topic Re: Undestanding device files for SCSI hdds conneted in SCSI controller in Operating System - Linux

Undestanding device files for SCSI hdds conneted in SCSI controller

senthil_kumar_1 — Wed, 18 Mar 2009 06:33:43 GMT

Hi

I want to clarify myself on this.

my scenario:

1) There is one scsi card in my HP proliant server.
2) The LINUX server is installed in this.
3) I have connected one SCSI cable in that scsi card's scsi controller and I have connectedd 3 SCSI hdds in that that SCSI cable.

I have following questions

i) If RAID is not configured:

1) the device files for three scsi hdds will be c0d0, c0d1, c0d2 ... am i correct?

2) c0 is controller id. am i correct?

3) If there is two controllers (port) are available in one scsi card then the controller will be c0, c1. am i correct?

4) how many controller (port) will be availbe in one scsi card.

5) d0 is a disk id. I heard that we can connect 14 scsi hdds in one cable if scsi card supports. am i correct?

6) is there any jumper setting in scsi hdd to define the device id like d0, 1, d2 ..
OR it will be take automatically. how this happens. pls explain me.

ii) If RAID is configured:

1) The total three disks will be seen as one disk ex: "c0d0". am i correct?

Re: Undestanding device files for SCSI hdds conneted in SCSI controller

Peter_505 — Wed, 18 Mar 2009 11:28:49 GMT

1. Correct
2. Correct
3. Correct
4. Depends the HP U320 controller has two, the 6400 has two but with the EM there are a total of 4.
5. Not sure if it's 14 or 13...
6. If the drives are daisy chained then probably it's via SCSI ID, if plugged into a backplane then automagically assigned.

Terminology:

cxdxpx

cx= controller
dx= physical disk drive
px= partition on the disk

df -h
Filesystem Size Used Avail Use% Mounted on
/dev/cciss/c1d0p1 594G 3.0G 561G 1% /
/dev/cciss/c0d0p1 487M 17M 445M 4% /boot
/dev/cciss/c0d1p1 270G 188M 269G 1% /abc
/dev/cciss/c0d1p2 1.0T 500G 498G 1% /def

Re: Undestanding device files for SCSI hdds conneted in SCSI controller

Heironimus — Wed, 18 Mar 2009 15:39:06 GMT

You'll only have the cciss devices if the SCSI controller you're talking about is a SmartArray controller. If it's a regular SCSI card or some other type of RAID controller you'll usually get /dev/sdX devices for the drives instead.