[wplug] iscsi-lvm1 device inconsistancy

[Brandon Poyner]

On 1/28/07, G.Pitman <gpitman at gmail.com> wrote:
> Hello,
> I have found out the hard way that linux iscsi device mapping is pretty consistant until it's not, and then you've got a problem.
>
> I have 9 LVM physical volumes mounted to devices /dev/sd[c-k] and we are running a high availability cluster under RHEL3. Upon reboot of one of the front ends, it decided that it would switch the last two PVs so that the data that LVM expects to find on sdj is now on sdk and mounting directories is full of suprises. I have seen that in LVM2 you can specify volume labels or UUIDs to solve this issue but I am unfortunately running LVM1.
> any input or brainstorming is invited.

Well, I guess one option is to upgrade to RHEL4, which if you have a
current RHN contract you could be entitled to it.  You can also use
CentOS4 if you don't need support.  Then again upgrading can be a lot
of work.

It might make a difference on what you're using for your iSCSI
initiator.  A RHEL4 document on the initiator included with the OS
specifically addresses the problem you're seeing by recommending one
of two things:

  a) Udev - udev can be used to provide persistent names for all types of
  devices. scsi_id program which provides serial number for a given block
  device is integrated with udev and can be made use for persistency.

  b) UUID & LABEL based mouting - Filesystems and LVM provide facility
  to mount devices by UUID or LABEL and hence ensure persistency
  across reboots.

http://people.redhat.com/mchristi/iscsi/RHEL4/doc/readme

Can you use something such as 'devlabel' as I don't believe RHEL3 uses udev?

-- 
Brandon