How long should a Windows 7 upgrade really take?

How long does it take to upgrade from Windows Vista to Windows 7? Last weekend, several leading tech websites zeroed in on one alarming snippet of data that a Microsoft tester published on his Technet blog: With the right combination of hardware and data, a Vista-to-7 upgrade can take more than 20 hours. That data point leaves plenty of room for snark and trepidation. But does it actually represent performance that you’re likely to encounter in the real world? I've got the real story.
Written by Ed Bott, Senior Contributing Editor

How long does it take to upgrade from Windows Vista to Windows 7? If you said 20 hours, you need to go back to school.

Over the weekend, several leading tech websites zeroed in on one alarming snippet of data that Microsoft tester Chris Hernandez published on his Technet blog: With enough data, on sufficiently underpowered hardware, Microsoft found that a Windows 7 upgrade from Windows Vista SP1 can take as long as 1214.86 minutes, which is (hang on while I fire up Calculator here) … 20 hours, 14 minutes, 52 seconds. Give or take a few milliseconds.

That data point leaves plenty of room for snark. But does it actually represent performance that you’re likely to encounter in the real world? In a word, no.

For starters, if that sort of performance were common, we would have heard about it already from the 8 million or so people who installed Windows 7 in its beta, RC, and RTM releases. Yet I don’t remember reading any such complaints. Do you?

Over the past 10 months or so, my co-authors and I performed literally hundreds of Windows 7 installs while researching Windows 7 Inside Out. Based on that experience, here’s what I believe you can expect:

  • A clean Windows 7 upgrade, over a new or restored Vista installation, should take 30-45 minutes. That matches up perfectly with the data reported in Chris’s blog post.
  • With 50GB or so of user data, you can expect the upgrade to complete in 90 minutes or less. Again, that finding is consistent with the Microsoft data.
  • On reasonably modern hardware, most upgrades will take less than two hours. (I talked to one professional videographer today who reported that he had upgraded a system containing nearly a terabyte of video files in roughly an hour.) Factors that can slow down upgrades include slow hard disks (such as the 4200RPM models found in some ultraportable PCs) and excessively full disks.

So where do those huge test numbers come from? Those are the results of stress tests performed by Microsoft to measure whether the upgrade experience in Windows 7 is improved over its Windows 7 predecessor. To measure that performance, testers clocked total upgrade times on three different PC configurations with four different data sets, ranging from no data (a clean upgrade) to a massive 650GB of user data and 40 programs whose files and settings need to be migrated.

It’s hard to reproduce the test conditions precisely, because Chris’s post lacks some basic information. (And the visual presentation is ghastly – can someone please give these engineers a course in how to create charts that actually tell a story?) But I was able to duplicate a couple of the configurations and also compare the reported performance versus my experience. Here are some observations based on those experiences:

  • Windows 7 installs are unquestionably faster than Vista installs. The Microsoft data shows that upgrade times are at least 6% faster and in many cases more than 20% faster, especially for 64-bit installs. (That 20-hour install actually took an extra 90 minutes using Vista on the same hardware!)
  • Your performance is almost certain to be better than these test results. I duplicated one set of tests almost to the letter, upgrading a reasonably fast quad-core system with a 7200RPM disk containing 125GB of user data. In the Microsoft tests, the total upgrade time was 151 minutes; my upgrade completed in 103 minutes, a 30% improvement.
  • The data sets in Microsoft’s tests are thoroughly unrealistic. Chris tested three different data sets—70, 125, and 650 GB. Let’s put that into perspective, shall we? My digital music collection is massive, with 21000+ tunes, a third of them ripped in lossless formats. I have more than 8000 digital photos, half snapped with a 10MP camera. I have copies of every e-mail message I’ve sent and received since 1995 and every book and article I’ve written since 1998. Collectively, those files add up to 212 GB. The only people I know with 650GB data collections are professional videographers and BitTorrent addicts.
  • You can improve upgrade performance with some common sense. I list some things you can do in my companion piece, The Windows 7 upgrade survival guide.

After looking carefully at the reported results, I think I know why the reported test results don’t match up with real world experience. My data sets mirror what you’re likely to see on any computer—some Word documents and Excel spreadsheets, PDF files, JPEGs and MP3 files, plus scattered ISO Images and executable files. By contrast, testers are likely to create synthetic data sets consisting of many small files with arbitrary names. Windows setup is a meticulous, journaled process designed to be error-proof and to be completely reversible; the more files you throw at it, the longer the process will take, especially if the disk is already full.

Have you kept track of setup and upgrade times with Windows 7? Leave a comment in the Talkback section and share the details.

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