Linux ATA errors: Translating to a device name?

Question

When a Linux box gets an ATA error, it syslogs it with a message identifying the disk as "ata%d.00". How do I translate that to a device name (e.g. /dev/sdb)? I feel like this should be trivial, but I cannot figure it out.

Answer 1

Look at /proc/scsi/scsi, which will look something like this:

$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3250823AS      Rev: 3.03
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3750528AS      Rev: CC44
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3750330AS      Rev: SD1A
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi10 Channel: 00 Id: 00 Lun: 00
  Vendor: WDC WD20 Model: EARS-00MVWB0     Rev:     
  Type:   Direct-Access                    ANSI SCSI revision: 02

scsi0 id 0 is sda and ata1.00, scsi1 id 0 is sdb and ata2.00, etc.

Also look at /var/log/dmesg, which shows the ata driver loading info and will make things a little clearer. Look for the line starting "libata".

Answer 2

The easiest way is to review the kernel log from boot, since the drive device names are mixed in from various sources (eg USB drives), or are assigned based on type of device (ie cdrom may be scdX instead, and everything has a sgX). In practice, unless you have mixed different kinds of buses (eg SATA+USB) the lowest numbered ata device is going to be sda unless it's a cdrom device.

Depending on your system, it might be divined by wandering around sysfs. On my system ls -l /sys/dev/block reveals that 8:0 (major:minor from /dev entry) points to /sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda Likewise, ls -l /sys/class/ata_port reveals that ata1 points to /sys/devices/pci0000:00/0000:00:1f.2/ata1/ata_port/ata1 which is on the same PCI sub-device.

Since I use SATA, and only one drive is on each port I can deduce that ata1.00 = sda. All of my drives are .00, I suspect that if I used a port multiplier, my drives would be given .01, .02, .03 etc. Looking at other people's logs PATA controllers use .00 and .01 for master and slave, and based on their logs if you have ataX.01, the .01 should be mapped to the "ID" in the host:channel:ID:LUN folder from the /sys/dev/block/ listing. If you have multiple ataX/ and hostY/ folders in the same PCI device folder, then I suspect that the lowest numbered ataX folder matches the lowest numbered hostY folder.