Linux match drive labels to drive slots

ls -l /sys/block/sd{a,b,c,d}
lrwxrwxrwx 1 root root 0 Apr  9 01:24 /sys/block/sda -> ../devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda
lrwxrwxrwx 1 root root 0 Apr  9 01:24 /sys/block/sdb -> ../devices/pci0000:00/0000:00:1f.2/host1/target1:0:0/1:0:0:0/block/sdb
lrwxrwxrwx 1 root root 0 Apr  9 01:24 /sys/block/sdc -> ../devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sdc
lrwxrwxrwx 1 root root 0 Apr  9 01:24 /sys/block/sdd -> ../devices/pci0000:00/0000:00:1f.2/host5/target5:0:0/5:0:0:0/block/sdd

On PCI bus 1, PCI device 00:1f.2 is my SATA controller, a Intel Corporation 82801HB (ICH8) 4 port SATA AHCI Controller (rev 02). It provides 4 hosts to each of which I have attached a disk.

To get that ID, Instead of looking into the target structure, we're looking into the scsi_host structure. It has a directory for the host and in it a file unique_id. That's the ID appended to ata.

So for each of the hosts above I can display the ID like this:

dirk@topo ~ $ for host in 0 1 4 5; do echo -n host${host}:; cat /sys/devices/pci0000:00/0000:00:1f.2/host${host}/scsi_host/host${host}/unique_id; done
host0:1
host1:2
host4:5
host5:6