Adobe Photoshop CS5 for Photographers - Martin Evening [63]
Internal RAID
You can fit an internal RAID system with a do-it-yourself kit consisting of two internally mounted drives and a RAID controller card. This should not be too challenging to install yourself, but if you are in any doubt about whether you are capable of doing this then you should get a qualified computer specialist to install such a system on your computer. The advantage of an internal RAID is that it is always there whenever you turn the computer on, and is an economical solution compared with buying an external RAID drive setup. Most PC tower computer systems should have plenty of free hard drive bays, which will make it fairly easy for you to install internal RAID. An internal RAID setup will definitely speed up the time it takes Photoshop to read and write data to the scratch disk. However, if you have more hard drives running simultaneously this will mean more power consumption, which in turn can generate extra heat and possibly more noise too. Be warned that this heat may cause problems for the cooling system in your computer and put extra strain on the internal power supply unit.
OpenGL video cards
OpenGL-enabled video cards are able to offload processor-intensive activity from the CPU to the video card's GPU (Graphics Processing Unit). An OpenGL card also uses its own on-board RAM to lessen the burden on the CPU and this results in faster overall video performance.
External RAID
External RAID hard drive units (Figure 2.21) are not overly expensive and you can easily buy a ready assembled bay dock with a couple of drives and a built-in RAID controller that can be configured for RAID 0. The speed will be governed not just by the number of drives making up the RAID but also by the speed of the cable connection. Most RAID systems these days will connect to the computer via a FireWire 400/800 or SATA connection, which may again require a special card in order to connect to the computer (for now). At the time of writing it seems that computers in the future are more likely to support SATA as standard. My own personal experience has led me to be rather wary of relying on SATA. I have had two SATA RAID units fail or have problems maintaining a connection to the computer. For this reason I have chosen to stick with FireWire 800, and even this I find isn't completely reliable on the Mac OS X system.
Figure 2.21 A RAID system drive setup contains two or more drives linked together that can provide either faster disk access or more secure data backup.
GPU settings
Photoshop is able to detect the graphics card used by your computer and whether it has a built-in Graphics Processor Unit (GPU) capability. If so, you can then check the ‘Enable OpenGL Drawing’ option to make full use of the graphics processor memory on the GPU enabled graphics card. As was explained earlier, in Chapter 1, this preference setting affects images opened in Photoshop on a per-window document basis.
The main advantages of enabling OpenGL are: smooth views when using odd number viewing percentages, image rotation, flick panning, smooth animated zooms, the bird's-eye view zoom-out feature plus pixel grid display at view magnifications greater than 500%. Note that OpenGL is only available on later operating systems, which are basically the ones that are required anyway to run Photoshop CS5.
Clicking the Advanced Settings… button opens the OpenGL settings dialog shown in Figure 2.22. If you know what you are doing you can adjust these to gain the best performance from your particular OpenGL-enabled video card.
Figure 2.22 The advanced OpenGL settings dialog.
Cache pyramid structure
If you have OpenGL switched off, or your video card does not support OpenGL, you may sometimes notice how layered Photoshop images are not always displayed with complete accuracy at anything other than the 100%