A new device naming scheme

Posted Apr 12, 2004 20:48 UTC (Mon) by Peter (guest, #1127) [Link]

This issue can't be a Linux only issue. What are other OSs doing?

AIX has a dynamic /dev created by userspace during boot. Similar to udev, conceptually. Hard disks get named hdisk0, hdisk1, etc. in the order they are detected; after initially being detected by the system, their UUID or something is stored in a registry (the ODM) so that they always get the same identifier thereafter. (This persistence of names is not even all that important for disks, since AIX almost always uses disks via its LVM, which has no need to care about device IDs since it uses its own superblocks.)

So, AIX remembers all the devices it has ever detected on your system - or been told about via /sbin/mkdev. Devices it has successfully initialised are put in the available state, which involves creating the device node in /dev; devices which were not detected are put in the defined state, where device nodes in /dev are not automatically created. Major numbers are assigned dynamically, I think even for core stuff like /dev/null. And if you want to purge old entries from its database for stuff you no longer have plugged in, you have to do this manually, with /sbin/rmdev -d.