In episode #24 of the BYOB podcast we discussed traditional hard drives in detail. Read on for an overview of the subject and some great information on hard drive specifications.
BYOB Podcast #24
http://homeservershow.com/byob-episode-24.html
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Conventional Hard Disk Drive Sermon
Since 1956, the hard drive has gone from a mere 3.75 MB to 3.0 TB, and shows no sign of slowing down any time soon.
My Favorite Drives
Mass storage hard drives have changed over the years but the basic concepts still hold true for these spindle type hard drives. A spinning platter with a head that reads and writes data is the norm.
Some hard drives may have more than one platter, so think almost of a record player with multiple records on the turntable.
Image Courtesy of Wikimedia
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Hard Drive Form Factor
There are three mainstream types of hard drive form factors. These drive types are:
- 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.
Connection Types
There are two basic consumer types of hard drives. There are the older Parallel ATA drives and the newer Serial ATA drives. We call them PATA and SATA. Lets briefly review each one.
PATA
- 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 drives 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.
PATA desktop and laptop drive
SATA
- 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.
Jumper in use on WD Advanced Format SATA drive used in Windows Home Server
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Wires
Red new. Grey old. Need I say more?
How about an article on managing Basic and Dynamic drives physically and through configurations on WHS Vail. Currently have three satas with something wrong on PHY3/Disk 3. Cannot understand the arrangements WHS has undertaken. Seems to have a mind of it's own.
Vail uses a different file management system and the drive data is not useable outside of Vail. The current beta of Vail includes Drive Extender technology but has since been announced as being removed from Vail. Once a new Vail Beta build is released (maybe next year?) then we will address the drive management. In the current release you should be able to remove the drive and replace it with another. I would then run a utility or chkdsk on it to see if Vail was teh issue or the drive itself.
BACKUP ANY DATA BEFORE REMOVING A DRIVE.