In the latest Building Windows 8 blog, Kiran Bangalore, Senior Program Manager of Microsoft's Windows Core Storage and File Systems, said that one of the key design goals for Windows 8 was to increase availability and reduce the overall down-time of systems. This design feature, along with other storage features such as Storage Spaces and the new ReFS file system, will help reduce the complexity of fixing corruptions and increase the overall availability of the entire system.
In other words, less downtime due to file system corruptions thanks to a redesigned chkdsk utility and a revamped NTFS health model.
In previous versions of Windows, the NTFS used a simpler health model: the file system was either healthy or in bad shape. This model meant users typically had to stop what they were doing and wait for chkdsk to take the disk offline, fix the file system corruptions and bring the volume back to a healthy state. The bigger the problem, the longer the system was offline. The process could take seconds, or last for hours.
"In Windows Vista and Windows 7, we made significant optimizations to the speed of chkdsk, but as hard disk capacities have continued to double every 18 months and the number of files per volume is increasing at an equal rate, chkdsk has taken longer and longer to complete (even with speed improvements)," Bangalore writes.
To speed up the process, Microsoft has revamped the health model used by NTFS and introduced the ReFS file system in Windows 8 which does not require an offline ChkDsk to repair annoying corruptions.
"We developed a new method of communication that describes types of corruptions as 'verbs' that act upon the key components and points of the design – the file system driver (NTFS), the self-healing module, the spot-verification service, and the chkdsk utility," Bangalore continues. "All file system corruptions are classified as needing one of 18 different 'verbs' that we’ve defined in Windows 8. We have also left room for possible new verb definitions that can help us diagnose issues even better in the future."
Bangalore said that Windows 8 can scan for problems in the background while the system remains online, and will make an initial attempt to fix problems on-the-fly. If the initial fix doesn't resolve the issue, then NTFS logs the details, how the repair must be done, and stores the info away until the system is restarted. This way, the process won't take quite so long after boot.
"The downtime from this operation, called 'Spotfix,' takes only seconds, and on Windows Server 8 systems with cluster shared volumes, we've eliminated this downtime completely. With this new model, chkdsk offline run time is now directly proportional to the number of corruptions, rather than being proportional to the number of files as in the old model," Bangalore says.
Also in the blog is a Q&A explaining that the new health model will be enabled by default and work with removable drives that report fixed media. Consumers can also move between Windows 8 and Windows 7 and not affect the file system health model -- the file system health model will adapt to whichever operating system version it is mounted on. The Q&A also states that ReFS follows a different model for resiliency and does not need to run the traditional chkdsk utility.
For more information about the new NTFS health model and the redesigned Chkdsk utility, head here.