A hard disk drive is the slowest component in your PC. While SSDs are freakishly expense (the G.Skill Falcon SSD 64GB costs around R2600) they do vastly improve the performance of the PC equation. But is price the only reason people aren’t more interested in them, or do people just not care about HDD performance? I did a huge poll (among 5 of my friends) and found that most people would always choose extra capacity over extra performance.

Well, what can you do if you want extra performance but aren’t willing to shell out the R2600 for a G.Skill Falcon? What you can do, is get yourself a Western Digital Black drive. I recently bought the 750gig version, which costs around R200 more than a 7200.12 1TB from Seagate. Or, for a little less than the price of the 1.5TB Seagate drive, you could buy a 1TB WD Black. Is it worth it losing 500 gigs of space for better performance? I’d say so. A faster hard drive will make your operating system boot up and shut down faster as well as making your games load faster.

Once you go black, you don't go back.

Anandtech did a nice preview of the Seagate Barracuda XT 2TB: SATA 6Gb/s versus the WD 2TB Black drive. In four out of the six tests performed, the WD black drive was faster than the Seagate. The WD drive was between 3% and 28% faster, while in the two tests that the Seagate was faster, it was only between 3% and 7% faster.

Another way to get better HDD performance is enabling AHCI (Advanced Host Controller Interface) mode in the BIOS, but bear in mind that only Vista and Windows 7 have native support for AHCI mode. For Windows XP, you will have to slipstream the AHCI driver in. AHCI mode enables features such as hot-plugging and native command queuing (NCQ), which allows your hard drive to rearrange the requests for best performance. Much like if you and two friends had to get on an elevator and push the floors 3,12 and 6, it would be terribly inefficient for the elevator to travel to floor 3 then 12 then 6. NCQ allows the drive to rearrange write/read commands that are transmitted randomly in order to optimize the movement of the drive heads. So going back to the elevator example, the requests will be rearranged so that the elevator goes to floor 3 then 6 then 12. On average, AHCI mode improves performance by about 5%.

According to JEDEC specifications, MLC NAND flash can perform 10 000 writes before it starts to fail; SLC can perform around 100 000 writes. There’s no need to worry, however. If you have a 256GB MLC solid state drive, and copied around 7 gigs of data to the drive every day, it would take around 360 000 days – or 986 years – before each page has been written to 10 000 times, thanks to some clever wear levelling algorithms that get incorporated into SSDs. Each page on the SSD will get written to first, before the first page gets erased and re-written.

As explained previously, an SSD will get slower due to the pages filling with valid and invalid data. It is possible for a person to claim back performance by performing a secure erase using a tool like HDD ERASE – it will free every page on the drive giving you back your performance. And if you don’t feel like losing all your data, you can use Indilinx’s Wiper Tool.

OCZ’s Solid 2 uses 34nm Intel flash with an Indilinx controller.

A TRIM is as good as a holiday

What TRIM does is take the delete process one step further. Instead of the delete command ending with the OS, the command goes through to the SSD and the pointers to the data get deleted. So while the data is actually still there, you’ve told your SSD that you no longer care about it. The tool queries the OS for available LBAs, then commands your SSD to TRIM those LBAs, giving you a drive that’s virtually “as good as new”.  At the moment Windows 7 is the only Microsoft OS that supports TRIM. After Windows 7 launches (22/10/09), most SSD manufacturers intend to release TRIM-supporting firmware for their drives.

Indilinx is actually the first to officially support the ATA8-ACS2 TRIM command. Most new Indilinx-based SSDs have a 4KB random write speed of around 13.1MB/s; without TRIM support the 4KB random write speed drops to around 6.93. Once no longer new, with TRIM, you get around 12.9MB/s. For comparison, a conventional hard disk will sport speeds of around 0.3MB/s – 0.7MB/s.

OCZ’s Agility uses an Indilinx controller with either Intel 50nm flash or 40nm Toshiba flash.

JMicron controllers suck…

…and it’s all thanks to small file write latencies. The JMicron JMF602 controller suffers from slight stuttering. Your PC will pause for anywhere up to a second, then carry on as per normal. Even with JMicron’s updated JMF602B (with double the onboard cache) stuttering is still prominent. Average latencies are in the 500ms range – that’s around 100 times slower than your average desktop drive. Some manufacturers have put two JMF602B controllers in RAID configuration, to help bring average write latencies down to around 300ms, which is still far higher than Intel’s and Indilinx’s Barefoot controllers that have a 4KB write latency of 0.22ms and 0.34ms, respectively.

While not as bad, Samsung’s RBB controller is also lagging behind the cheaper Indilinx controller with regards to performance. While new 4KB random write performance may be 3x that of Western Digital’s VelociRaptor range, once each page has been written to, its performance drops even more. It’s just not worth it, especially when you take into account that the firmware isn’t user upgradeable.

Did you know that the main performance bottleneck in your PC is your hard drive? The hard drive is the one component that hasn’t seen any fundamental changes since it was first introduced in 1956 by IBM, and is long overdue for a replacement.

Enter the Solid State Disk (SSD). Providing sub-1ms access times, it brings performance that no standard hard drive ever could. SSDs are completely silent, require far less electricity to operate and, as they have no moving parts, are more reliable. An SSD will likely be the most meaningful PC component upgrade you will ever make.

Let’s first take a look at what makes a Hard Disk Drive slow. An HDD has 1-5 platters with a read and write head per platter. These platters are spinning discs with a thin layer of ferromagnetic material, usually 10-20nm in thickness. The write head magnetizes the material directionally to represent a “1″ or a “0″. The platters typically spin at between 5400rpm and 15000rpm, 5400rpm being common for laptop hard drives and 7200rpm being common for desktop hard drives. They have a random write speed of about 1.2 MB/s, and a sequential write speed of around 80MB/s – 100MB/s. Sequential read speeds are around 80MB/s – 100 MB/s when the drive is new, and at 10000rpm random access times are around 7ms.

The fastest SSDs have an access time of around 0.11ms, and random write speeds going as high as 31.7 MB/s. Sequential write speeds on some models are as high as 240MB/s and read speeds are faster as well at around 260 MB/s, close to the limit of the SATA II specification.

SSDs do lose performance over time as well, due to the fundamental way in which NAND flash works. 1 or 2 bits of data are stored per cell (1bit for SLC and 2bits for MLC), cells are grouped into pages, being the smallest readable/writeable structure in a SSD, with 4KB pages being common today. Pages are grouped together into blocks, with usually 128 pages per block. A block is the smallest structure that can be erased in a NAND-flash device,  so while you can read from and write to a page, you can only erase a block. This is where the problem lies.

For example, if you have a block with 384KB of data and delete 128KB, as with with hard disk drives, the data doesn’t get deleted, the OS marks it as invalid. So, to the OS you have 256KB “free” space while in actual fact there’s only 128KB free in that block (256KB valid data and 128 invalid data). Now if you try to save 256KB of data to that block, the initial 256KB of valid data needs to be copied to memory(or local cache if the SSD supports it), the whole block erased, then the 512KB of data written to the block. Even while taking this delay into account, SSDs are still significantly faster than standard hard disks.

In part 2 we’ll look at the SSDs available in the South African market, how you can claim back lost performance, and why you shouldn’t purchase a SSD with a JMicron controller.