Comprehensive RAID performance report

[Osiris]

Introduction
Storage is one of those things that we can never get enough of both in capacity and in performance. This article is going to compare a large set of RAID performance data and perhaps debunk some storage myths. I ran a large set of tests for my Intel ICH8R hot-swap platform and compared it to other RAID solutions on the market. See gallery of performance numbers here. I also want to give a special thanks to Eugene of StorageReview.com who let me use a large set of RAID performance data on other non-Intel RAID controllers. I've been a long time fan of StorageReview.com which offers in-depth storage articles and performance databases.
Hardware and software configuration:

• Intel DG965WH G965-based motherboard
• On-board Intel ICH8R Southbridge 6-port RAID controller
• Intel Core2 Duo E6600 2.4 GHz dual core CPU
• On-board G965 graphics
• 2 GB DDR2-533 RAM
• Four Seagate ST3500641AS-RK 500 GB 7200 RPM SATA-II HDD
• AMS DS-3151SSBK hot-swap pass through SATA cage
• See this blog entry for photos of this system
• Windows Vista x86 OS
• IOMeter for testing storage performance

Intel ICH8R RAID sequential throughput performance

As you can see from the throughput chart, the RAID5 (with four drives) all out sequential performance is out of this world at 218 MB/sec (1.744 gbps) read and 193 MB/sec (1544 gbps) write which only comes second to "Quad" which is four standalone drives being driven by four independent workers in IOMeter. As you can see, there is a computational cost to pushing gigabit throughput with parity calculations. At peak RAID5 sequential write throughput, the Intel 2.4 GHz dual core processor is pushed to a whopping 32% CPU utilization. [UPDATE 1:45PM - Note that the high CPU utilization ONLY applies to all out RAID5 writes at a blistering 193 MB/sec. All of the server-oriented I/O performance benchmarks in the next few pages never caused the CPU to go above 3%.]
This would have been completely impractical before the era of cheap commodity dual core CPUs and it would have used almost all of the CPU resources on a Pentium 4 3 GHz processor. It use to be that in order to get any kind of decent RAID performance, you had to buy a hardware RAID controller costing hundreds of dollars. A decent 8-port RAID controller capable of delivering anywhere close to this level of performance would have cost about $300. But with cheap dual core processors from both Intel and AMD costing just over $100, the era of cheap high-performance software RAID in the sub 8-port market is upon us. As Intel and AMD moves quad core processors in to the main stream next year, we'll begin to see software RAID solutions threatening the hardware RAID business at 8 ports and beyond.
With a capacity of 1.5 terabytes in a cheap hot-swap configuration, this is a superb solution for a business or a home. 1.5 terabytes is enough to store a 250-movie DVD library or 119 hours of miniDV (Standard Definition Digital Video) or HDV (1080i High Definition Digital Video). This also makes a massive high-performance fault-tolerant File Server for a business.


» Comprehensive RAID performance report | George Ou | ZDNet.com

[MrCoffee]

trouble with RAID 5 is that although the burst speed can be very high (i've seen upto 500mb/s with 4 drives) the sustained write is normally much lower than that of a single drive.

Mind you, the performance of RAID 5 can depend very heavily on the actual controller card used.

What the heck is RAID1x2 anyway?