Thursday, January 20, 2011

Debian and Multipath IO problem

Basically the situation is, I have a box running Debian, the box internally has an Intel SCSI RAID controller which is controlling 2 hard drives in RAID1 mode which is where the OS is installed.

Further, I have a QLogic fiber channel adapter that connects the unit to a Fiber Channel SAN.

My process of installation is I'll install Debian to the local drives, and leave the QLogic firmware out of it for the time being.

Then once I get the unit online, I'll install the firmware drivers.

This flops my internal drives from /dev/sda to /dev/sdc, which is a bit annoying, but recoverable. Probably should address these by UUID anyways.

Once I get back online, I have to install multipath-tools (the framework is a multipath framework).

However, once I reboot the machine again, it fails on boot after discovering multipath targets, saying my local drives are busy and cannot be mounted to /root.

Any help in what may be the problem here? Or at least how to disable multipath until after the unit boots and then ignores the internal drives?

  • How are the multi-path targets presented? What are the device names?

    tearman : They're presented as two devices (two LUNs). They're named /dev/sda and /dev/sdb
  • This appears to be a conflict with multipath-tools-boot and the SCSI controller. The workaround is to use software RAID for the time being.

    From tearman

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