[Info-vax] openvms and xterm

[Dan Cross]

In article <v07268$hqd$1 at panix2.panix.com>,
Scott Dorsey <kludge at panix.com> wrote:
>Grant Taylor  <gtaylor at tnetconsulting.net> wrote:
>>
>>I hear people say that systemd and smf are service management things and 
>>that traditional SysV style init scripts aren't.  But they never explain 
>>why the former is and the latter isn't.
>
>The one thing that smf and systemd have is the ability to watch a process
>and restart it if it crashes.  Many people find this very important, although
>personally I suspect that if your service is crashing a lot that you should
>fix it rather than rely on something else to restart it.

The thing is, when you're working at scale, managing services
across tens of thousands of machines, you quickly discover that
shit happens.  Things sometimes crash randomly; often this is
due to a bug, but sometimes it's just because the OOM killer got
greedy due to the delayed effects of a poor scheduling decision,
or there was a dip on one of the voltage rails and a DIMM lost a
bit, or a job landed on a machine that's got some latent
hardware fault and it just happened to wiggle things in just the
right way so that a 1 turned into a 0 (or vice versa), or any
number of other things that may or may not have anything to do
with the service itself.

Again, at scale, this can happen thousands of times a day.  You
can't reasonably track them all down.  Often, the only thing you
can do is just restart the service and log it; eventually, some
poor SRE may notice a pattern in the failures and get it fixed.
Or not.

>Something else that they do provide is automated management of dependencies
>to start everything in order without the admin having to manually set the
>order of execution up.  This can be a benefit and if done well can also speed
>boot times, but I am not sure that this is necessary to call a startup
>mechanism a service manager.
>
>>I was genuinely trying to learn something.
>
>This is not likely to be a thread in which anyone will learn much, I am sorry
>to say.

That's a shame.

	- Dan C.