The filtering process triggers quite a lot of database connections and several postfix connections. Therefore, the performance of the hard disk system is one very important parameter, especially fsyncs/sec. We introduced a small benchmark tool (proxperf) which you can run on the console (use it when the server is not under load).
Here is a sample output (one cpu, single sata harddrive):
CPU BOGOMIPS: 4289.64
HD SIZE: 6.89 GB (/dev/sda2)
BUFFERED READS: 116.38 MB/sec
AVERAGE SEEK TIME: 8.09 ms
DNS EXT: 46.26 ms
DNS INT: 1.05 ms (domain.com)
DNSBL: 35.47 ms (zen.spamhaus.org)
for actual hard drives, the result for FSYNCS/SECOND should be around 1000 or higher. Especially when you use hardware raid without write cache (and batteries backup), the performance concerning FSYNCS/SECOND could be quite bad (around 100) and the overall performance not as good as you expect.
To get the best performance out of Proxmox:
- Fast CPU, multi core cpu´s are recommended
- Hardware raid controllers with batteries backup and write cache enabled and fast hard drives (Raid1, Raid5 or Raid10)
- Fast DNS servers (maybe locally cached)