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Joe --
Sorry for responding to an old thread -- I just noticed it now.
> the other one is ldirectord.
The last time I checked, ldirectord was more suited for HTTP-only
providers, yesno?
> Want to tell me what you don't like about mon? I'll put it in the HOWTO
> to help other unsuspecting travellers if nothing else.
I really think this is a matter of opinion.
> I use mon, but it has no way of merging failure info. If a node fails you
> get notices from all the services that died along with the node
Are you sure this isn't just a configuration issue?
If you are careful, you can avoid this. For example, it is easy to write
a simple script which runs every monitor you want. This way only one message
is sent when one or more services goes down on a system. The downside to
this is that the entire system goes down when one service fails.
There are other alternatives to make sure you only receive one notice
when a service goes down, but are you sure you would want that? What if
genuinely two services on a system go down but all the other services are
up? I, personally, would want to receive notifications about both services.
Ideally, what you want is a dependency setup. Most other system monitors
(like the popular "WhatsUp" by IpSwitch (or whatever they call themselves
now)) that will only send you one notification if, for example, the ICMP
monitor reports a failure. This functionality can also be easily built into
the monitors.
So the way I see it, mon is fine, but sometimes the monitors one uses
with mon might need a little work. Mon is nice because it is so versatile
and pluggable. It's modular and doesn't lock one into using some proprietary
scripting language to build monitors. Of course, this also makes it very
slow. :(
All of these things can be improved, of course, in a number of ways
which can be addressed and fixed one by one. However, most people have gone
with ldirectord so mon, in this application, seems to really have been
forgotten. :(
I use mon and have been using it for a long time now and have no real
problems with it. My biggest problem was that both of my redundant
linuxdirectors notified me when things went down. I just wrote in a simple
addition to the mailto script which figured out if the machine on which it
was running was a master and if and ONLY if it was, it would send a message.
That solved that problem.
mon can be a particularly powerful tool, I think.
Now you should note that I have a made quite a few changes to mon to
make it more LinuxDirector-friendly. Rather than configuring mon through its
configuration scripts, I configure mon and ipvsadm all through some very
simple configuration files I use that control both equally. This required
quite a bit of hacking inside mon to get it to dynamically create
configuration data, but all of this modification isn't needed for the
average LVS-admin.
Abstract: mon ain't really that bad. If ldirectord was everything I'd
want it to be, it'd be mon.... consequence: I use mon. :)
At least that's my two cents.
All the best --
Ted
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