RsyncServer not started because pid file rsyncd.pid exists

I had a scary experience today because one of my Windows PCs “blue screened”, i.e. it crashed. While the “Blue Screen of Death” was fairly common in Windows 95 and 98, it is unusual to see it on any healthy machine running Windows 2000, XP, 2003 or 2008 Server, Vista or Windows 7.

Since the CPU fan of the machine had been running faster than normal recently, I had already suspected it of dust buildup in the CPU heat sink and when I opened up the machine, my suspicion was confirmed. I pulled out some dust and vacuumed the machine before starting it up again.

The machine booted normally and the fan was quiet, but I got alerts from another machine that it could not connect to the Rsync server of the restarted machine. I use an Rsync service for Windows to synchronize data updates between various machines. The service was shown with startup mode “Automatic”, which means it should start whenever Windows is booted, but it was not showing as “Started”. Looking into the log file at “C:\Program Files\ICW\rsyncd.log” I found several of these error messages, one each for every restart I had performed after the crash:

2010/05/08 15:37:45 [2128] rsync: failed to create pid file rsyncd.pid: File exists (17)
2010/05/08 15:37:45 [2128] rsync error: error in file IO (code 11) at clientserver.c(985) [receiver=3.0.6]
2010/05/08 15:52:32 [2120] rsync: failed to create pid file rsyncd.pid: File exists (17)
2010/05/08 15:52:32 [2120] rsync error: error in file IO (code 11) at clientserver.c(985) [receiver=3.0.6]
2010/05/08 16:11:13 [2644] rsync: failed to create pid file rsyncd.pid: File exists (17)
2010/05/08 16:11:13 [2644] rsync error: error in file IO (code 11) at clientserver.c(985) [receiver=3.0.6]

Probably the sudden crash had prevented the Rsync service from deleting its pid (process ID) file, as it normally does when it is shut down orderly.

After I deleted “C:\Program Files\ICW\rsyncd.pid” I was able to start the service and the other machine could connect to it and synchronize with it properly.

Hopefully the machine will keep running reliably again now that the heat sink is clean again. I will keep checking it for dust buildup at least monthly now that the summer months are approaching.