Could someone explain the new chkdsk options? What's an online scan?

By moeburn
in Microsoft (Windows)

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moeburn

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Could someone please explain what the new chkdsk options in Windows 8 mean/do?

 

  • /scan - Can only be used with a NTFS disk. Runs a online scan on the volume.
    • /forceofflinefix - Can only be used with a NTFS disk. Must be used with /scanswitch. Bypass all online repair; all defects found are queued for offlne repair (ex: "chkdsk /spotfix").
    • /perf - Can only be used with a NTFS disk. Must be used with /scan switch. Uses more system resources to complete a scan as a fast as possible. This may have a negative performance impact on other tasks running on your system.
  • /spotfix - Can only be used with a NTFS disk. Runs spot fixxing on the volume.
  • sdccleanup - Can only be used with a NTFS disk. Garbage collect unneeded security desciptor data. Includes the functionality of /f.
  • offlinescanandfix - Runs an offline scan and fix on the volume.

 

What is an "online" scan?  What is an "offline scan"?  How are these different from a normal /F or /R scan?  

 

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Newinko

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Windows 8's NTFS implementation is capable of online healing, which means that a drive needing NTFS structure repairs doesn't have to be unmounted. For more severe problems, though, offline scanning is required. The switch to offline scanning is on a need-to basis and is generally automatic; for fringe cases, you can force it with the /forceofflinefix if you so require.

 

Online scanning therefore means that the disk doesn't have to be unmounted to be scanned (meaning you can repair the boot drive without having to restart or an external drive without having to make it unavailable during the scan). Offline scanning means the scanned drive is unavailable during the scan, which means rebooting in command-line mode if it is the boot drive.

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George P Global Moderator

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Could someone please explain what the new chkdsk options in Windows 8 mean/do?

 

  • /scan - Can only be used with a NTFS disk. Runs a online scan on the volume.
    • /forceofflinefix - Can only be used with a NTFS disk. Must be used with /scanswitch. Bypass all online repair; all defects found are queued for offlne repair (ex: "chkdsk /spotfix").
    • /perf - Can only be used with a NTFS disk. Must be used with /scan switch. Uses more system resources to complete a scan as a fast as possible. This may have a negative performance impact on other tasks running on your system.
  • /spotfix - Can only be used with a NTFS disk. Runs spot fixxing on the volume.
  • sdccleanup - Can only be used with a NTFS disk. Garbage collect unneeded security desciptor data. Includes the functionality of /f.
  • offlinescanandfix - Runs an offline scan and fix on the volume.

 

What is an "online" scan?  What is an "offline scan"?  How are these different from a normal /F or /R scan?  

 

 

I believe that they mean the volume itself is either "online" mounted or "offline" unmounted.   Or however it was named before this.  Like when you did /F and or one of the other commands that would unlink/unmounts the volume and then scan/fix it.  If you did it or tried to do it to the primary partition/volume like C:\ it would tell you that you have to restart for it to scan.  But when you did it to other volumes or hdds running on the system it would tell you that any open links to those would be broken and that apps/services could mess up on you etc.

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moeburn

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Thanks for the info!  That's awesome, because my boot drive is an 8-year-old 500GB, and it now has 7 bad sectors, so I'm glad to know it can scan while mounted.  

So what's the point of the /offlinescanandfix?  Isn't it the exact same as /F or /R?

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Newinko

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More or less, though I believe that technically the /f and /r flags are now mainly to be used for non-NTFS volumes. The /offlinescanandfix is preferred on NTFS volumes from Windows 8 onwards.

 

As an added note, bad sectors on a drive are generally cause for great concern. Run a S.M.A.R.T. utility to find out if the disk is about to fail.

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moeburn

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More or less, though I believe that technically the /f and /r flags are now mainly to be used for non-NTFS volumes. The /offlinescanandfix is preferred on NTFS volumes from Windows 8 onwards.

 

As an added note, bad sectors on a drive are generally cause for great concern. Run a S.M.A.R.T. utility to find out if the disk is about to fail.

 

Yeah, I know all about the warning signs of a failing disk.  The only red flag according to SMART is the # of reallocated sectors (likely the same as the number of bad sectors, unless something else like a bad cable caused the sector to be misread) which is red flagged because the # is higher than 0.

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