Today I was reminded again of the fact that the only current virus-related threat on OS X are the antivirus software themselves:
That's 442 different VirusBarrier processes spawned off for no apparent reason in a totally normal user environment (Mail, Safari, TextMate etc). I noticed the problem when I tried to open an SSH connection but got the following error instead:
-bash: fork: Resource temporarily unavailable
That means the system has exceeded the limit of processes per user, which in Leopard is already pretty generous:
filipp$ sysctl kern.maxprocperuid kern.maxprocperuid = 1000
So I was unable to open any applications and slowly the machine just started to die. Simply disabling the automatic virus check didn't do anything, but luckily a good-old killall saved the day. Needless to say VirusBarrier has now been uninstalled.
I only installed it since it came as part of the Macupdate Promo Bundle, wanting to see if it was any better than McAfee's VirusScan, which believe it or not is even worse. If you use 10.5, FileVault and VirusScan, your machine is guaranteed to freeze within 15 minutes after login. McAfee knows about this problem, calling it a “performance issue” and seem to have just recently released a patch.
So anyways, I think it's important that people abstain from installing antivirus software “just in case” and only do it when there's actual need for it. I thought the “performance issues” were a thing of the past, (remember the Norton installs that hosed entire systems when the OS was upgraded?), but clearly they still do more harm than good.