[CentOS] How to map ata#.# numbers to /dev/sd numbers?

Thu Jan 28 20:23:00 UTC 2010
Peter Kjellstrom <cap at nsc.liu.se>

On Thursday 28 January 2010, Stephen Harris wrote:
...
> Now occasionally I see something like this in my logs
>
> ata7.01: exception Emask 0x0 SAct 0x0 SErr 0x0 a ction 0x0
...
> How do I tell what disk this is complaining about?  Is there a way
> to determine what ata7.01 maps to in terms of /dev/sd# values?
>
> /proc/scsi/scsi doesn't obviously match scsi# numbers to ata# numbers :-(

This seems quite hard to do. The following hack will match scsi hosts to 
libata-driver + number:

 $ for d in $(ls -d /sys/class/scsi_host/host?); do echo "$d $(cat \
   $d/proc_name) $(cat $d/unique_id)" ; done
/sys/class/scsi_host/host0 ahci 1
/sys/class/scsi_host/host1 ahci 2
/sys/class/scsi_host/host2 ahci 3
/sys/class/scsi_host/host3 ahci 4
/sys/class/scsi_host/host4 ahci 5
/sys/class/scsi_host/host5 ahci 6

This does not get you all the way though, but unless you have several 
different libata-drivers ahci 1-6 above will match ata1-ata6 (read "dmesg | 
less"...).

Once you know which scsi-host you're looking for the /dev/sdX name can be had 
from many sources (like the output of "lsscsi").

/Peter
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