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Disk Device Names


On Mac OS X, the disk device name entries in the “/dev” directory are dynamic. Each time a device is connected to the computer it is assigned a disk name based solely on what slot is available. This means that these names cannot be used to identify a disk in a persistent manner. In Solaris, on the other hand, the disk names are persistent and are used in the zfs label to identify the expected path to a zfs virtual device (vdev).

Our solution to this fundamental difference is to provide alternate device names in a /dev/dsk/ directory that are persistent. These names are based on the GPT UUID of the device and will always uniquely identify a zfs virtual device regardless of how it is attached to the system. These persistent alternate names are created on demand whenever a ZFS labeled device is discovered by the system.

You can use the ls -l command to see the persistent names (and the temporary disk name that they refer to):

$ ls -l /dev/dsk/
lrwxr-xr-x  1 root  wheel  12 Oct 17 01:04 GPTE_6A6490B2-DE02-42E7-8678-9AA647FB291F -> /dev/disk0s2
lrwxr-xr-x  1 root  wheel  12 Oct 17 01:08 GPTE_B0A6CC2D-315C-4EF3-AB4A-3EAA4CDA1E14 -> /dev/disk3s2

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