Setting SMS 2003 Cache Tombstone Duration

If you are downloading before running a lot in SMS - i.e. making SMS copy the package down to its cache before running the program - you may have come across the problem that the cache is full, even though all your programs have finished and you'd expected that it had freed the cache entries.
Well, SMS keeps the cache entries around for at least a day - just in case you need it again, I guess. In normal circumstances, that could be ok, but if you are installing a fresh PC with a lot of packages, this cache strategy can get you in space problems.
Microsoft writes about it in KB 839513 - How the Systems Management Server 2003 Advanced Client manages its cache. Microsoft states that the cache tombstone duration is 24 hours.
Microsoft draws you attention to the SDK, especially the CacheInfo object. But this object only allows you to read the tombstone duration.
What they do not mention, is that you can simply tweak the cache tombstone duration, so the problem is gone or at least highly reduced. You do that by creating a MOF file - say SetCacheTombstoneDuration.mof - with these lines (sorry about the tiny font - I try to prevent the lines from wrapping)
#pragma namespace("\\\\.\\root\\ccm\\policy\\machine\\requestedconfig") [CCM_Policy_PartialPolicy(true)]
instance of CCM_SoftwareDistributionClientConfig
{
SiteSettingsKey = 1;
// Override only this property,
// all others come from the Site/Management Point
PolicySource = "Local";
// 5 min, default 86400 - one day
[CCM_Policy_Override(true)] CacheTombstoneContentMinDuration = 300;
};

Send the program to the relevant clients and execute it with -
mofcomp SetCacheTombstoneDuration.mof

That is all these is to it.

I cannot see that this method give any side-effects - but I also cannot guarantee it. If you experience any problems, please feel free to share your experience as comments to this entry.