hard disk : Computer Hardware Buyers’ Glossary

Understanding the Specifications

The main specification is the capacity in gigabytes, or billions of characters. 1 gigabyte is equivalent to about 2 CDs full of information. The main reason you need a large hard disk is if you cache CDs on your hard drive, collect mp3 music, or pornographic images or games with huge sets of background images or animations.

Little mechanical arms sweep over the rotating magnetic disk surfaces inside the disk. The faster they can move to get to the data you want, the more responsive the disk. The time it takes to traverse 1/3 the distance from outer edge to innermost track is called the average seek time. The smaller this number is, the better. Typical seek times might be 7 milliseconds.

Once the seek is complete, you still have to wait for the data you want to spin around under the read heads. The higher the RPM Revolutions Per Minute) and the faster it will get to the data you want and the better the sustained transfer rate, Good drives are 7200 RPM, economy ones 5400.

The more cache memory is the drive the faster it will run. Good drives would have around 8 MB, economy ones about 2 MB. Fluid bearings will make the drive quieter. The higher the rated transfer rate the better. ATA 100 = 100 megabytes per second transfer rate, ATA 66 = 66 MB/sec, ULTRASYNC 33 = 33 MB/sec. SATA (ATA150) is 150 megabytes per second. The smaller the seek time the better, good drives are under 4 milliseconds average access time. Economy drives come in around 10 ms.

SATA and RAID

RAID comes in several levels: 0, 1, 2, 3, 4, 5, 6, 7, 10, 53 and 0+1. For home use, you are probably only interested in levels 0 (speed) or 1 (safety).

With a SATA drive, you need a SATA-capable, RAID-capable motherboard or add-on PCI SATA controller. You can also use SATA on a single disk without RAID. The SATA option will add about $60.00 CAD to the cost of the motherboard, and about $50.00 CAD to the cost of a drive. Of course, for RAID, you have the added expense of twice as many drives.

Installing a New Drive

You must divide the drive into partitions e.g. C: D: E:. I find it wise to use a small C: partition with mainly just Windows on it and apps that insist on C:. If it does south it does not take all your data with it. You can easily Norton Ghost it in its entirely easily if it is not too big. Avoid Dynamic Disk partitioning. For optimal speed, just pad out each partition with a little growing room, and leave all your free space unassigned at the end. You can use PartitionMagic to shuffle partitions later to add free space into whichever one needs it.

If you add a new hard disk or change your partitions, sometimes all hell will break loose because Windows or NT will reassign the drive letters of the existing partitions. All your software will stop working. Read up on how drive letters are assigned at Microsoft Not to panic! First use PartitionMagic or similar tool that is self-booting to select the correct partition for booting. Then once you have booted NT/windows 2000, you can use the start ⇒ programs ⇒ administrative tools ⇒ Disk Admistrator ⇒ Tools ⇒ Assign Drive Letter to put the drive letters back the way they used to be. Repair the drive assignments before you do anything else! Don’t install any new software until you have the drive letter assignments repaired.

If you are using Windows 95/98/ME, I think you are S.O.L. If anyone knows a fix, please let me know.

Don’t reassign new drive letters to existing partitions. If you do, any software on them will stop working. There are reputedly tools that will let you do this and fix the registry to track the new assignments, but that is a bit like doing brain surgery with a Swiss Army knife. These tools reputedly can also move applications from partition to partition.

You should not change the partition that you boot a NT/Windows 2000 from. If you do you, will create a new registry on that partition. It will know nothing about the apps you have already installed. They are recorded in the registry on the old boot partition. Very clever people know how to transplant information between registries, but this is tricky and not for the faint of heart.

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