Tech Features

RAID system: Hard drive chains pep up slow data

By Till Wortmann Jul 10, 2005, 6:15 GMT

Munich - You can never have enough storage space. Particularly when video files are added to the equation, capacity requirements grow fast. RAID, or Redundant Array of Independent Disks, can help.

The term refers to the bundling of hard drivers into one virtual storage system. It can be used to increase a PCs power or to protect against data loss.

"RAID systems are getting more important every day," says Christian Anderka, of chipmaker Intel.

RAID has traditionally been used only for corporate computing. The recent introduction of RAID-ready PCs for home usage, though, has increased the technology's profile among consumers. Falling prices for hard drives have only sped up the trend.

"The technology has gotten very cheap," says Christof Windeck, editor at the computer magazine "c't."

Yet PC users should not underestimate the difficulty of installing RAID. It can be difficult even for those with motherboards that have built-in RAID controllers, and it can put your data at risk.

"Make one mistake and the entire hard drive contents may be gone," warns Christian Goegelein, deputy editor at PC Games Hardware magazine. In order to avoid problems, it is best to use hard drives from the same manufacturer wherever possible.

Experts distinguish various RAID variants, also known as levels. If speed is paramount, then RAID 0 is the choice - the controller then spreads data over various hard drives. This process, also called striping, increases the read speed. This is important for games that need to switch playing scenarios in the blink of an eye.

"A RAID 0 system shortens loading time for games by up to 30 per cent," Goegelein explains.

This doesn't make the game itself any quicker, just the loading of data from the hard disk. But for Goegelein, the merits are mixed at best. "In most cases, RAID 0 isn't worth it for gamers, since they'll hardly notice the effect while playing anyway."

Striping also has the disadvantage that it increases the risk of total data loss. If even one of the hard drives becomes corrupted, all data can become unusable.

Gamers are better advised to install one single, fast hard drive into their PC instead of RAID, Goegelein claims. That is cheaper and brings equally good performance, he feels.

Those looking to store important data like tax records or wedding footage on a PC should be thinking about data security. RAID 1 is designed to help with this problem.

The PC records everything sent to the hard drive on two or more drives at once. Experts refer to this process as "mirroring".

"RAID 1 protects against data loss from defective hard drives, but not from accidental deletion," notes Guido Lohmann from Bavaria's "PC Magazin".

The advantages of both processes are combined in RAID 5, which requires three hard drives. "It is quick, secure, and involves little loss of capacity," Lohmann says. The expert feels that RAID 5 can serve as a good back-up solution.

RAID 10 pulls yet another hard drive into the circuit. It's important to remember, however, that extra hard drives consume extra power - up to 20 watts per unit in extreme cases.

One simple but practical solution for home users is the Matrix RAID. The process, designed by Intel, combines the advantages of RAID 0 and 1, with high performance and quick data protection, but uses only two hard drives.

This keeps costs down. Matrix RAID splits the individual hard drives into partitions, one for mirroring, one for striping. The process only works with Intel chip sets from the 8xx and 9xx series and their corresponding controllers.

Hard drives are highly sensitive, so users should handle the hard drives in the RAID system with care. Proper cooling is important.

"A computer that runs just fine with one hard drive may overheat and crash if a second one is built in," Goegelein warns. Extra cooling fans are the only real protection against this - but bring with them increased noise.