Solve a VMWare/Parallels and Sophos Anti-virus slowdown

Mar 20, '09 07:30:02AM

Contributed by: gerritdewitt

For those who run Sophos Anti-virus (4.9.19 is presently current) with a Mac OS X 10.5 system and a virtualizer like VMWare Fusion or Parallels Desktop, this may be very helpful.

It appears that a recent update to Sophos Anti-virus can seriously interfere with the operation of either Fusion or Parallels. Upon opening either application, Sophos' main on-access scanner (InterCheck) will begin to consume large amounts of processor time. Checking in Activity Monitor or via top will reveal it at the top of the list. During this flurry of activity, neither Fusion nor Parallels is responsive. After a several minute wait, both may momentarily become responsive, only to slow down again. The slowdown is most pronounced when a virtual machine is being resumed from a suspended state. Stopping the Sophos on-access scanner returns Fusion or Parallels to their normal responsiveness.

Obviously, stopping Sophos solves the problem. However, some users may be required to run anti-virus software as part of their institutional rules, so that may not be a practical option. Instead, you can instruct Sophos to exclude the location where you've installed the Windows virtual machines from its on-access scanning:

  1. Open System Preferences and choose Sophos Anti-Virus. Authenticate as a local administrator by clicking the lock icon.
  2. Temporarily stop the On-Access Scanner by clicking the Stop button (under the Scanning tab).
  3. Choose Exclusions from the General pop-up menu, then click Choose and navigate to the folder where you keep your Windows virtual machines.
  4. For Parallels Desktop, the default VM location is ~/Documents/Parallels. For VMWare Fusion, the default VM location is ~/Documents/Virtual Machines. You can exclude those entire folders, for example.
  5. Restart the On-Access Scanner by clicking the Start button (Scanning tab, General pop-up menu).
And, since it will probably come up ... do you really need anti-virus software for Mac OS X? Well, Sophos labs lists a whopping nine entries in its Viruses and Spyware section. The point is that some people may be in a situation where they must run anti-virus software, Mac or not, so this may be of use.

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