On a workstation running Windows 7, I've created new NTFS partitions on the HD using Paragon HD Manager 8.5. After rebooting Windows 7, chkdsk ran automatically and found no problems. It apparently left in all the new partitions, as well as in the original (System, Boot) one, a (small: 4 kB) file called "bootsqm.dat". a) Is it true that the "bootsqm.dat" file was left over by chkdsk, as I guessed? b) Can this file be safely removed, or this would compromise any functionality? c) What's the use of this file? Thank you in advance.

This file only gets created when you run some software that requires to chkdsk (Disk Check) when computer is rebooted, after the task is complete and the operating system is running, you can safely delete this file. It doesn't replicate after deletion because it is no longer needed, it will only appear again when you will run another Disk Check at system reboot. AFAIK presence of bootsqm.dat indicates that the disk was checked (chkdsk) and this probably "fixed" some errors on the disk. I guess during this process access to your data was somehow lost. MCSE, MCSA, MCDST [If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.]

Thank you very much for the answer and the detailed information. Just one additional question: do you know if the described behaviour (chkdisk running at reboot creates a bootsqm.dat file on all the partitions that have been checked) and its implications (the bootsqm.dat files can be safely deleted after the OS is back on) are officially documented in any MS Windows document or online knowledge base resource? Thank you again in advance.

During my research I have not found any official documentation and I normally don't have or use multiple partitions but use multiple drives on servers so I'm unable to verify if the file resides on multiple partitions but it would seem logical that it would if you instructed chkdsk to check and fix errors on those partitions/drives at boot.MCSE, MCSA, MCDST [If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.]

Thank you very much. By the way, after a new reboot, the bootsqm.dat files were gone from all partitions. It looks like they are just a temporary leftover by chkdsk. It's just unfortunate that the chkdsk documentation doesn't mention the issue at all.