Many of you will have seen this in your motherboard manual. Its usage is is primirally to safeguard data and also has in
most cases the secondary effect of speeding up data transfer.
The expression "fault tolerance" is often seen, it is a measure of the safety of your data should one of your hard drives
become faulty.
Most motherboards have these Raid types, 0, 1, 0+1 or 1+0.
There are other RAID sets that need not concern the average user as they are normally found on database servers etc.
RAID 0
This is for people who prefer speed over safety, the fault tolerence is 0, if one of your drives goes faulty you have
lost the lot. In an example with 2 drives of say 100GB each your total capacity will be 200GB and the files will be
split during storage across both drives. When being read back the file is read from both drives thus giving an excellent
speed increase, this is known as "striping".
RAID 1
Again with the same 2 drives your capacity will be 100GB as one drive will be an exact copy of the other thus slowing
down on the write side of things but giving a slight speed increase on the read speed. This is known as mirroring.
A failed drive is simply replaced and copied.
RAID 0+1
This needs 4 drives as a minimum. This is the mirroring of two striped pairs, if one drive fails and is not immediately
replaced the system runs essentialy as a Raid 0.
RAID 1+0 (a.k.a RAID10)
The reverse of the above, the striping of two or more mirrored pairs, mathematically more secure, depending on which
drives fail the system will continue in safe mode.
Dual Core Processors
What are they ?
Two processors built into the same chip
Why bother ?
Speed increases over 3GHZ were causing cooling problems and high power usage.
Are they twice as fast ?
No, programmes need to be multithreading to use dual cores.
Multithreading ?
Put simply the programme has to be specially written to take advantage of the two cores by using one core for say audio and the other for video at the same time.
Are there many of these programmes ?
No and what there are will be expensive.
So these multithreadings run twice as fast ?
Once again no, firstly they have sort out which thread is to be sent to which processor, secondly there is a high speed memory cache on the chip running far faster than normal memory, unfortunately both cores share the same cache so one core has to wait for the other core to finish and pass it back.They also share access to the system bus and that´s another holdup.
Is there any upside ?
Yes the cores are more efficient than previous processors. Multi tasking is vastly improved as the operating system thinks it has two seperate processors it will run say a CD burning programme through one core and a video editor through another. You have better cooling and less power usage.
There seem to be a lot of thes dual core chips, which is which ?
Here we go
Core Duo
Intel´s first effort made for portables (32 bit).The "T" in the model number signifies 31 watts, the "L" 15 watts and the "U" 9 watts. The L2 cache is universally 2MB and the speed varies from 1.06GHZ to 2.33GHZ
Core Solo
Actually this is a core duo with one defective core (disabled)
Core 2 Duo
The most popular to be found. Made for both desktop and portables and is true 64 bit.
The "T" in the model number signifies portables and rated at 25-55 watts, a cache of 2 or 4MB and the higher the number the higher the clock speed.
The "E" in the number signifies desktops and is rated at between 55-75 watts, cache of 2 or 4 MB.
The higher the number the higher the clock speed.
Core 2 Extreme
Higher clock speed with a cache of 4 MB. There is a quad core version of this with a cache of 8 MB but as I understand it games producers are saying that it is currently not financially possible to produce games for a quad core. Many enhancements for video editing etc.
Turion 64 X2
Made for portables (64 bit)
Athlon 64 X2
Made for desktops. The higher the model number the higher the clock speed. Cache sizes are smaller than Intel´s but this has no effect on processing speed (It doesn´t need as much due to shorter pipelining).
Athlon 64 FX
Available in both dual and quad core types. It is an enhanced version of the 64 X2 with higher clock speeds and enhancements for gamers and heavy duty users such as video editors (see Core 2 extreme)