IIS 5.0 file size limit

Every morning for a week my monitoring software woke me up with an SMS at 4 AM because a Windows 2000 server had inetinfo.exe runinng 100 % of CPU, I tried to stop the service, I tried using iisreset and also tried with pskill but the inetinfo process was still consuming CPU.

After inverstigation, I understand that IIS 5.0 has a bug when trying to download a file larger than 4,294,967,296 bytes through FTP or even HTTP.
A part of the file will be downloaded to the requesting client, then you will notice inetinfo spins up to 100%CPU; looking more closely you will notice the CPU time is in kernel mode and not user mode.

I asked on MS IIS Private Newsgroup and they confirmed that it's a bug with IIS 5.0, the problem doesn't occur on IIS 6.0, actually no hotfix has been released .

About author

Vittorio Pavesi