** Description changed: === Begin SRU Template === - [Impact] + [Impact] There is a race condition that occurs when cloud-init tries to partition a block device (/dev/sdb) and then put a filesystem on a partition on it. It is possible that cloud-init tries to run mkfs on /dev/sdb1 after partitioning the device /dev/sdb but before the partition device node '/dev/sdb1' exists. When this race condition occurs, cloud-init will fail to make the "ephemeral" device available to the user on Azure. [Test Case] A reliable reproduce test case is hard to come by here. The failure case is believed to be well understood. - [Regression Potential] + [Regression Potential] There should be very little chance for regression, as essentially all the change does is change: 1. sgdisk -n 1:0:0 /dev/sdb 2. mkfs.ext4 /dev/sdb1 to 1. sgdisk -n 1:0:0 /dev/sdb 1a udevadm settle 1b blockdev --rereadpt - 1c usdevadm settle + 1c udevadm settle 2. mkfs.ext4 /dev/sdb1 The steps '1b' and '1c' above are not necessary, but were present already in the method. They serve here as additional wait. [Other Info] The change that fixes this is viewable at [1]. For context, viewin all of cc_disk_setup.py [2]. Basically we just add a call to read_parttbl [3] to exec_mkpart_gpt after invoking a sgdisk command that partitions a disk. read_partbl basically does a udevadm settle which fixes the race condition that was seen. [1] https://git.launchpad.net/cloud-init/commit/?id=29348af1c889931e8973f8fc8cb090c063316f7a [2] https://git.launchpad.net/cloud-init/tree/cloudinit/config/cc_disk_setup.py?id=29348af1c889931e8973f8fc8cb090c063316f7a [3] https://git.launchpad.net/cloud-init/tree/cloudinit/config/cc_disk_setup.py?id=29348af1c889931e8973f8fc8cb090c063316f7a#n674 - === End SRU Template === - - The symptom is similar to bug 1611074 but the cause is different. In this case it seems there is an error accessing /dev/sdb1 when lsblk is run, possibly because sgdisk isn't done creating the partition. The specific error message is "/dev/sdb1: not a block device." A simple wait and retry here may resolve the issue. + The symptom is similar to bug 1611074 but the cause is different. In + this case it seems there is an error accessing /dev/sdb1 when lsblk is + run, possibly because sgdisk isn't done creating the partition. The + specific error message is "/dev/sdb1: not a block device." A simple wait + and retry here may resolve the issue. util.py[DEBUG]: Running command ['/sbin/sgdisk', '-p', '/dev/sdb'] with allowed return codes [0] (shell=False, capture=True) cc_disk_setup.py[DEBUG]: Device partitioning layout matches util.py[DEBUG]: Creating partition on /dev/disk/cloud/azure_resource took 0.056 seconds cc_disk_setup.py[DEBUG]: setting up filesystems: [{'filesystem': 'ext4', 'device': 'ephemeral0.1', 'replace_fs': 'ntfs'}] cc_disk_setup.py[DEBUG]: ephemeral0.1 is mapped to disk=/dev/disk/cloud/azure_resource part=1 cc_disk_setup.py[DEBUG]: Creating new filesystem. cc_disk_setup.py[DEBUG]: Checking /dev/sdb against default devices cc_disk_setup.py[DEBUG]: Manual request of partition 1 for /dev/sdb1 cc_disk_setup.py[DEBUG]: Checking device /dev/sdb1 util.py[DEBUG]: Running command ['/sbin/blkid', '-c', '/dev/null', '/dev/sdb1'] with allowed return codes [0, 2] (shell=False, capture=True) cc_disk_setup.py[DEBUG]: Device /dev/sdb1 has None None cc_disk_setup.py[DEBUG]: Device /dev/sdb1 is cleared for formating cc_disk_setup.py[DEBUG]: File system None will be created on /dev/sdb1 util.py[DEBUG]: Running command ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/sdb1', '--nodeps'] with allowed return codes [0] (shell=False, capture=True) util.py[DEBUG]: Creating fs for /dev/disk/cloud/azure_resource took 0.008 seconds util.py[WARNING]: Failed during filesystem operation#012Failed during disk check for /dev/sdb1#012Unexpected error while running command.#012Command: ['/bin/lsblk', '--pairs', '--output', 'NAME,TYPE,FSTYPE,LABEL', '/dev/sdb1', '--nodeps']#012Exit code: 32#012Reason: -#012Stdout: ''#012Stderr: 'lsblk: /dev/sdb1: not a block device\n'
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1626243 Title: Cloud-init fails to write ext4 filesystem to Azure Ephemeral Drive To manage notifications about this bug go to: https://bugs.launchpad.net/cloud-init/+bug/1626243/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
