udev rule to make certain ports always correspond to certain devices

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QUESTION :

Basically my problem is that I am on a server which constantly switches around hdd’s. What I want to achieve is have having devices tied to the physical ports on the hardware.

like /dev/sda is port 0 /dev/sdb is port 0 and so on.

I have been reading about udev rules and it always comes back to using serials and such. however since my hardware is constantly changing I can’t use that. I need to assign ports to device files.

Is such a thing possible?

ANSWER :

I’ve done this for external hard drives. I got my info using lsscsi, which will print something like the following:

[0:0:0:0]    disk    <descriptor>    /dev/sda
[1:0:0:0]    disk    <descriptor>    /dev/sdb
[2:0:0:0]    cd/dvd  <descriptor>    /dev/sr0

Where 0,1,2 correspond to the port IDs. Then something similar to the following rule should do what you want:

SUBSYSTEM=="block", KERNEL=="sd*1", KERNELS=="1:0:0:0", SYMLINK+="<label_1>"

(Note I haven’t checked that this works for internal drives – my external ones needed ‘usb’ rather than ‘block’ as the subsystem type)

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