Discussion:
udev "database"
Leroy Tennison
2018-09-13 22:11:26 UTC
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We created /etc/udev/rules.d/70-persistent-net.rules under Ubuntu 14 and later upgraded to Ubuntu 16. We have rebooted numerous times and the name-to-MAC-address mapping continued to be applied. However, one of the units we were using this on failed and we did a chassis replacement (kept the original hard drive). Even after editing the MAC address values in the rules file, the mappings were no longer applied at boot. I learned that the format changed between Ubuntu 14 and 16 and that the old format no longer worked (had to remove the KERNEL== ..." parameter from each line).

What bothers me is why the old file format still works on existing Ubuntu 16 systems and what kinds of other things might break that. Somehow there must be a "database" (I use the term in the loosest sense possible) or scheme which says in effect "if nothing has changed use the previous values". How does this work and does it work differently under netplan?

Thanks for your help.


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Robie Basak
2018-09-14 09:50:06 UTC
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Hi,

On Thu, Sep 13, 2018 at 10:11:26PM +0000, Leroy Tennison wrote:
> What bothers me is why the old file format still works on existing
> Ubuntu 16 systems and what kinds of other things might break that.
> Somehow there must be a "database" (I use the term in the loosest
> sense possible) or scheme which says in effect "if nothing has changed
> use the previous values". How does this work and does it work
> differently under netplan?

Please see
https://lists.ubuntu.com/archives/ubuntu-devel/2015-May/038761.html and
in particular the paragraph starting "For upgrades".

Nothing is different "under netplan" - network interfaing renaming is
out of its scope and works exactly the same way for ifupdown as it does
for netplan.

Hope this helps,

Robie
Leroy Tennison
2018-09-14 16:48:27 UTC
Permalink
Wow, what an education. Thank you for your very helpful response. The answers I have gotten from the Ubuntu server team have always been very beneficial and I appreciate it.


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Leroy Tennison
Network Information/Cyber Security Specialist
E: ***@datavoiceint.com
2220 Bush Dr
McKinney, Texas
75070
www.datavoiceint.com
TThis message has been sent on behalf
of a company that is part of the Harris Operating Group of
Constellation Software Inc. These companies are listed
here
.
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Operating Group
please notify us
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________________________________________
From: Robie Basak <***@ubuntu.com>
Sent: Friday, September 14, 2018 4:50 AM
To: Leroy Tennison
Cc: ubuntu-***@lists.ubuntu.com
Subject: [EXTERNAL] Re: udev "database"

Hi,

On Thu, Sep 13, 2018 at 10:11:26PM +0000, Leroy Tennison wrote:
> What bothers me is why the old file format still works on existing
> Ubuntu 16 systems and what kinds of other things might break that.
> Somehow there must be a "database" (I use the term in the loosest
> sense possible) or scheme which says in effect "if nothing has changed
> use the previous values". How does this work and does it work
> differently under netplan?

Please see
https://lists.ubuntu.com/archives/ubuntu-devel/2015-May/038761.html and
in particular the paragraph starting "For upgrades".

Nothing is different "under netplan" - network interfaing renaming is
out of its scope and works exactly the same way for ifupdown as it does
for netplan.

Hope this helps,

Robie
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