[Bug 964957] Re: Installer warns "Could not stat device /dev/mapper/hostname-root - No such file or directory", works after retry

[dann frazier]

** Description changed:

- When I try to install Ubuntu Precise Pangolin with my filesystems on LVM
- volumes, it gives me this warning:
- 
-   Could not stat device /dev/mapper/hostname-root - No such file or
- directory.
- 
- If I select "Retry", everything works.
- 
- It appears that the LVs are created, but their entries in "/dev/mapper"
- don't exist yet when the rest of the system tries to use them.
- 
- After I retry, the entries do exist and so everything works.
- 
- An easy fix seems to be adding a short delay after creating the LVs, so
- they are ready by the time other parts of the install process begin.
- 
- I will attach a short video with some more information, along with the
- fix that worked for me.
+ [Impact]
+ Installs using LVM can fail due to a race with the message "Could not stat device /dev/mapper/$hostname-root - No such file or directory". This is very reproducible on some systems, but not others (presumably due to timing). I've had good luck reproducing w/ a kvm VM. During manual installs this is a fairly minor error - selecting "Retry" allows the install to continue. However, this is a fatal error on automated installs.
+ [Test Case]
+ Do an LVM install using d-i - manual or preseeded and look for the above error message.
+ [Regression Potential]
+ This introduced a new call into the udev stack, so a bug there could trip us up - but, it seems like if any such bug existed, we'd hit it already w/ one of the other settle calls.

** Patch added: "proposed debdiff for precise SRU"
   https://bugs.launchpad.net/ubuntu/+source/partman-auto-lvm/+bug/964957/+attachment/3365466/+files/add-settle.debdiff

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https://bugs.launchpad.net/bugs/964957

Title:
  Installer warns "Could not stat device /dev/mapper/hostname-root - No
  such file or directory", works after retry

Status in “partman-auto-lvm” package in Ubuntu:
  Fix Released

Bug description:
  [Impact]
  Installs using LVM can fail due to a race with the message "Could not stat device /dev/mapper/$hostname-root - No such file or directory". This is very reproducible on some systems, but not others (presumably due to timing). I've had good luck reproducing w/ a kvm VM. During manual installs this is a fairly minor error - selecting "Retry" allows the install to continue. However, this is a fatal error on automated installs.
  [Test Case]
  Do an LVM install using d-i - manual or preseeded and look for the above error message.
  [Regression Potential]
  This introduced a new call into the udev stack, so a bug there could trip us up - but, it seems like if any such bug existed, we'd hit it already w/ one of the other settle calls.

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