Microsoft details performance of Vista's SuperFetch, ReadyDrive

Boston (MA) - At a Wednesday afternoon session of TechEd 2006, Microsoft program manager for Windows Client Performance Matt Ayers showed off the performance of the very latest builds of SuperFetch in Windows Vista Beta 2. Ayers also confirmed, for a third time, what Microsoft documents now clearly state: Hybrid hard drives with ReadyDrive technology will be a requirement for mobile systems to qualify for the Vista Premium Logo in Q2 2007.

ReadyDrive is the name Microsoft is using for its technology for managing the Flash memory specifically in hybrid hard drives. Meanwhile, SuperFetch - its sister technology - is capable of requisitioning Flash memory from any device that presents memory to Vista including, as Ayers said Wednesday, including USB 2.0 keys, SD and CompactFlash cards, and even permanently installed Flash caches. The exception, he noted, are memory devices such as external USBs, which use drivers to report themselves differently to Windows.

In Wednesday's SuperFetch demo (pictures of which can be seen in our accompanying slide show), a battery of four applications were loaded in sequence: Outlook first, followed by OneNote, PowerPoint, and Adobe Acrobat. On an ordinary HP notebook computer, with a 2 GHz processor and 512 MB of RAM, the sequence of apps took 32.6 seconds of load time. With SuperFetch turned on, load time immediately improved to 26.5 seconds - a boost of 18.7%.

Frankly, that's not too impressive. But as Matt Ayers explained, SuperFetch is learning from its user about the patterns of hard disk pages it tends to load. Having seen the same sequence of data loaded into memory the same way twice before, SuperFetch then has reason to believe this may be a common occurrence for this system - for instance, a startup sequence. So for the third test, with exactly the same four apps, the load time was enhanced by about 206% over cold loading.

A standing-room-only crowd was on hand to witness Wednesday's demos. One attendee asked Ayers, how much Flash is too much for SuperFetch; in his words, is there a margin for diminishing utility? Ayers said the speed gain trails off, by current estimates, after a total Flash memory that exceeds 2.5 times memory capacity. So for a 512 MB machine like the one Ayers used in his demos, adding Flash capacity beyond 1.5 GB might not be very effective.

Another part of the secret of SuperFetch's and ReadyDrive's efficiency isn't just saving and fetching 512 kB blocks to and from Flash caches, but their insistence upon low-priority I/O - using a Windows thread that can be suspended to make way for everyday user events that run on normal priority. Shifting the workload to low priority actually dramatically reduces the number of work events required for SuperFetch transactions.

As Ayers explained, applications that need access to the disk, like virus scanners and disk defragmenters, don't need to interact with the user. They'd rather just get out of the way of the user. Using prioritized I/O in SuperFetch, the Flash memory manager can still do its job while another process, such as streaming video, is repeatedly "hitting" the disk at normal priority.

To test this out, Ayers presented another battery of application loads, the first of which was executed after the HP notebook was awakened from sleep state. Waking up - just like for people - is a slow process, and the second test loaded the battery of four apps cold in 48.1 seconds. With a secondary I/O process continually hitting the disk, a second iteration of the app loads took 86.3 seconds, with the test program counting 96,480 competing I/Os - simultaneous seek attempts from both the loader and the continual process.

With SuperFetch running in low priority I/O, and the continual process still running, a third battery of loads consumed only 35.6 seconds, with only 19,040 competing I/Os.

Ayers also touted ReadyDrive for being "your notebook's best friend." Powering down the hard drive rotor, he said, will noticeably improve battery life by as much as 15 to 30 minutes on an ordinary notebook computer (like his). He showed a video of a test made at Microsoft where a hybrid hard drive, on a system running Word, was fully accessible to the operating system 100% of the time, while the rotor was powered on for less than a third of that time.

Attendees noted how IT administrators and CTOs have been imposing restrictions on their companies' ability or permission to use USB keys in their systems, noting the security breaches that tend to result. Other Microsoft demos here at TechEd have touted a new feature of Vista group policy, that enables an Active Directory admin to forbid users or groups from installing USB keys on their systems. Matt Ayers said on Wednesday his team is currently working with the group policy team to finalize a kind of group policy exception, which would disable USB keys as ordinary storage devices, but enable them for ReadyBoost purposes only, as ad hoc read caches. But today, when the same question was posed to a different Microsoft program manager demonstrating such features as new group policies, he flatly stated that Vista would only be capable of enabling all USB keys or disabling them. So it remains true that different divisions of the company can maintain very different stories.

Still, SuperFetch, ReadyDrive, and ReadyBoost remain one of the major draws of this year's TechEd, and a cause for excitement and anticipation among admins and developers who were sorely needing something exciting to emerge at last from Vista.

On Monday, Ayers broke the news that hybrid drives would be a requirement, echoing an adjustment to language in the Windows Logo Program Requirements documents, the latest official version of which (they're no longer drafts) were released last Friday. Later that afternoon, Ayers confirmed the news for TG Daily by conferring with company officials who are responsible for the document. He repeated his pronouncement for TechEd attendees on Wednesday.

Ars Technica yesterday indicated that other Microsoft partners may be doubting the company's commitment to this requirement. In our reporting earlier this year, it did appear the company had retracted at least once its commitment to the requirement. News emerged on Tuesday questioning the validity of our Monday report. However, we're told that Microsoft has the final say with regard to its own Premium logo program requirements. As long as Microsoft stands by its story, we'll stand by ours.

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Hybrid hard drives to become Vista Premium requirement