what is a "channel" on a raid controller?

[algorithm0]

I am working on a machine that has 2 raid controllers, with each controller having 2 channels. What on earth is the significance of a channel? How does a channel effect how my raid containers are set up?

any info you can throw at me would be most helpful.

[big poppa pump]

What kind of raid controllers are we talking about over here? IDE, SATA or SCSI?

[algorithm0]

What kind of raid controllers are we talking about over here? IDE, SATA or SCSI?

SCSI

[nmX.Memnoch]

A channel is a single connector for devices. SCSI controllers use IDs to determine a drives position (muhc like Master and Slave with IDE, but numbers instead). Each channel has an ID of 0 through 15, with the SCSI controller using one ID for itself (usually 7). SCSI controllers can have anywhere from 1 to 4 channels. With a 4 channel controller you can have up to 60 total devices connected. If you use hotswap drives then you'll likely have some sort of backplane they plug into. This will also take an ID (varies). The good thing about using hotswap with a backplane is that they usually auto assign the SCSI ID to the drive(s)...otherwise you have to manually set each drive, making sure that no two are set to the same ID.

See attached screenshot for an example of a system with multiple SCSI RAID controllers, one using the systems internal hotswap backplane, the other attached to two external drive enclosures.