I had a bunch of problems here that delayed my tests. Hardware problems, other systems and so. Yesterday I started the tests and what I'm learning is really making it worth. I will send all the results latter but for now the biggest find is that the XFS filesystem of *the* best for maildir storage in comprassion from Ext3 in my case. I'll put all the results in the wiki in a few days (I can do it, right?). Unfortunatelly I couldn't test the ZFS filesystem with the OpenSolaris as my controller isn't supported.
I have a question here. It's easy to test but I would like to hear from a more experienced person. Say I use everything XFS for everything and I have 4 storages with 2TB each (after RAID10), I'll do Unify+AFR using GlusterFS version 1.3.12. So it will give-me 4TB of usable data. I'll store a lot of files, averaging 14KB for each file. What partition size should I use for the namespace cache (I'll do AFR on it too)? 40GB (1%) is enought? More? Less?