udev: persistent scsi disk names

cothgr · 06-27-2014, 07:48 AM

I have one IDE Controller and one SATA Controller. SATA has two slots.
How can I bind disk names in /dev to disk location by using udev, i.e
- IDE disk should be named /dev/sda;
- SATA 1 disk should be named /dev/sdb;
- SATA 2 disk should be named /dev/sdc?

There are addresses of disks:
- IDE : pci-0000:00:1f.1-scsi-0:0:0:0;
- SATA 1: pci-0000:00:1f.2-scsi-0:0:0:0;
- SATA 2: pci-0000:00:1f.2-scsi-0:0:1:0.

smallpond · 06-27-2014, 02:51 PM

The persistent names for disks are not the sda, sdb, etc. Init for different disk controllers runs in parallel, so those names are not guaranteed to be the same after reboot. Udev creates persistent names of the form:

Quote:

/dev/disk/by-uuid/39b99e5f-a117-44ee-a093-036b410b813d

which will always link to the same physical drive. To boot from this you would put this line in /etc/fstab

Quote:

UUID=39b99e5f-a117-44ee-a093-036b410b813d /boot ext4 defaults 1 2

cothgr · 06-27-2014, 03:28 PM

I can't use UUID, because different disks can be inserted in the slot. I wanna guarantee that any disk inserted in the first slot of SATA controller named sdb, in the second slot - sdc.

jefro · 06-27-2014, 04:44 PM

"Persistent naming methods

There are four different schemes for persistent naming: by-label, by-uuid, by-id and by-path. For those using disks with GUID Partition Table (GPT), two additional schemes can be used by-partlabel and by-partuuid. You can also use static device names by using Udev. "

https://wiki.archlinux.org/index.php...naming_methods

If you could control bios order then that could be a way.

Newer linux is moving to the BSD model where everything has a location. Not sure that is on disk's yet but maybe.