Why is chkdsk so much slower at boot time?

Something I've always wondered about: if I do a disk Properties/Tools/Check now and am successful i.e. the drive's not mounted and is checked (typically with just "auto fix" selected, not "check for bad sectors") it runs lickety-split i.e. usually less than a minute even on very large drives.

But if the drive is busy and has to be checked at boot time, after restart when the Windows boot process gets to the check (and after the count-down) it takes a much looonger time to do the check. Maybe not an order of magnitude, but 5 times longer typically.

It seems counter-intuitive that it would take longer at boot time to run a chkdsk vs. at the Windows desktop; shouldn't it be the other way around? Or is the boot-time check somehow more thorough than the check at Windows time? You'd think since that's all the machine is doing it would be fast as heck, or at the very least AS FAST as running it from Windows wouldn't you?



Another question please: If I want to check ALL MY DISKS at boot time before Windows loads, is this as simple as say running a batch file to set all the dirty bits then rebooting? I believe the command for this is

fsutil dirty set volume:

I have a PC with some 8 or 9 drives that I usually Hybrid Sleep, and sometimes I suffer hangs & crashes and lose track of whether I've done a chkdsk following (rare, but it happens) so I'd like periodically just to check everything at one time.

Why are you disk checking so often? Do you suspect HD problems? It would be better to monitor the drives with a program like Hard Disk Sentinel Trial version - HDD health and temperature monitoring or CrystalDiskInfo - Software to know its condition. The file system should auto-check itself at boot if it becomes problematic.

I only Disk Check my HD's approx quarterly including a Full Disk Check when I run Puran boot-time defrag.

maxseven said:

I've done a chkdsk following (rare, but it happens) so I'd like periodically just to check everything at one time.

I don't do this very often. But when I do it's a PIA, and I think it's odd that it's slower at boot than in Windows.

I already have Acronis drive monitor software and while that apparently does well to check SMART attributes I don't think it knows if an unclean shutdown has left a file system anomaly in place.