drive assignments

Jason unleet at
Wed Nov 21 17:47:42 EST 2001

> /hdc is primary drive on the second IDE controler, /hdd would be the slave
> drive on the second controler. See the pattern? The same pattern would
> hold for SCSI drives however, I'm not sure if you would be limitted to two
> drives per SCSI controler. I don't have any SCSI hard drives here so not
> very familiar with SCSI protocols.
SCSI basically works the same way. The only difference is that the drives are 
"lettered" in the order they are detected, starting with controller 1, ID 0, 
LUN 0. So /dev/sda is the device with the lowest ID number on the first 
controller, regardless of the actual ID number. There is one caveat, the 
actual SCSI controller, while it has an ID number is not given a device node 
(though this may bi different if your kernel includes the "devfs" package.

Also, as a feature, there are /dev/scd? devices, for CDROM, CD-R(W) and DVD 
drives on your SCSI busses, these are numbered in the order detected starting 
with 0, otherwise the same way hard drives are. These are in addition to, not 
in place of, the /dev/sd? entries. There are also "SCSI Generics" available, 
these are listed as /dev/sg?, and again, numbered in the order detected, 
atarting with 0 (seeing a pattern here?). SCSI generics include things such 
as SCSI-based scanners, CD-R and CD-RW drives and things such as that (yes, 
this can mean that a single CD drive will be listed three times if it's 
recordable, or twice if not).

If anyone actually needed that information, I hope it helped, if not, I hope 
it was at least interesting ;-)

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