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 Post subject: Some ICH5R HDTach results
PostPosted: Sun Apr 23, 2006 1:48 pm 
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Intel's ICH5R has two modes: Compatability and Enhanced. In compatability mode the two SATA ports are set to run as slave and master on single IDE channel and share the singla channel's 150MB/s bandwidth. This setting allows compatability with Windows ME and earlier, hence its name. In Enhanced mode each port has its own IDE channel at 150 MB/s. However, HDTach reveals that bandwidth is lower than expected when using both channels simultaneously.

The first image is HDTach running on a single i-RAM with the ICH5R set to Enhanced mode. The result is the same for single drive testing in Compatability mode so no results are shown for that test. Results are ~130+ MB/s.

Single drive - Enhanced.

One thing to note is the nice flat line. The ICH5R produces continuously consistant read rates. They don't fluctuate. Compare that to two i-RAMs run as a RAID set in a PCI raid card:

Dual drive - PCI RAID.

As the first test shows a flat line we know the i-RAM produces consistant results so this test shows the RAID card probably competing for bandwidth with other hardware on the PCI bus. A nice plus for the ICH5R. As expected the PCI bus doesn't offer as much bandwidth as the ICH5R so the average read drops to ~115 MB/s.

The next test is running dual instances of HDTach. Each instance is set to test a different i-RAM, with each i-RAM running on the ICH5R. The ICH5R is set in Compatability mode. The first HDTach is started and then the second HDTach is started about a second or two later. Lining up the test result windows just right shows bandwidth results with just one test running, then two, then one again. The impact on total throughput with both drives being accessed can be seen.

Dual drive - ICH5R in Compatability mode.

We see slight fluctualtions, but the single channel bandwidth is not reduced when two drives are being accessed simultaneously. Total combined bandwidth is still about 130+ MB/s. You may also notice that random access time jumps to 0.5ms. Though still very good compared to a typical hard drive, this delay is caused by the chipset as a single drive access time is to low to be measured by HDTach. This is in contrast to what we see in the next test - Enhanced mode. Everything is the same as the previous test, except that the ICH5R is switched to Enhanced mode.

Dual drive - ICH5R in Enhanced mode.

Again we see slight fluctuations while both tests are running, but more importantly we see that total bandwidth is lower than expected while both drives are being accessed simultaneously. A single drive will produce about 130 MB/s. If everything was linear, we'd expect two drives on independent channels to produce about 260 Mb/s. But instead we see a total combined bandwidth of about 225 MB/s - likely the upper limit of the ICH5R SATA controller. To the ICH5R's credit, access time isn't affected nearly as much in Enhanced mode, becoming just measurable at 0.1ms.

The ICH5R wont run the i-RAMS in RAID so tests are limited to the above.


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PostPosted: Sun Apr 23, 2006 5:36 pm 
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Very interesting test results. I wish normal Hdd will have steady read rate like that - probably have to wait for solid-state Hdd or go for i-RAMs now. :D

*seriously considering......*


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PostPosted: Sun Apr 23, 2006 6:23 pm 
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I know what you mean. Going to the other extreme is my notebook drive. Very quiet and reliable, but....

Samsung

I'd like to see a motherboard that piped PCIe lanes to an onboard controller that was connected to eight DDR2 800 DIMM slots. Sweet!! I bet it would sell like wildfire provided it had good feature sets and allowed you to populate it with as little or as much RAM as you needed.


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