How fast is your disk ? There are several kinds of hard dives on market today (ide, sata and now ssd) but the most unknown’s one is the gigabyte i-ram (you should go on ebay to find one, it’s the only way to grab this marvelous hard drive).i-RAM acts like a regular SATA hard drive but utilizing conventional DDR memory modules.
gigabyte I-ram
For measuring the speed of your disk the two most important things are sequential access (when you’re reading or writing disk blocks) and random access (where you access your disk at random. In that case the disk head moves rapidly from one place to another). Random access is the most important one, in case of booting time process for example, you have to load a bunch of small files, so your disk head has to access them as fast as possible.
On linux you could find a little tool called hdparm to measure sequential disk performance.
Measuring your first sata disk like this : sudo hdparm -t /dev/sda1
in my case (two hard drives in raid0) :sudo hdparm -t /dev/md0
Timing buffered disk reads: 342 MB in 3.00 seconds = 113.92 MB/sec
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For measuring random access time there are no native tool, you have to compile this one (called seeker)
wget http://www.linuxinsight.com/files/seeker.c
gcc -O2 seeker.c -o seeker
sudo ./seeker /dev/md0
Results: 119 seeks/second, 8.34 ms random access time 
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Now comes the insane benchmark of the King :
sudo hdparm -t /dev/sda1
/dev/sda1:
Timing buffered disk reads: 346 MB in 3.01 seconds = 114.87 MB/sec
sudo seeker /dev/sda1
Benchmarking /dev/sda1 [4094MB], wait 30 seconds…………………………
Results: 13266 seeks/second, 0.08 ms random access time
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And if you don’t like numbers, and measuring tools, watch this relevant video (windows booting time on iram) :
for linux example, on ubuntu 8.04 i have a 14 seconds result on ext2 filesystem with bootchart.
