XP From A Flash Device 

Our first scenario involved getting Windows XP Service Pack 2 installed and running from a 2GB Compact Flash card, not an easy task. The PQI 120x Compact Flash cards we used were "removable device" cards, so some additional preparation has to be taken into consideration in the case of XP. We tried a direct installation of XP SP2, thinking we could install, then tweak our way back down, but that was a bit foolish. Firstly we hadn't taken into account there being no space for XP's default swap file (Yes even review writing guys forget to think sometimes). Secondly, despite successfully formatting and installing core files from an XP SP2 CD boot, upon reboot the drive would not boot. The workaround here wasn't too hard. You can either use a DOS boot floppy or CD and FDISK and FORMAT the device, or use 3^rd party utilities like MBRFix to place a Master Boot Record on the flash drive. Once you have that step out of the way getting a Windows OS to boot isn't a chore. Filesystem overhead wise, your best off sticking to FAT32, though NTFS will work just fine.

We proceeded to perform our XP install on the Hitachi hard drive, then used XPLite to pair down installed accessories and services, though we didn't aggressively do so. We mainly got rid of fluff like IIS support, native XP Games, Accessibility Support and the like. We also disabled System Restore, Hibernation support, the Virtual Paging file, and the file cache for Internet Explorer. Our goal was to reduce installation size and reduce the need for writes.

Another way to have approached this that would have been wiser in a wide deployment scenario would have been to use Nlite to create a customized install. An even more attractive method for wide deployment would have been to deploy XPe (XP Embedded Edition) SP2. Actually utilizing and deploying XPe however is rather complex and beyond the scope of what we were trying to do, so we left that for another day. XPe does offer some features particularly friendly to flash memory deployments however, most notably it's use of EWF, or Enhanced Write Filtering, which allows writes to be cached in RAM and committed during device shutdown. Microsoft offers downloadable evaluation versions of XP Embedded here.

We were able to get our install image down to roughly 1GB in size, so once we did that and had the CF card prepped with MBRFix, we booted with another XP installation from a spare Seagate 120GB HDD so we could simply transfer the files from the Hitachi drive to the PQI Compact Flash drive. After that it was a simple matter of shutting down swapping the Addonics CF adapter to the position of the boot device and rebooting. A minute or so later we were greeted with the ever familiar Windows desktop.

We spent the better part of an afternoon toying with this setup, and found it a little sluggish but usable. Further pairing down of services, or investing the time in rolling on XPe would have allowed more noticeable gains in performance we're quite sure. To give you a better feel for the setup we did do a few benchmarks, utilizing HDTune, PCMark 2005, and simply stop watching XP Startup and Shutdown times.

Startup and shutdown times more or less speak for themselves. The Hitachi HDD install was significantly faster in startup, but not that much different in shutdown times at all.

HDTune revealed an anomaly with the PQI 2GB CF cards we were using. Rated at 120x (120 times 150kb/sec) according to the retailer we bought these from, their actual performance was closer to 75x devices. This was borne out with separate testing with a USB CF card reader, so no fault of Addonics's adapter. Average read speeds stayed in the 10MB/sec range which is way slow compared to what you'd expect from even the slowest of notebook drives. Average access time however was extremely low, at 2.4ms, and shows the one performance advantage you have when not tied to mechanical read/write heads. The build installation Hitachi drive, which is no speed demon as HDD's go, way outclassed the Compact Flash card in every performance metric except access latency, which is no suprise.

We used PCMark 2005 primarily to give a better impression of the "feel" of the installation, rather than actually relying on it as a real world benchmark. We avoided utilizing the overall PCMark score and instead focused on individual test results in the standard suite that deviated from one another significantly. We did it this way to better show some of the inherent strengths and weaknesses of Compact Flash when used in this manner. Our intention is to show you what medium your working with rather than bashing it because it's slower than a HDD, something we already know.

Two tests in particular showed where the actual test itself was bound by the devices overall transfer speed. File Decryption and Multithreaded Virus Scan clearly showed the "brick wall" generated by the devices read speed. The rest of the tests where file I/O were at least part of the equation were mixed wit h the Compact Flash card fairing favorably overall.

Overall our experience was mixed, but generally favorable. It's quite clear that optimizing an installation for Compact Flash takes some effort in this sort of OS strategy. An organization planning on deploying field systems this way would probably invest the time and effort into deploying XP Embedded Edition in order to reap positive gains in system battery life and support. We see potential positive uses in the retail/field TabletPC, subnotebook, and PDA markets with this sort of storage medium, and indeed flash memory technologies are already widely deployed in these areas.

Now, on to something a little more fun.