On Thu, Mar 19, 2009 at 6:52 PM, Brandon Hilkert <bhilk...@vt.edu> wrote: > Our test system is a pretty standard SATA disk with 2GB memory. If disk is > the necessary resource, would we see an immediate benefit by going to a SCSI > disk or even a SCSI array, or does that hardware benefit flatten out at some > point?
Postfix performance is primarily limited by how fast the disk can sync data. For standard rotational disks, this is going to be primarily limited by how fast the disk rotates. Since your standard SATA disk reotates at 7200 rpm, replacing it with a disk that spins faster (10k or even 15k RPM) will help immensely. There are 10k SATA disks available, otherwise you have to go SCSI. Expect up to a 30% improvement with a 10k rpm disk and nearly double with a 15k rpm disk. If you want to go significantly faster than that, you have 3 options: 1. More spindles and the appropriate RAID setup. A RAID10 array with 4 disks should double your random IO performance. 2. IO controller with battery-backed memory cache in write-back mode. The battery backed cache will basically allow syncs to happen nearly instantly (as long as your cache isn't full). This can improve performance by an order of magnitude. 3. SSD (Solid state disk). Intel makes some great SATA SSDs that will absolutely fly under this kind of workload. But before you buy any old SSD, I highly recommend you read this article at Anandtech: http://www.anandtech.com/storage/showdoc.aspx?i=3531 4. A combination of 1 & 2 or 2 & 3. Hope this helps. -Dave
