDD and an additional 32GB m-SATA SSD. The only detail I can find about this extra drive on the Dell site is this:

Store your important files, multimedia and photos with XPS 15’s large hard drive options. To get instant access to your media, choose an optional mSATA solid-state drive (SSD) that can boot up to twice as fast as a regular hard drive and resumes in less than 1 second.

I'd like to know more about how this extra drive is set up and used, specifically:

  1. Is anything installed on it (e.g. OS files or a boot loader) or is it just used as swap space?
  2. Is the m-SATA drive visible as a lettered drive in Windows? (I'd guess not if it's used for swap file only.)
  3. Is this unusual configuration likely to cause any problems later down the line - e.g. when upgrading to Windows 8?

As usual, Dell's sales team haven't been able to help. If anyone's actually got a Dell machine with this or a similar hard drive set-up and can give a definitive answer rather than speculation I'll accept the answer.

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Dell laptops with an mSATA SSD built in are in a RAID configuration enabling Intel's Smart Response tech to store a cache of the most used files on the SSD. This means faster boot times, application start times, etc. You can upgrade the built in mSATA to a bigger SSD, then go to the BIOS and change drive configuration to AHCI. You would have to re-install your OS but you can then install it on the SSD and use the hard disk as storage. This is my configuration and so far I have been happy with it with 4 second boot times to Windows 8. You really do not gain much if any battery life doing this, but the performance advantages in themselves are outstanding. I would caution that if you go this route, you should NOT install Intel's AHCI drivers as they are not compatible with the hard disk and would cause it to disappear for Windows (not the BIOS). Just use Microsoft's drivers and you'll be fine.

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up vote 8 down vote accepted

In the end I went ahead and bought the Dell XPS 15 so I'm now in a position to answer the question myself. The 32GB mSATA SSD is used to enable a range of Intel features - Rapid Start, Smart Response and Smart Connect - referred to collectively as Intel Responsiveness Technologies (PDF).

  1. No, nothing is installed on the SSD (at least, nothing the user can see or directly access). An Intel Rapid Storage application is installed on the regular HDD, accessible via a tray icon in Windows, which is used for enabling and monitoring Intel Responsiveness features.
  2. No, it doesn't appear as a lettered drive in Windows or at the command prompt.
  3. Too early to say. :)

The reference to booting "up to twice as fast" refers to Rapid Start, a proprietary hibernate-like feature which Intel claim is twice as fast as starting from a native Windows hibernate.

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  1. To get the machine to boot fast, you need to put the OS on the flash drive.
  2. The pagefile needs to be on a labelled drive.
  3. It's not an unusual configuration :)
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Specifically in the Dell XPS L521X the 32GB drive uses both Intel Rapid Start & Intel Rapid Storage Tech. Warning: If upgrading system RAM; Rapid Start needs to as big as or bigger than system RAM (I believe it comes from DELL at nearly 3X system RAM on a 6GB system); The Rapid Storage uses 18.6GB. So, If upgrading to 16GB System RAM, only 1 or the other will work with the 32GB mSATA SSD. If upgrading the main 2.5" Hard Disk to an SSD drive then the mSATA drive becomes irrelevant and is no longer necessary for the Intel Rapid Response Technologies. Ref:

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