Inconsistent dnames on deployed machines

[Ante Karamatić]

When deploying bcache devices, there is no way to consistently name devices across the machines.

I have three machines, all with identical hardware and with identical configuration (curtin data attached). Device name for / for all machines in MAAS is bcache0. This is also expressed in curtin data.

However, upon deployment, on two machines I get:

/dev/disk/by-dname/bcache1 -> /dev/bcache4 (mounted as /)

On third I get:

/dev/disk/by-dname/bcache2 -> /dev/bcache3 (mounted as /)

While nobody expect consistent /dev/bcache naming, /dev/disks/by-dname/bcache naming must be consistent. Because udev rules for bcache* devices must contain UUIDs. Ie, udev rule (for server1):

SUBSYSTEM=="block", ACTION=="add|change", ENV{DEVNAME}=="/dev/bcache0", SYMLINK+="disk/by-dname/bcache0"

should in fact be:

SUBSYSTEM=="block", ACTION=="add|change", ENV{ID_FS_UUID_ENC}=="4d646141-dbc4-43f7-9f06-5d521dc74515", SYMLINK+="disk/by-dname/bcache0"

While this solves the problem with filesystems and would uniformly solve /dev/disks/by-dname/bcache links, it doesn't solve partitioning problem.

[Ryan Harper (raharper)]

Can you include the install.log from a system? Which curtin version is being used? The udev rules you show are from curtin 18.1-1 or less. In Bionic and Cosmic (18.1-5) where bcache dnames have been fixed to use uuid of the backing disk look like:

SUBSYSTEM=="block", ACTION=="add|change", ENV{CACHED_UUID}=="272a62c4-ed8f-4714-8909-78720ffad1e5", SYMLINK+="disk/by-dname/cached_array"

[Ante Karamatić (ivoks)]

It says:

May 15 14:31:03 server3 cloud-init[1132]: curtin: Installation started. (18.1-5-g572ae5d6-0ubuntu1)

[Ryan Harper (raharper)]

Well, shoot. It didn't make bionic;

commit aa003740b4d70a2ddb7f9f5ad51de7a10034d012 (HEAD -> ubuntu/devel,
tag: ubuntu/18.1-5-g572ae5d6-0ubuntu1,
raharper/ubuntu/devel/newupload-20180418)
Author: Ryan Harper <email address hidden>
Date: Wed Apr 18 10:15:57 2018 -0500

    releasing curtin version 18.1-5-g572ae5d6-0ubuntu1

commit 12d7163cea870b7e76f36249ffc5eab7a29c5582
Author: Ryan Harper <email address hidden>
Date: Thu Apr 19 10:47:20 2018 -0500

    make_dname for bcache should use backing device uuid

On Tue, May 15, 2018 at 10:36 AM, Ante Karamatić
<email address hidden> wrote:
> It says:
>
> May 15 14:31:03 server3 cloud-init[1132]: curtin: Installation started.
> (18.1-5-g572ae5d6-0ubuntu1)
>
>
> ** Attachment added: "messages"
> https://bugs.launchpad.net/curtin/+bug/1771342/+attachment/5139872/+files/messages
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1771342
>
> Title:
> Inconsistent dnames on deployed machines
>
> To manage notifications about this bug go to:
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[Ryan Harper (raharper)]

Is it possible to give curtin daily a test to confirm? We're working on a new upload to cosmic and an SRU to bionic, artful and xenial.

https://launchpad.net/~curtin-dev/+archive/ubuntu/daily

[Ante Karamatić (ivoks)]

Yes, daily works as expected!