A few Days ago we switched one Domain to a ISPConfig System with about 500 Email addresses. After switching the DNS we had a really performance problem on this machine.
I'm sure that the problem comes from our special Install on a virtual machine. All Disk writes in the VM are block writes on the Host. For redundance we use a DRBD drive (there are 2 Hosts, and all Data Dirs are mirrored with DRDB to the other machine).
Normaly we had no problem. Until now we used a own ISP software config. The old system has no performance problem in this environnement. But our software isn't good enough for future and that was the reason to change to ISPConfig.
The problems caused only by CLAMAV and Spamassassin. If I had a possibility to write temp files to a ram drive or a drive outside the DRDB drive, I think the performance will increase. But I cant find the matched configurqation files in the ISPConfig environnement where to change that.
I also have some troubles with iptables. I have a customized iptables and plan to use it for the system. But after a few minutes/hours (?) anything changed it to a default iptables. I think Bastille-Firewall does this, but I can't also find where this default iptables is. If I find it, I can also replace it with my own.
Maybe some stupid questions for Linux enthusiasts, but I'm new in this business, and now I learning by doing. Our old system was configured by a fried who has no longer time to do that ....
Thanks for any hints