Interface Types and Performance

[DigitalJ]

When looking for a HD there's a lot of choices....sat-150, sata-300, sata 2, 8MB buffer, 16MB buffer, spindle speed, and what not.

Are there any HD experts out there who can make sense of the best all around performance/price/capacity issues? HD's with higher spindle speeds generally have a low capacity, but are they quick enough to be worth it? How much does buffer matter? And does the 3gb/s transfer rate that sata 2 boasts make them comparable to the 10k rpm drives?

I havn't seen a whole lot of benchmarking between these various types of drives, and I'm far more interested in the performance than I am the specs. Any ideas?

Thanks in advance!

[Paul Komski]

I have been using 10,000 rpm 37GB WD Sata Raptors for 18 months and have more recently installed a number of 7,200 rpm Samsung 80-180 GB Sata Drives. All were Sata 1 drives or Sata 2 drives on a Sata 1 mobo.

No benchmarking and my opinions are completely anecdotal. The biggest noticeable effects have been (1) on sustained transfers of data - whether imaging from without windows or copying files from partition to partition within windows and (2) on boot-up times (all systems using WinXP home or pro and 512 to 1024 DDR RAM). In general such sustained data transfers of large amounts of data have been in the 1GB per minute area - with the Raptors probably shading it. Possibly a full Sata 2 system would make a noticeable difference. All I will say is that the change from 7200 PATA to 10000 SATA was quite dramatic.

Others claim that a large buffer is important but I havent ever seen it take my breath away.

Lots of RAM, DMA and fast spindle SATAs are what rock for me! ;)

[saphalline]

Here's a basic rundown of features:

SATA vs PATA (aka ATA, aka IDE) - The old PATA interface is capable of burst speeds from 33MB/s to 133MB/s. While the IDE connection continues to live on for optical drives (because they don't have much more speed than 33) and older hard drives, the push for newer systems is to get rid of PATA within the next year. The interface itself is based on an old bus architecture that's 32-bit parallel and operates at up to 33MHz. Several limitations in the length of the cables and the device protocols led to the development of SATA.

SATA has several advantages over PATA, not the least of which is the end of the master/slave days. SATA has a nice simple architecture of one device per port, and of course SATA ports themselves are quite small. SATA is also a serial architecture with speeds of 1500MHz (1500Mb/s) and 3000MHz (3000Mb/s) with more headroom still available. SATA 1.0 is the 1500 version, and SATA 2.0 is the 3000 version. In addition, the SATA 2.0 spec has native NCQ and staggered drive spin-up (etc) over the barebones SATA 1.0 spec (which was kept simple to encourage adoption).

Hard drive features - The most prominent myth about hard drives is that a SATA II hard drive is three times as fast as an ATA/100 hard drive. This is not true. Simply increasing the max bandwidth doesn't make the hard drives any faster. There is no hard drive on the planet in mass production that can come close to the 3000Mb/s max of SATA 2.0. Most hard drives these days can hit sustained transfer rates of about 50-60MB/s and can burst at around 120-140MB/s. This is far below even SATA 1.0! Even the vaunted Raptors are only about 10-20% faster than this (which is still pretty good).

So what are the most important features to performance? If I had to list them in order of most important to least important, they would be: spindle speed, areal density, platter arrangement, drive mechanics, drive electronics, and buffer size. This gives you an idea of how to rate a hard drive, but there is no set formula. Even so, when shopping for a hard drive, you'll have a better idea of what to look for.