Problems in AppFabric max memory size

Question

I use Windows Server AppFabric, Cache Cluster contains two nodes on Windows Server 2008 R2 (server1 and server2), Cluster Configuration Storage Location is SQL Server.

In config file we have the following configuration:

        <hosts>
            <host size="6191" leadHost="false"  name="SVC1" cachePort="22233"  ...... />
            <host size="6191" leadHost="false" name="SVC2" cachePort="22233"   ..... />
        </hosts>
So as I understand max size for each node should not be greater than 6GB. But actually it very often more than 6GB (about 9GB). So we have to restart our cache cluster every 24 hours.

How can we fix this problem?