By: Mr Johnn
Submitted: 2009-07-13 09:57:37 | Word Count: 736
Bigfoot is the name of the hard disk marketed by Quantum Corporation in the mid 1990s. Compared to typical hard disk drives, Bigfoot drives were larger in size. They measured 5.25” wide while the typical hard drives were 3.5” in diameter. Bigfoot drives were made in this size assuming that PC users of that era already have cases that have provision for a 5.25” drive.
Quantum Bigfoot drives were characterized by lower data densities and fewer moving parts, so they were able to offer them at lower price, making them more competitive in the market. Though Bigfoot drives were lagging behind many other drives in terms of performance, they earned several OEM PCs customers, including Compaq and HP, owing to their large data capacities.
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Bigfoot drives were available in both single platter models and double platter models. Single platter drives were available in capacities of 1.28GB, 1.6GB, 2.1GB, 2.5GB whereas double platter drives were available in 3.2GB, 4.3GB, 6.4GB, 8.0GB, 10.0GB, 12.0GB, 13.0GB, and 19.2GB.
The drives communicated with the computer using ATA-3 interface. Bigfoot drives were amongst the first to support Logical Block Addressing (LBA) and Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.) monitoring.
Quantum improved the capacity of the drives over a period of time. The 19.2GB BigfootTS became the largest consumer-grade drive available at its release. However, the increased data density resulted in increased manufacturing cost, and the Bigfoot moved towards the premium price point. This resulted in poor performance in the market driven by low-cost drives. The model was discounted in the late 1990s.
WeRecoverData.com - Logical Block Addressing
Logical block addressing (LBA) is a method to address hard disk location by a single sector number rather than the cylinder-head-sector (CHS). CHS scheme did not map well to devices except hard disks. They were used in early MFM and RLL drives.
LBA was designed to support ATA/IDE drives when they reached the capacity of 504MB. Logical blocks in modern computers are typically 512 or 1024 bytes each. ISO 9660 CDs have 2048-byte blocks.
Modern computers used enhanced BIOSs to translate CHS addressing into LBA format. Enhanced BIOS achieved this by generating more virtual drive heads than the actual number of disk heads. They selected LBA mode automatically, and worked around the 1024-cylinder BIOS limit by showing the hard disk to the operating system as having half as many cylinders and twice as many heads.
SCSI used LBA as an abstraction. In more complex cases involving RAID devices and SANs where logical devices are composed via LUN virtualization and aggregation, LBAs are translated from the application’s model of the disk to that used by the actual storage device.
In second ATA standard, the LBA mode became the most commonly used scheme when communicating with ATA drives and their successors. LBA block address ATA can be 28-bit or 48-bit wide (introduced in ATA-6), which results in a disk size limit of 128 GiB or 128 PiB, respectively.
WeRecoverData.com - Zone Bit Recording
Zone bit recording (ZBR) is a method of optimizing the hard disk drives to enable more sectors per track on their outer tracks than in the inner tracks. This process is also known as zone density recording or multiple zone recording.
Hard disks are made of several disks called platters. Each platter is divided into concentric circles called tracks. These tracks are further divided into sectors. Each sector can carry a fixed number of bits. In this circular disk, as the distance from the center of the platter increases, the circumference of the tracks increases.
In earlier hard disks, each track consisted of same number of sectors and each corresponding sector had same angular measure. Because of this, the sector near the edge of the platter was longer than that near the center, so the magnetized region representing the data bits in the sectors near the edge of the platter were spaced farther than those in the center. As a result, the medium near the outside of each platter was underutilized.
Zone bit recording was introduced to equalize the physical separation between magnetized regions representing the bits. To achieve this, all sectors should have the same linear measure, not the same angular measure. Zone bit recording addresses this issue by grouping the tracks into zones. Tracks in the inner zone have the lesser number of sectors, and tracks in the outermost zone have more sectors. Thus the magnetic medium of each platter is utilized as effectively near the outside as near the inside.
