Conventional Hard Disk Drive Sermon
Courtesy Wiki Image
Hard Drive Form Factor
- Desktop – 3.5” form factor – Speeds vary
- Laptop – 2.5” form factor – Speeds vary
- Enterprise / Server – 3.5” form factor usually with 10,000 RPM speeds with SCSI or SATA connections. These drives are typically used only for server backplanes and usually not in a home consumer environment. Some hard drives like the WD VelociRaptor series are actually 2.5” drives encased in an aluminum heat sink. I have a 300GB model and they are now affordable.
- AKA IDE/EIDE by WD, Seagate and others were PATA, eventually also called Ultra ATA
- Two devices on one ribbon of 80 wires (40 each device) with 18” length max
- If you had two devices on one ribbon you had to designate one as a master (devices 0 and 1)
- Connections were different for laptop drives and desktops
- Four devices max per standard PATA controller
- Four pin Molex type power connection +5 (red) and +12 volt (yellow) wires
- ATA-6 (the last mainstream adopted spec) is at 1 Gbit/s – PATA drives are just old technology.
- 7 wires with one meter max length
- Connections are the same on laptops and desktop drives
- One cable per drive
- Fifteen pin power with +3, +5 and +12v
- SATA provides NCQ (Native Command Queuing) if both the controller/chipset and the hard drive support it. Now think of a record player again, if you tell your drive you want to get songs 4, 8, 2 and 1, NCQ will read the songs 1, 2, 4 and 8 based on the location of the data. Not the best analogy of course but I hope you get the idea. Just think of NCQ as a 10% performance boost in your system.
Drive Advanced Formatting
Realistic Drive Performance
Serial Advanced Technology Attachment Spec
- Version 1.0: SATA 1.5Gb/s - Initial interface speed for 150MB/s data transfer rate
- Version 2.0: SATA 3Gb/s - Enhanced interface speed for 300MB/s data transfer rate, backward compatible
- Version 3.0: SATA 6Gb/s - Most recent interface speed increase providing 600MB/s data transfers and backward compatibility
Power Consumption and Sound
Sound could also be a factor. More RPMs means more sound. In addition, desktop drives usually make more noise than laptop drives.
For a great list of Hard Drive sound reduction products, check out FrozenCPU!
Conclusion – Overall Drive Performance
- Using sustained transfer rates for comparison is good if you are going to use your drive for massive storage and file transfers but may not be indicative of your actual performance
- Latency figures should all be about the same for each RPMs category so watch them
- Random read and seek times are a great way to see how daily usage will be affected
- I/O data transfer times are theoretical and nowhere near realistic – Overhead
- If power is important then compare watt ratings
- If sound is important the check the dB ratings
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