qtparted shows strange devices

[Josh83]

hi all

i just bought a new notebook. i booted with knoppix to create partitions and stuff, and now qtparted shows me the following devices:

/dev/hda
/KNOPPIX/dev/ataraid/d0p1
/KNOPPIX/dev/ataraid/d0p2
/KNOPPIX/dev/ataraid/d0p5

/dev/hda seems clear to me, it's the normal harddisk. but what are the other 3 entries? what can i use them for?

thanks for info.
josh

[mr_ed]

Well now - lucky you! QTParted is telling you that you have a redundant array of hard drives right there in your laptop!

RAID is a technique for putting identical stuff on multiple drives. But instead of holding the duplicates off-line as spares, they're all online at the same time behind one processor (or one multiprocessor). It's used for two reasons: speed and reliability.

The time required to retrieve data from a drive is the bottleneck in the vast majority of processes now. With RAID, multiple requests that come in at the same time for access to the same data can all be handled quickly by one processor, and the data can be fetched from more than one drive simultaneously. Instant speed-up.

(If instead you need lots of computing power because you're modelling the earth's atmosphere - or a race car in a wind tunnel - you instead want a supercomputer or super-array of computers. Most of the world's fastest computers now run Linux on cheap motherboards. In the top five there's still one that isn't Linux (it's a proprietary machine designed and built specifically to be a supercomputer), but it's sinking fast in the ratings.)

The other use of RAID is for applications with absolutely zero tolerance for down time. As mechanical devices, drives will fail faster than other components that have no moving parts. So you have most of your backup drives already online. When one goes bad, you can swap it out with a spare while the server keeps running with the remaining drives.

ATA refers to non-ancient hard drives where the controller is packaged with the drive instead of on the motherboard or a plug-in board. It's an umbrella term for IDE, EIDE, Ultra-DMA and the like. SCSI drives, though, aren't ATA.

/KNOPPIX/dev/ataraid/d0p1

The right-hand end of this says "disk 0, partition 1." The other two are partitions 2 and 5. First off, there's widespread disagreement in the computer world as to whether to start counting with 0 or 1. Here, disk 0 is the first one.

The partition numbering, though, looks a little suspicious. Like it's referring to a normal hard drive with two primary partitions and one logical partition within an extended partition. Then there's the fact that they're showing up in /KNOPPIX, a directory on the Knoppix CD.

When you take the CD out and boot from hard drive, do those same entries show up?

Here's more info:

• - ATA - http://www.webopedia.com/TERM/A/ATA.html
  - RAID - http://www.webopedia.com/TERM/R/RAID.html
  - ATA RAID on Linux - http://www.murty.net/ataraid/

-- Ed

[Josh83]

wow thank you so far for your very helpful informations!

i remarked that those ataraid entries varied, sometimes there are more shown and sometimes less... i did not check this out yet... what should i do now?

[mr_ed]

I'd start by being suspicious. You just don't generally go to the store and by a RAID computer. And a laptop? And a configuration that jumps around?

Are you using any external drives - USB or firewire hard drives, maybe, or a USB pen drive or three? And how do you have your internal drive partitioned?

-- Ed

[Josh83]

@ mr_ed:
i gonna check that out. thank you!