Normally CMOD will use a round robin algorithm in order to fill up each the cache directories that you have defined.
Officially every filesystem must be the exact same size.
So if you have a directory which is 100GB, then normally all directory must be 100GB.
In practice, what I notice is that CMOD look only for the percentage of disk usage on each cache directory, and not the size itself.
Therefore you could imagine having a small first cache directory and really big additional directory.
In that case, it will as you want. But you cannot stop CMOD to store actual data in the first cache directory. If he thinks, that he can fit a data file inside, then he will add it.
There is nothing you can do about it.
Now the first cache directory needs a LOT of inodes... because he have the links of every files that are copied into every cache directories... Therefore you must check that point very carefully especially if you are trying to keep this first filesystem small.
That said, the only information that is in the first cache directory, since you are not using TSM, is the "retr" directory, and if you look at it, you will understand quite quickly the structure of it.
And you will see that you can reconstruct it very easily... (at least in Unix/Linux, a small shell script can do it in a few seconds/minutes depending on how many objects are in the cache, I can show you an example if you want)
So my advice would be to keep all the cache filesystem at the same size, and don't bother to try having a smaller cache filesystem for some reasons, because it is not worth spending the time on that aspect of CMOD.
That's my own opinion :-) Maybe others have something else to say!
