[shuey@fmepnet.org: Re: Bug#351606: multipath mis-detects SATA raid1 by default]

[Bastian Blank <waldi@debian.org>]

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Hi folks

I got the following bugreport against multipath-tools, which by default
uses scsi_id to detect multiple paths.

scsi_id on SATA devices (via libata) returns a string like:
| 0ATA_ST3160827AS_Linux_ATA-SCSI_simulator

Is is the a bug in the kernel to return a static string for inquiry page
0x83 queries or a bug in scsi_id to use this page by default?

Page 0x80 queries seems to always return the serial number of the disks;
0x83 queries returns a static string with libata and the wwnn (or such)
on my fiber channel disks.

Bastian

----- Forwarded message from Michael Shuey <shuey@fmepnet.org> -----

From: Michael Shuey <shuey@fmepnet.org>
To: Bastian Blank <waldi@debian.org>
Subject: Re: Bug#351606: multipath mis-detects SATA raid1 by default
Date: Thu, 9 Feb 2006 08:26:14 -0500
Cc: 351606@bugs.debian.org

On Tuesday 07 February 2006 11:19, Bastian Blank wrote:
> On Sun, Feb 05, 2006 at 09:35:29PM -0500, Michael Shuey wrote:
> > On bootup, multipath correctly handles my FC-based SAN.  However, it
> > also detects the two SATA drives in the system.  Since the two drives
> > are in a raid1, are physically identical, and represented by SCSI block
> > devices (/dev/sd*), multipath always assumes these are a single drive
> > with two valid paths, and creates a new multipath group.
>
> Which name does multipath use for them?
> Do they have the same serial number?

The SATA disks get put in a multipath named 
"0ATA_ST3160827AS_Linux_ATA-SCSI_simulator".  I'm not entirely sure how to 
check their serial numbers, since their path name isn't their serial number 
(as appears to be the case with my FC disks).

Let me know if there's something you'd like me to dig out of sysfs.

----- End forwarded message -----

-- 
The man on tops walks a lonely street; the "chain" of command is often a noose.

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