Patrick Ben Koetter put forth on 8/10/2010 6:37 AM: > * Bjorn Mork <[email protected]>: >> i have tried to answer your queris, (Please correct, if I am wrong in >> understanding your question...) >> >> We do have multiple IBM Blade server with 2.4 Xeon + 16GB + NAS over iSCSI >> protocol...... >> >> How many blades will be involved for such load....???
16GB should be able to handle an insane number of simultaneous SMTPd processes especially if you use Postscreen, which I'd highly recommend with the user count you're talking about. This is highly dependent on your Postfix restrictions, anti spam daemons and virus scanners. Postfix, and SMTP in general is not CPU bound, so with dual 2.4 GHz CPUs, even if they are the "NetBurst" architecture, you'll run out of other resources before CPU bandwidth. The main one being... Storage, the most important aspect of your inquiry. You mentioned iSCSI and NFS, which at face value doesn't make sense. You don't connect an NFS client to an NFS server over iSCSI. iSCSI is for block level disk access and functions almost identically to a fiber channel SAN. iSCSI works at the block device level underneath the filesystem. NFS works _at_ the filesystem level. I'll assume you're actually using NFS, not iSCSI. Given your load, you'll need at least 2 GbE links on the Postfix servers--1 for inbound SMTP connections, and other for access to the NFS server, and these should be on separate ethernet and IP networks (different switches and subnets from the incoming smtp traffic) for security and other reasons. SMTP mail is primarily a disk bound application. You need a very high seek rate--high IOPs--as the mail flow is going to be lots of small files, including queue files and files permanently written to maildir on the NFS server. Would you please post the NFS/NAS server manufacturer, NFS/NAS server model number, number of disks and their RAID (stripe) level, and what types of disks--i.e. fiber channel, SCSI, SAS, SATA, etc? The random IOPs performance of your NFS/NAS server will be the overall performance limiting factor, if it's not sufficiently beefy. -- Stan
