Comment 23 for bug 1735839

On Wed, Jan 30, 2019 at 6:20 PM Dmitrii Shcherbakov <
<email address hidden>> wrote:

> > Is this acceptable? Won't users file that as a bug?
>
> I suspect that either there is a very small amount of users or no users
> at all that depend on dname symlinks in VMs. Based on field engineering
> experience there are none because if VMs are created with a single block
> device (where root fs resides), file system paths are typically used in
> automation, not dname symlinks. None of our current bundles rely on by-
> dname symlinks with pod VMs.
>
> I don't like to use ad-hoc statistics to reason about behavioral changes
> but it is what it is considering the situation.
>

If you and MAAS are OK with this; I won't object. I'll just return any
bugs to you =)

>
> > That may be acceptable if we have a MAAS version released where dnames
> are stable (and enforced, though the question remains where to enforce
> this; in curtin or MAAS)?
>
> We cannot enforce that in every case, e.g. when I use virsh provider +
> my own domain XML without serial/wwid specified for block devices, I
> don't expect MAAS to parse domain XML and tell me there is something
> missing.
>
> However, I would warn a user via MAAS based on outputs of 00-maas-07
> -block-devices commissioning script: e.g. if '"SERIAL": "drive-
> scsi0-0-0-0"' is present, it is clearly not a persistent ID, and a user
> should be told that it cannot be relied on for persistent device
> symlinks.
>
> Likewise, if there is a physical device with a damaged EEPROM or
> otherwise inaccessible Vital Product Data (VPD), in which case
> serial/wwid wouldn't be accessible, MAAS should tell the user about
> that.
>
> To summarize: it's better to warn explicitly than fail commissioning.
>

Even better to have MAAS prevent users from including 'name' values for
disks
which don't have a serial attribute. I guess I'm also looking for MAAS to
do its part
for ensuring that dname is stable by refusing to allow users to create a
'name' on storage
devices if the don't have a persistent attribute.

>
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> report.
> https://bugs.launchpad.net/bugs/1735839
>
> Title:
> /dev/by-dname symlinks based on wwn/wwid
>
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