eSATA vs SATA vs USB 2.0 Hard disks

I have a ThinkPad T61p Fedora 11 Linux laptop. Lately for some Linux training products we have been developing I've been doing alot of virtualization work on my laptop. Even though it has a fast dual core CPU, 8GB of RAM, and a fast internal 500GB SATA hard drive I've been seriously bottlenecked when I have a bunch of virtual machines doing lots of I/O. Some operations that normally take 20 minutes to complete have been taking 90 minutes. That is a serious productivity killer.

I need to add more hard drives and spread the I/O load across them. I would like to upgrade to a SSD drive, but I require 500GB capacity and although the just hit the market, it has several draw backs (besides the price) including using a MLC architecture. I briefly considered USB 2.0 hard drives but I knew that the USB 2.0 connection was a bottleneck

I decided to add an external eSATA hard drive using an ExpressCard eSATA controller.

Here are raw sequential I/O throughput the benchmark numbers on three drives. I tested the performance using hdparm -tT /dev/{sda,sdb,sdc}

Internal SATA SAMSUNG HM500LI 500GB
73.4 MB/sec

eSATA Western Digital WD10EVVS-63E 1TB "My DVR Expander"
85.1 MB/sec

USB 2.0 Lacie 120GB rugged
24.4 MB/sec

I used a Syba SD-PCBX-ESA2 ExpressCard SIL3132 Chipset 2x e-SATA II, 54mm. The great thing about Linux is that the controller was supported out of the box by Linux's sata_sil24 driver. I had nothing to install. I just plugged everything in and it all worked.

It would have been nice if my laptop had a built-in eSATA port. Hopefully my next Calpella platform based Thinkpad will have bottleneck free USB 3.0 ports and hopefully eSATA as well.