[asterisk-dev] Asterisk + DAHDI failure-resistance (non)

Matthew Jordan mjordan at digium.com
Mon Jul 8 08:05:16 CDT 2013

On Sat, Jul 6, 2013 at 7:07 AM, Oron Peled <oron.peled at xorcom.com> wrote:

> **
> Hi,
> Today's Asterisk+DAHDI state:
>    - If a single channel/span breaks...
>    - On the next asterisk restart -- no DAHDI channels at all!
>    - Is it acceptable in 2013?
> This could have been fixed for years.
> What happened on the DAHDI side?
>    - In 2008<http://lists.digium.com/pipermail/asterisk-dev/2008-July/033805.html>this problem was presented, with proposed solution.
>    - Few months later we had a prototype<http://svnview.digium.com/svn/dahdi?view=revision&revision=5443>of the DAHDI side.
>    - Tried to revive interest in 2010<https://gitorious.org/asterisk-tools/dahdi-linux/commit/6e5f2bb05fd309bacab570c80e6304b487d9c19b>
>    .
>    - In 2011 Shaun Raffle started a big revamp of DAHDI in different
>    direction. This resulted in the pinned-spans<http://lists.digium.com/pipermail/asterisk-dev/2011-October/051954.html>scheme which was part of DAHDI-
>    2.6.0.
>    - Since Nov-2011, it also included the required fixes for DAHDI-tools
>    (see the dahdi_cfg '-S<span>' and '-C<chan_list>' options).
>    - Which means DAHDI is "ready" -- each channel/span may be handled
>    independently of the others.
> What happened in Asterisk?
>    - Dynamic channel removal (DAHDI_EVENT_REMOVED)was added some eons ago
>    (in the Zaptel days).
>    - It had a bug with D-Channels. Tzafrir uploaded a fix to review-board
>    (726) <https://reviewboard.asterisk.org/r/726/> some 3 years ago -- it
>    still lingers there instead of being applied to all supported asterisk
>    versions.
>    - Dynamic channel addition code was uploaded to review-board (1598)<https://reviewboard.asterisk.org/r/1598/>in Nov-2011 and keeps waiting there...
>    - With these patches, Asterisk+DAHDI is fully dynamic, where we can
>    add/remove channels and spans at run-time without affecting the PBX.
>    - But non of this is committed to trunk :-(
> So with all the multi-year effort to solve this problem, we are still in
> square-one.
> Releasing Asterisk 12 in this state is a major failure in my book.
> Are your customers happy when a single channel failure make the whole PBX
> drop dead? If not, why don't you review those patches?
> Sorry for the not-so-happy tone, but...

Hi Oron!

So, I'm sorry no one has reviewed Tzafrir's code. It's never good when a
patch is written, gets put up on Review Board, is reviewed and updated, but
then don't receive any additional feedback. Sometimes folks in the
developer community just need a poke in #asterisk-dev or on the
asterisk-dev mailing list to remind them to look at a particular patch -
particularly when it may be in an area of Asterisk that they aren't
personally familiar with. I can certainly ask someone to look at the
patches to try and get them moving along again.

As far as Asterisk 12 goes:

* Since the patch is up on Review Board - and Tzafrir is certainly engaged
on the patches! - I don't see any problem with working to get these patches
in for Asterisk 12.
* That being said, we set priorities for Asterisk 12 almost a year ago -
and we're now roughly three weeks out from feature freeze. If this
particular problem was mentioned at AstriDevCon, it certainly isn't in my
notes, which have been up on the wiki for quite some time and were
distributed via the asterisk-dev list - nor is it in the notes for the
AstriDevCon for Asterisk 11, nor the notes for the AstriDevCon for Asterisk
10. In the future, if you want to make sure that something is "on the
radar" for the Asterisk project, it would be good to bring it up in that
meeting so that the entire development community is aware of the feature
and can discuss making it a priority for the upcoming version.



Matthew Jordan
Digium, Inc. | Engineering Manager
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
Check us out at: http://digium.com & http://asterisk.org
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