Will someone please clarify what this file actually does? It’s the subject of much speculation and is fueling the Comodo flaming even further.

Did anybody sent a PM to egemen or open a bugreport topic about it?

Related feedback topics:

According to the informations thus far posted in different topics sfi.dat it is locked file and thus will not defragmented. It cannot be accessed before uninstalling CIS.

It is likely sfi.dat is locked for use by CIS and thus Windows Defragmenter ought to skip it like it usually does for windows swap file (pagefile.sys).

As the file is locked and it cannot be accessed, it cannot be deleted. Such locked files ought to be deleted at reboot using specific windows functions.

By naming alone SFI.DAT looks related to Comodo antivirus and its SFI feature. If so no wonder its protected.

In case it is confirmed the unistaller is unable to remove it, once notified the developers will surely address this glitch.

Windows Defragmenter ran fine here it completes the defragmentation task although it skips sfi.dat (1.5 Mb)

AFAIK locked files, like pagefile.sys, are not usually defagmented although some defrag appplications may not explicitly report about them.

Defragmenting Your Pagefile
How to defrag pagefile.sys and hiberfil.sys with PageDefrag

Hi - I’d also like to know more about sfi.dat - I’m using Comodo free AV and firewall, but when I try to do a system restore, it fails when attempting to extrack sfi.dat from the restore point. I have no permissions on the file and can’t change them either, so it may be that Windows can extract the file, but can’t overwrite the extant one.

Using Win7 build 7100 btw.

Is there one security forum where the Online Armour, outpost fans do not tries to trash talk CIS? (they are fanboys even if they won’t admit it) Its been going on for so long, none bothers to reason with these extremist anymore…

Luckily people are finding out how great CIS is anyway… :-TU
And in real life scenario, CIS is kickass, no matter what they might say at wilders… 88)

Also you should be fully aware how the dirt throwing at CIS has to do with money as well… CIS has gained a okay market-share, due to the fact that CIS has a higher level of security compared to most out there… Security companies are losing millions of dollars due to CIS huge success… Why buy Norton when CIS offers better protection for free? Or why buy OA when CIS is pretty much the same and less resource hungry + free?.. =)

CIS is locking down permission to alter and possible even access certain parts of your system due to its need for self protection, host protection and such. I can confirm what you say about the system restore… Iam afraid you might have to uninstall CIS prior to such actions or use the disable D+ permanently thing…

Unfortunately, not being able to use System Restore is a show-stopper for me - but thanks for confirming the issue.

Hi Guys
I actually turned off system restore because number 1, it will hide a virus if it is not detected. Number 2 if you play around to much with sr it stops working properly. I use Acronis True Image and it beats windows sr hands down. I do an image back up every 2 days and dont have to worry about losing data. Give it a go and see what you think.

BTW I cant wait to see how much more money Norton’s and the other big names are going to lose because of CIS. I personally think CIS is the best out there and its only going to get better. I havent had a virus problem for the last six months and believe me I am not very careful to what sights I go to. D+ is an absolute God send in my books. CIS will better that all the rest, just watch this space.
shadha :smiley:

So is there a way to delete this SFI.dat file? I had to do a reinstall of Windows 7 so when I went to delete the windows.old folder I couldn’t because of that SFI.dat file. I Can’t take ownership, can’t move it to another partition, nada. That file is the only reason I can’t delete that folder and its pretty damn frusterating to have a file that does nothing and can’t remove it.

sfi.dat can be deleted out of windows.old.

I ran across the same problem. Only trouble is that afterwards, I couldn’t go a sysrestore bacause sfi.dat couldn’t be found or some such message.

Here’s how i deleted:
Created a Computer Administrator account:
either use secpol.msc or
as a normal administrator go to a command prompt and execute:

after doing the above then thru the control panel |user accounts you can create a posssword for that COMPUTER ADMINISTRATOR account.

Boot up again and choose the computer administrator account to login in
then shut down your computer.

Boot up again but this time tap the F8 key frequently until you a screen which willl let you go to SAFE MODE.

Once in safe mode, Choose the COMPUTER ADMINISTRATOR account.

Run CMD.EXE as an administrator

using the good old faithful dos commands, navigate to the files in windows.old which you couldn’t remove, Delete with the good old DEL command these offending files, Delete all subfolders, folders till you finally get rid of windows.old folder.

exit from the command shell (type EXIT and hit return).

restart your computer.

Due to the problems I have trying to perform a system restore since then, I’m going to once again uninstall CIS, reboot the system, install CIS and then see if I can successfully create a restore point and perform a system restore to the created restore point.

That’s tomorrow’s job as must run now. Will post the results of my labors later as I’ve no desire to reinstall Win 7 RTM and all of my everyday software again.


Has anyone come up with an answer to Dch48’s original question?

“Will someone please clarify what this file actually does?”


CIS 3.11.108364.552

This file is where CAV’s keeps a list of clean files it has scanned before, until a AV update then it resets the file. (Stateful File Inspection)

Hey OmeletGuy, no wonder they call you comodo’s hero!

Thank You!



No problem, any day. :slight_smile:

I turn off restore point in windows XP, but I still defrag sfi.dat. What is sfi.dat and Why this file was protected???

Simple way to get rid of sfi.dat . If you have CIS installed,go to Defense+,My Blocked file,browse to Windows.old folder,select sfi.dat,move to blocked files.Apply,apply. Open My blocked files again,select sfi.dat,Delete. Works on Windows 7 for sure.

I don’t have a Windows.old folder.

works like a charm Darktrew, Thanks Much!

Feb 2012 – Still works like a charm Darktrew, Thanks Much!

Thank you Darktrew!
Just to clarify for CIS 5.9.xxx:
Defense+ → Computer Security Policy → Blocked Files tab
This problem was easily SOLVED!