sas ssd

By admin 　http://www.robertmead.net/sas-ssd/

How to Build Your Own PC - the Smart Way (Part 2)

In the previous article we looked in depth in the heart of the PC build:

The CPU (processor)

The Memory (RAM)

The motherboard (motherboard)

Now we look at the rest of the PC:

The storage subsystem (hard disk or HDD)

The graphics processor (GPU)

The Case

The cooling (heat sink and fan or HSF)

Select Design ... ... ... Standardization Tune and Build ...

The storage (hard drives)

When you save your work, run an application or game, power drive or to encrypt or otherwise required to access or permanent storage of your disk subsystem offers are limited by its performance. The storage system is almost the only mechanical system in the computer (although this is changing Now with the advent of Solid State Drives, SSD's). The data is stored on a magnetic hard disk and arranged in concentric circles around the disc from the center to the edge. If your computer to access the data on one side of the disk and then the other has the drive to physically move the head and back, and wait for the disk rotating at the right place to start reading or writing process. The time required to do this is known as latency, and the average time to head to move to a certain point and data reading is given as Average Seek Time (usually in milliseconds, ms).

Manufacturers provide spin speed and the average seek time of their data centers. In addition, all drives have an onboard memory cache that the drive for intelligent software to save previous (or read ahead) requests to read, so it can almost intelligent Get ahead of the data you want to read. The data can then be quickly retrieved without disk head movement. The other major factor in drive performance with a maximum pipe (ie bandwidth) between the CPU and the drive to ensure that once the disc has the available data can be transferred.

Our design requirements for high performance storage, in approximately this order:

High bandwidth - achieved;
- high areal density (more data packed into a smaller space can be read faster, target density is about 300 gigabits per square inch)
- a high drive speed of at least 7500rpm or better yet 10,000 or more,
- high data transfer rate of 3 Gb / s,
- and supporting the latest interface standards of SATA II or SAS (SCSI)
- a large cache on board at least 16 MB or better 32MB or more

best possible Average Seek time (to under 10ms, 5ms under extreme random access performance)

RAID (Redundant Array of Inexpensive Disks) - the use of arrays of disks working in parallel to higher speeds, higher transfer rates and to achieve redundancy for resilience in the unlikely event there is a drive failure

Most manufacturers of ordinary PCs will only quote your disk capacity in GB, and used as a selling point, they are often unable to provide you the above information and unlikely that they consider in the design. There is a balance between performance and value, but also a delicate balance between bandwidth and seek times. If the work you do is mainly sequential disk access is probably more important than fast times at high bandwidth to search (ie photography, multimedia) have. You can also consider this in the design of RAID storage arrays they affect the average seek time time, write speeds and have their own critical configuration parameters that affect how they will function effectively.

The rest of the Solid State computer has no moving parts and can operate at high speed without considerations for the physical limitations of movement or wear. With memory prices getting ever cheaper and cheaper the next logical step is for the latest mechanical device to remove from the heart of the computer and replaced by a solid state non-volatile memory or flash memory (NV-RAM). This is where the advantage of current development drive and solid state drives are now available in smaller sizes (up to 250 GB a single disc), but fast and very resilient. SSD's have some significant advantages and a few technical obstacles that make it even imperfect as a hard disk replaced worth consideration:

Pros

Random access is fast - as there is no mechanical head move to drive to spin

Resilient - very long life with no moving parts to wear and deteriorate, or suffer from stress or shock damage (an SSD can usually tolerate a shock load of more than 1000G!)

Lightweight - no motors or magnets, cylinders and disks, the SSD or a rigid chassis is very light

Lower power consumption - moving mechanical parts, generally use more power

Future roadmap - mechanical drives will probably eventually die out and replaced by the SSD technology, is currently at very early stage

Cons

Its still very expensive - usually an SSD is much more expensive than the equivalent mechanical hard drive

Write speed is generally lower than a mechanical Hard drive - because of the way data is retrieved from its NV-RAM transfer speeds currently a backlog mechanical drive. Random writes on a fragmented can drive a lot slower.

Capacity is currently limited - the main stations are only about 250GB

The technology is still maturing with different designs for mobile access (MLC / SLC) and the organization worked through the market to trade off performance for size

Marginal improvement compared with the best mechanical RAID arrays - for the same investment you could buy and configure a RAID5 array of 15K rpm SAS disks perform better than the current SSD technology

The graphics processor

Graphics processing is now so demanding that it needs at least one special processor his own, a GPU (usually resident on a onboard card). The GPU is a real workhorse, games where 3D modeling or processed. If the CPU had to perform all 3D graphics work that would quickly get bogged down because it is not optimized for it. But the CPU has an important role in determining the workload that is fed to the GPU (s) and when not balanced Performance will suffer from one or other non-job. The CPU is powerful enough to deal with GPUs and the GPU instructions must be processed quickly enough to keep moving instructions and not in line frames and truncation (ie low fps). The main manufacturers of graphics processors are ATI (AMD) and nVidia, and both are excellent graphics processors at any one time or another leads to maximum horsepower race in graphics processing.

Modern graphics processors are full height cards, which have their own food (sometimes two) and their own special cooling. They use PCI Express slots for maximum speed and can be installed in multiples to work together in parallel usually in pairs (known as an nVidia SLI or ATI Crossfire configuration). It is now possible to run three or four graphics processing systems (the latter with 2x dual processor cards).

Our own benchmarks and tests have shown that by-and-large the best value is obtained with some cards as there are a number of applications and games that are not able to make effective use of multiple GPUs. The benefits of multiple cards are non-linear to the significant linear increase in cost. Of course multiple cards remain an upgrade available route in the future. But if you want the ultimate speed and performance then Quad GPU's is definitely the way to achieve it. My advice would be your system to build around the best single card you can afford and then you have an upgrade available for multiple cards you'd like to go in the future. Like CPUs the graphics processor works best when kept cool. So if you want the ultimate going out for a better air or water cooling that will further improve their performance significantly.

Cooling the

The standard heatsinks with graphics cards, motherboards and processors are usually of relatively low quality alloy and provide sufficient cooling for more than performance. Invariably hardly even cooling for standard version, remember these things be done to aggressively reduce costs. The heat sink is important because if not enough heat away from the component quickly enough heat builds up and up until either shutdown or meltdown!

By factory default settings much margin designed to assure quality variability is a problem you should not, but if you push your system hard then you will need to think more about improving the cooling. To heat fast you have to pull a good contact with the processor at high pressure and thermal connections to the conduct of specialist heat very well and very fast. sufficient heat to move, so the not to build you a big enough heatsink with enough cooling surface (usually assisted with a ventilator).

The qualities to look in high quality heatsinks are:

a high quality pure metal, copper or aluminum construction with good heat conductive properties

mechanically perfect flat surface for good contact with the component

a large area over which heat can be exchanged with the air (or water in the event of a water-block)

a rapid transfer of heat from the component surface to the cooling fins usually by using special tubes heat conduction (or in the case of water a high current, high water head and half inch diameter hose)

specialized pure silver based thermal compounds that improve the thermal interface between the component and heat sink

specially designed fans with aerodynamic fins that are designed to move much air at low rpm, the most chilling with the least noise

remember a very good air cooling system is so good that many of the poorer they can exceed water cooling systems. Not always of water is better ...

The case

One good thing is often seen as a nice to have but one thing is Another vitally important component in the holistic design of a high performance system. You should look to ensure:

there is adequate circulation of air through the system (usually from front to back, from bottom to top) and the volume of the airflow is adequate. Well-designed cases are thermal zone regions, so that warm air from one component does not "pollute" to another already heated air

should the appropriate number of fans in the right places moving the right amount of air. Often 'flashy' cases, powerful fans with LED's lit so they look impressive, but they actually go very little air, and not coated on the hot spots in the PC as the graphics card and CPU

Did you know that as the air warms up in the PC case volume to increase by much as 3:1, in other words, for optimum cooling you need three times the volume of air from the case and shift, some designs take account of that. Piping in race engines and exhaust is specifically designed around this principle so why you see a small hole on the front to let air in and a much larger hole on the back

A case made of solid aluminum not pressed steel, and anodized instead of painted, much more sustainable for upgrades, maintenance and parts changes and inspections. Solid well built cases to make less noise, how often have you been a computer developing an annoying rattle ...

A well-designed case to allow easy access to all components so they can be installed and removed without placing stress or risk of damage to the system, or engineer!

Some cases are designed to easily accommodate large heatsinks, full length graphics cards, large power supplies, disk arrays, radiators, pumps, reservoirs and pipes of the cooling water, ensure you fit for purpose

Last but not least one case, a feast for your eyes. There are a lot of flashy looking cases there would I do not want in my house, and some nice unobtrusive classic designs that I would, but that is your personal choice ...

3.5 SAS Tray Caddy Sled Dell G302d F238f R710 T610

$17.99

Dell F9541 3.5" SAS SATA Tray Caddy NF467 H9122 G9146

Description
Dell tray / caddy - for SAS / Serial SCSI / SATA Hard Drives

Part Number
F9541 / NF467 / H9122 / G9146 /
MF666 / D981C / 0D981C / Y973C / 0Y973C / J105C

Compatible Models
Dell PowerEdge 840, 1900, 1950, 1950 III, 2900, 2900 III, 2950, 2950 III, 2970, 6900, 6950, R300, R900, R905, T300, T605 Servers

DELL PowerVault M...

HighPoint RocketRAID 2720SGL 8-Port PCI-Express 2.0 x8 SAS/SATA RAID Controller

$156.93

Highpoint Technologies RocketRAID 2720SGL SAS RAID Controller - Serial ATA/600, Serial Attached SCSI - PCI Express 2.0 x8 - Plug-in Card ROKCETRAID2720SGL Hard Drive & RAID Controllers...

Seagate Constellation ES 1 TB 7200RPM SATA 2.0 3Gb/s 32 MB Cache 3.5 Inch Internal Hard Drive ST31000524NS - Bare Drive

$191.44

Constellation ES - High-capacity storage designed for seamless enterprise integration...