AppAssure backups stop making snapshots and you start seeing a flood of log errors in the event viewer reporting Log write failed for device \Device\HarddiskVolume (drive ?:).   the failure status code is the last word of the data. an error event occurred.  eventid: 0xcaa12433


I came across a website called Merrit Solutions that has a great little how-to on fixing the dreaded Log write failed for device \Device\HarddiskVolume (drive ?:) error you get in the logs when you have a System Reserve Partition with excessive or oversized AALOGS.

Thanks  Merrit Solutiions for keeping this thread alive.


Here are the steps to quickly resolve the issue.

  • Assign a drive letter to the System Reserved Partition in diskmgmt.msc. (This is the 100 Mb partition that works with the operating system.)
  • Make Folders in this newly assigned drive letter visible in Explorer Folder Options (unhide hidden and system folders).
  • Grant your current login account full access to the System Volume Information folder through Explorer Security Tab.
  • Confirm the existence of excessive  AALOG files or file sizes in System Volume Information Folder. (I had one AALOG file that was 77Mb.)
  • There should only be 1 AALOG… file, usually only a few KB in size.
  • If you do not see excessive or oversized AALOGS, do not proceed.
  • Issue “fltmc unload aafsflt” command in elevated Command Prompt (Run As Administrator) to release all of the AALOGs.
  • In elevated command prompt change to the disk assigned above in Step 1) and “cd Sys*”.
  • “del aalog*.*”to delete them.
  • Before closing the Command Prompt run “fltmc load aafsflt” to reload the filter driver and re-create clean new AALOGs.
  • When I deleted the AALOGs I got an alert from my core warning me to reboot the Agent machine.
  • Snapshot the machine again (you should see a Base and incrementals thereafter.)
  • Remove the drive letter assigned in the first step.
  • Restart the server or atleast restart the replay agent on server and logs should stop.
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