Choosing a Hard Disk Drive or a Solid State Drive for your computer internal drive or as external back up?
Hard Disk Drives (HDD) are just round platters with a magnetic coating that spin at a very fast speed. This is the same magnetic material on video tapes and audio tapes. The heads that read the magnetic material are flying on a cushion of air caused by the spinning platter. The heads move in and out of the physical platter reading the ones and zeros.
The weakest link in electronics is where electronics meets mechanics. These electromechanical devices are prone to failure and they wear out because they are subject to constant movement. Solid State Drives (SSD) have no moving parts to wear out and are not by design subject to mechanical failure. However these SSD devices electronic components do and will wear out. The main advantage of SSDs over the mechanical devices is speed.
Some technical background:
Until Drive standards evolved the only specification was named after the first hard drive ST-506 ( 5megabyte hard drive ). ATA (Advanced Technology Attachment) also know as AT attachment later called Parallel ATA or PATA was a standard interface for hard ddrives and Optical drives. Designed by Western Digital in 1986. Evolved from WD Integrated Drive Electronics or IDE. When Serial ATA came out in 2003 ATA was renamed PATA.
Originally the 40 pin configuration had a length limitation of 18 inches, it was limited to internal use. the Parallel interface allowed 16 bits at a time to be transmitted through the cable. Originally 16 MBps later 33, 66, and finally 133MBps. The faster speeds cause crosstalk between the data lines and the ribbon cable was modified to 80 pins. The added wires were grounded to eliminate the noise problems caused by data speed. The higher speeds were called UDMA or UltraDirect Memory Access, UDMA 4, 5 and 6 were for 33, 66, and 133 MBps configurations.
Devices with removable media required and Eject command which was not part of the ATA specificatyion. So a group called the Small Form Factor committee (SFF) defined the ATAPI Protocol or ATA Packet Interface.
To accommodate multiple devices on one cable a device 0 and device 1 jumper was set on on the disk drive. Cable select was also available. by looking for the first host to ground pin 28, that device became the master while the second became a slave. No longer called master slave they are generally referred to a device 0 or device 1. The order in which to BIOS sees the devices.
SATA or Serial ATA was developed for speed. While it is true more data can pass through parallel, it’s days were numbered since speed through a serial cable can be sent at extremely higher rates.
SATA languished in the early days of its development. Until the advent of Solid State Drives or SSDs. Early SSDs utilized RAM (1950-1993) or Flash Memory (1994-2012). They were still to costly for the average user. Most SSDs use NAND Flash memory. It’s Cost efficiency has brought the prices down and popularity is taking off. NAND however, has it’s limitations and life expectancy. Manufacturers won’t reveal the life expectancy of the NAND technology. It is safe to say it is “cost driven”. To solve this problem SSD makers have a huge amount of spare Memory locations they can remap to if a location should go bad. Because the quality can be determined by the amount of spare NAND memory a device has, the builder is reluctant to relesase those SSDs specifications. De-fragmenting a drive and secure deletion can shorten the life of a SSD therefore more complex deletions and a TRIM command “zeros out” a whole deleted file. Wear leveling also means that the physical address of the data and the address exposed to the operating system are different. (That’s the biggest problem with SSDs wearing out.) The Trim command is supported in Windows 7 and 8. Apple supports TRIM in Mac OS X versions since 10.6.8 but only with Apple purchased Drives.
Windows 7 and 8 both utilize the TRIM command in and can be turned off in the registry.
So now with SSDs SATA is evolving. Revision 1 was 150MBps. Revision 2 was 3 GBps and Revision 3 was 6 GBps. This quickly became the standard. With the possibility of 12GBps in Revision4 .
Also connection to the PCI-Express Bus allows 8GBps with the possibility of 16 Lanes. This is already in the revision 3 Specification.
AHCI is the software used to control SSDs and developed by Intel. The industry is just barely waking up to its’ existence. All the while, Intel is working on NVM Express which would allows 64,000 queues with 64,000 commands each, simultaneously. Although not released Yet..
With the ST506 Interface Western Digital had the market with the famous WA2 board. With two cables, one for data and one for control. This was do to the fact that the drive was basically a dumb device and needed control. The WA2 board, gave the end user total control over the drive. The recording format for the magnetic media was called MFM for modified Frequency Modulation. This was how the write head was controlled. Now here come the Benchmark Wars. With that much control. Benchmarks could measure data transfer rate, track to track seek time, long seek and Real Low-Level formatting. There wasn’t anything hidden. The Benchmarks left the Major players constantly trying to outrun each other. So when Western Digital suggested that the WA2 board be placed on the hard drive. (for better performance of course. Never mind the fact that the end user had virtually no control over the hard drive). Thus called IDE for Integrated Drive Electronics. Then came along RLL, or Run Length Limited or 2,7. Developed by IBM This recording technique replaced MFM with RLL and compress 50% more data into the same space. A 20Meg drive becomes 30, a 40meg becomes 50 and so on. This increase in densities posed a problem. The media needed to be certified for RLL or data errors would or could occur. The certified drives cost more. Unscrupulous build would buy the cheaper drives and sell them with RLL. IDE changed all that. Embedded on the drive was every trick in the book to make the drive appear to run faster, rendering benchmarks almost obsolete. To improve data transfer, Cache was added. Just how much was not always disclosed. RLL was implemented also. Then came Enhanced IDE. These included most of the features of the forthcoming ATA-2 specification and several additional enhancements. Other manufacturers introduced their own variations of ATA-1 such as “Fast ATA”. Drive capacities have increase significantly since those days
So where does SATA fit in. Most people place there OS on the SSDs (which utilize SATA) and a few other Games that are I/O dependant. Others use three SATA drives for a RAID (Redundant Array of Independent Disks), a system of multiple hard drives for sharing or replicating data so no data gets lost if you have a drive failure. Upgrading your regular old hard drive to a solid-state drive is one of the best upgrades you can make to your computer nowadays, as our hard drives tend to be among the biggest bottlenecks in performance. SSD read times are insanely fast, meaning using one will make your boot times and application launches super short.
