Performance Advantages of Large Caches for Mobile HDDs Investigated

Importance of Large Caches for HDDs Explained

by Yaroslav Lyssenko

[ 12/22/2005 | 08:07 PM ]

Designing hardware components for mobile computers is always a compromise. When performance is a first place priority, battery life as well as weight of the notebook, will surely be sacrificed for higher overall speed. However, there are measures that may not affect battery life dramatically, but boost performance substantially. A way to increase speed of hard disk drives (HDD), besides boosting rotation speed is to install large caches.

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Because of the requirements for lower heat dissipation and power consumption, HDDs for notebook PCs are usually spinning at 4300rpm or 5400rpm, by contrast, desktop hard drives feature 7200rpm or even 10000rpm motors. In order to compensate performance loss due to lower spinning speeds, manufacturers install larger HDD caches.

Phoronix web-site has carried out an investigation of performance dependence from HDD cache size. The author put Hitachi’s Travelstar HTS541080G9AT00 2.5” notebook hard drive with 8MB of cache against Toshiba’s Slim MK1032GAX with 16MB cache onboard. Both HDDs boast with similar specifications such as 5400rpm, ATA-6 interface, 5.5ms average latency, and 12ms average seek time. 

“The benefits we have seen today are certainly more distinguishable than what we had seen in the late 1990’s with 512k and 1024k ATA drive cache variations. Keep in mind, both hard drives were not exactly identical when it comes to the control parts but excluding the cache size and storage capacity, their seek times and remaining features were near identical although provided by different manufacturers,” the conclusion reads.

This testing had been carried out on Lenovo ThinkPad R52 notebook, powered by Intel Pentium M 750 microprocessor operating at 1.86GHz, accompanied by 512MB PC2-4200 (533MHz) DDR2 memory and ATI Mobility RADEON X300 64MB graphics chip.  

“Although there was not much variation between the two drives in some of the benchmarks, when it came to intensive Iozone and Disk Wriggler tests, the true capabilities of a 16MB cache had definitely shined. Those not looking for the disadvantages of increasing the RPM of their mobile hard drive, a greater cache size on a lower speed drive is certainly another worthy investment for users frequently away from their desktop while demanding speed,” concludes Phoronix. 

• Phoronix: Mobile HDD Cache Comparison.