Friday, September 19, 2008

Testing Build Times with RAID 0 on a Dell Precision

Machines from Dell can easily be configured with a RAID controller these days. I was curious to see: Would using RAID-0 (striping) improve build times? The short answer: no.

On one hand, I'm not surprised. On the other, I really wanted to give it a true scientific test, with real parts and a real workload. It's so easy to purchase machines configured this way, we might as well be buying machines in an optimal config.

I've been wanting to run this test scientifically for a while now. So I jumped on a new Dell Precision T5400 that had been ordered, and had it configured with a second hard drive (320GB SATA 3.0Gb/s, 7200RPM HardDrive with 8MB DataBurst Cache).

I installed Vista, Developer Studio 2008, DirectX August 2008, and Gamebryo 2.5. I built the Debug configuration of the first sizable solution (CoreLibs) which contains 11 fairly small libraries. Then I did it all again with a RAID0, 128kb block size. Build times were equivalent at 1 minute 15 seconds.

Now, I'm a graphics guy, not a hardware guy -- so maybe I overlooked something. If so... ;) let me know. I'll hold off a few days before I build up this machine for production use. At the moment, I'm planning on not using a RAID configuration.


  1. When you get a new system, your performance from your hard drive is much faster as most of the data is being written as quickly as the drive can process it. Once you have been working for a while and your drive starts to fragment you will see reduced performance. I imagine that striping will simply hinder that reduction.

    If you really want to know the fastest that you system will ever be able to compile then get a bunch of ram and create a ram drive. That would be your baseline. Then your non-striped drive system would be your slowest system and your striped drive system would likely be somewhere in between... but due to disk caching and data layout with a clean system, you may find all three comparable.

    However, two months from now, you will likely find the striped version to be faster. After all, at that point you will likely be doing multiple tasks that cause even more cache misses.

  2. Dell sells a number of RAID cards or ROMBs which use the LSI MegaRAID driver which is part of the stock 2.2.x, 2.4.x, and 2.6.x kernels. The new SAS 5 and SAS 6 non-RAID controllers use a new driver, mptsas, part of the mptfusion driver family. Both drivers are included in 2.6.x kernels, and have been backported to the RHEL3 2.4.21-x kernels.

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