The /dev/disk/ directory contains symlinks to different symbolic names that point back to any attached raw device. These symbolic names are useful in determining what names for each device are persistent regardless of which ports or protocols are used.
The symlinks used by these persistent names are divided by type in the following /dev/disk/ subdirectories:
by-id/
Names devices by SCSI VPD page 0x80 or 0x83 data
by-uuid/
Names devices based on file system Universally Unique Identifier (UUID)
by-label/
Names devices based on file system label
by-path/
Names devices by sysfs path. For fibre channel this may name the device using the PCI info and Host:BusTarget:LUN info.
For iSCSI devices, by-path/ names use the target name and portal information. Note that by-path names are not reliable if you have two multiple paths to the same portal.
In addition to this, you can also use udev rules to implement persistent naming. For more information about this, refer to man udev.