On 08/09/16 23:07, Clive Menzies wrote:

We've suffered a series of seemingly disconnect problems on 4 machines since upgrading jessie on Monday:
This nightmare of expanding problems has been going on for three days, since Monday afternoon. Never before have I questioned the decision to base our business (and our lives) on Debian and I remain a firm advocate. I also recognise that over successive releases, accommodating a plethora of configurations becomes harder and that at some point a step changes in the foundations of the system are required. I'm presuming that the transition to systemd from sysv-init was an essential step and understand that backwards compatibility becomes more challenging as time goes on.

Whether this systemd transition is related to the remote connectivity with the servers and the samba issue, I don't know but this number of seemingly random but mission critical series of problems has shaken our confidence.

Apologies if this sounds like a complaint, it's not. It is a concern, which someone may be able to allay, that Debian is not as rock solid as it was.
We've reinstalled all 4 servers and after customising the latest .conf files for dovecot, samba and rsyncd, everything is now communicating as required. Phew!

In retrospect, our practice of keeping our customised .conf files through successive upgrades was probably a mistake. Backwards compatibility worked fine for years, and then suddenly it didn't on a routine upgrade (not a stable transition or point release). In future, we'll accept the maintainer's .conf and customise as necessary. It may add to the time for significant upgrades but should save us a similar episode in future.

This hasn't destroyed our confidence in Debian and I recognise that my lack of knowledge and previous neglect are probably the root causes of our recent problems. It does, however, beg the question: should there be something in the installation warnings to emphasise the risks of keeping old conf files?

If this episode has done anything, it's greatly improved our understanding of what's going on "under the bonnet". Hitherto, we've worked on the basis of: if it ain't broke, don't mess with it.

Finally, the systemd tools make monitoring and understanding where problems arise much easier. In this context, we've one minor wrinkle outstanding. After reboot:/
$ sudo systemctl --all status/
gives: /Warning: Unit file changed on disk, 'systemctl daemon-reload' recommended.

//$ sudo //systemctl daemon-reload /
fixes it but it would be good to prevent it in the first place.



Clive Menzies

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