The inconsistency in device naming is documented in
https://docs.openstack.org/nova/pike/user/block-device-mapping.html#intermezzo-problem-with-device-names
.
Similar to Tim's suggested approach, you can also mount the device by its
UUID. A while back I wrote a small, relatively untested, Python script to
which modifies fstab & replaces the device names with UUID=<device UUID>
(see attached). It depends on Augeas (python-augeas) to modify fstab.
This script can be downloaded into the Instance using cloud-init, and then
executed on initial boot with runcmd.
—
Blake Covarrubias
Product Manager
Platform9 Systems, Inc
On Thu, Jan 25, 2018 at 11:13 PM, Tim Bell <tim.b...@cern.ch> wrote:
> Labels can be one approach where you mount by disk label rather than device
>
>
>
> Creating the volume with the label
>
>
>
> # mkfs -t ext4 -L testvol /dev/vdb
>
>
>
> /etc/fstab then contains
>
>
>
> LABEL=testvol /mnt ext4 noatime,nodiratime,user_xattr 0 0
>
>
>
> You still need to be careful to not attach data disks at install time
> though but it addresses booting order problems.
>
>
>
> Tim
>
>
>
> *From: *Jean-Philippe Méthot <jp.met...@planethoster.info>
> *Date: *Friday, 26 January 2018 at 07:28
> *To: *"Logan V." <lo...@protiumit.com>
> *Cc: *openstack-operators <openstack-operators@lists.openstack.org>
> *Subject: *Re: [Openstack-operators] Inverted drive letters on block
> devices that use virtio-scsi
>
>
>
> Yea, the configdrive is a non-issue for us since we don’t use those. The
> multi-drive issue is the only one really affecting us. While removing the
> second drive and reattaching it after boot is probably a good solution, I
> think it’s likely the issue will come back after a hard reboot or
> migration. Probably better to wait before I start converting my multi-disk
> instances to virtio-scsi. If I am not mistaken, this should also be an
> issue in Pike and master, right?
>
>
>
> Jean-Philippe Méthot
>
> Openstack system administrator
>
> Administrateur système Openstack
>
> PlanetHoster inc.
>
>
>
>
>
>
>
>
>
> Le 26 janv. 2018 à 14:23, Logan V. <lo...@protiumit.com> a écrit :
>
>
>
> There is a small patch in the bug which resolves the config drive
> ordering. Without that patch I don't know of any workaround. The
> config drive will always end up first in the boot order and the
> instance will always fail to boot in that situation.
>
> For the multi-volume instances where the boot volume is out of order,
> I don't know of any patch for that. One workaround is to detach any
> secondary data volumes from the instance, and then reattach them after
> booting from the one and only attached boot volume.
>
> Logan
>
> On Thu, Jan 25, 2018 at 10:21 PM, Jean-Philippe Méthot
> <jp.met...@planethoster.info> wrote:
>
> Thank you, it indeed seems to be the same issue. I will be following this
> bug report. A shame too, because we were waiting for the patch to allow us
> to setup 2 drives on virtio-scsi before starting to make the change. In the
> meantime, have you found a way to circumvent the issue? Could it be as easy
> as changing the drive order in the database?
>
>
> Jean-Philippe Méthot
> Openstack system administrator
> Administrateur système Openstack
> PlanetHoster inc.
>
>
>
>
> Le 26 janv. 2018 à 13:06, Logan V. <lo...@protiumit.com> a écrit :
>
> https://bugs.launchpad.net/nova/+bug/1729584
>
>
>
> _______________________________________________
> OpenStack-operators mailing list
> OpenStack-operators@lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
>
>
#!/usr/bin/env python
"""Updates /etc/fstab to reference mounted devices by UUID.
Default mount points use device name. This script changes them to use UUID
which resolves issues in virtual environments where libvirt does not reliably
(re-)attach devices with a consistent name.
"""
import augeas
import subprocess
def _get_dev_uuid(dev):
cmd = ['blkid', '-c', '/dev/null', dev]
try:
result = subprocess.check_output(cmd).split()
for col in result:
if col.startswith('UUID='):
return col.replace('"', '')
return None
except Exception as excp:
pass
def main():
"""Main entry point."""
aug = augeas.Augeas(root='/')
changed = False
fstab_path = '/files/etc/fstab'
# Iterate over fstab entries
entries = aug.match(fstab_path + '*')
for entry in entries:
id_num = entry.split('/')[-1]
# Obtain the mount options for a particular entry
dev_options = aug.get("{0}/{1}/{2}".format(fstab_path, id_num, 'opt'))
vfs_type = aug.get("{0}/{1}/{2}".format(fstab_path, id_num, 'vfstype'))
# Skip entries with no device options
if not dev_options:
continue
if 'defaults' in dev_options or 'auto' in dev_options \
and vfs_type != 'swap':
spec_path = "{0}/{1}/{2}".format(fstab_path, id_num, 'spec')
spec = aug.get(spec_path)
# If the device begins with a slash
if spec.startswith('/'):
dev_uuid = _get_dev_uuid(spec)
if dev_uuid:
# Update device to use UUID instead of device name
aug.set(path=spec_path, value="{0}".format(dev_uuid))
changed = True
if changed:
aug.save()
if __name__ == '__main__':
main()
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