Large Installation

[Andreas Ericsson]

On 06/11/2010 04:08 PM, Scott Ward wrote:
> How does Merlin compare with NDO in terms of resource usage?
> 

merlin is fairly lightweight. What little memory its uses resides
primarily on the stack and fits well inside the stack of 1MiB.

Here's the output of "ps wwaux | grep merlin" on a master system
with two connected pollers. As you can see, "grep" consumes more
memory than the merlin daemon does. This is with debug symbols
compiled in btw, so it will be roughly half that when it's built
for production.
root     12286  0.0  0.2  61116   660 pts/0    R+   17:29   0:00 grep -i merlin
root     23236  0.0  0.7  50572  1856 ?        S    13:56   0:01 /opt/monitor/op5/merlin/merlind -c /opt/monitor/op5/merlin/merlin.conf


As for CPU usage, it's definitely more lightweight than NDO. A
typical merlin daemon will basically idle away most of its time.
It's the database that does the heavy lifting after all, so it's
not that hard to make merlin itself lean and extremely quick.

As for storage-space, it doesn't use nearly as much as ndoutils
does, since we don't store the entire log and all status updates
in the database, but only the current status and statechanges,
where a statechange is defined as "either the state has changed,
or the object went from soft to hard state", which is basically
all we need to make reports look good. Since the logfiles are
already partitioned by date, it was deemed a lot easier to write
a super-fast parser for those instead and make that parser able
to display html output. This is the helper we use in ninja, and
it's working extremely well, showing interesting logdata in a
matter of seconds.

It will grow over time ofcourse, but while NDOUtils' database
can grow to tens of gigabytes in a matter of months for a large
network, merlin stores about 500MiB for a whole year for the same
size network.

-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Considering the successes of the wars on alcohol, poverty, drugs and
terror, I think we should give some serious thought to declaring war
on peace.

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