TFS 2010 – Application Tier Version Control Cache Configuration details

The following applies to the AT cache only (the real proxy is close but not identical as it does not have access to the TFS registry)

The TFS registry is the first place we look for settings:

• /Service/VersionControl/Settings/FixedSizeBasedPolicy indicates a fixed size cache (in MB)
• /Service/VersionControl/Settings/CacheLimitPercent is the alternative (i.e. % of the available disk space occupied rather than fixed size)
• /Service/VersionControl/Settings/CacheDeletionPercent is how much of the cache should be deleted when the threshold is reached (think of it as hysteresis)
• /Service/VersionControl/Settings/StatisticsPersistTime is how often the statistics file is saved to disk (not so interesting)
• /Configuration/Application/DataDirectory indicates where the AT cache will live

We then validate those settings (or come up with default if not found).

1. If nothing is set, the default is CacheLimitPercent = 75%
2. If both CacheLimitPercent and FixedSizeBasedPolicy are set, FixedSizeBasedPolicy wins.
3. If CacheDeletionPercent is not set, it defaults to 20%
4. StatisticsPersistTime defaults to one hour (any value above one hour is acceptable).
5. DataDirectory can be overridden by adding a node in the web.config file like so (in which case it overrides the /Configuration/Application/DataDirectory setting):

<appSettings>

<add key="applicationDatabase" value="Data Source=dbserverhere;Initial Catalog=Tfs_Configuration;Integrated Security=True;" />

<add key="WorkItemTrackingCacheRoot" value="C:\Windows\Temp\TFTemp" />

<add key="traceWriter" value="false" />

<add key="traceDirectoryName" value="%TEMP%\\TFLogFiles" />

<add key="applicationId" value="GUID here" />

<add key="dataDirectory" value="E:\" />

</appSettings>

Important considerations:

• ·In an NLB environment, the TFS registry settings apply to ALL nodes, which is why the web.config settings take priority.
• CacheLimitPercent is a bit misleading in that if you have a 100GB drive and 50GB of other content, the TFS Cache can only use 50GB, so by default, the cleanup will occur when the cache reaches: (CurrentCacheSize + AvailableSpace) * (CacheLimitPercent / 100) = 50GB * .75 = 37.5 GB
• The Cache Cleanup can take a long time (hours on a very large drive) – so I would recommend changing the default Idle Time out on the Application pool to at least 60 minutes if you have a large cache and infrequent requests.

Fuente:http://blogs.msdn.com/b/girishp/archive/2012/01/21/tfs-2010-application-tier-version-control-cache-configuration-details.aspx