Hourly spikes on load

Hello,

We've just put two Open-E systems with iSCSI failover in (semi) production, the actual load of the running servers is really low right now. However, when I look at both our systems, there is an hourly spike visible in the load graph. Is there some (nice) running task every hour which causes this spike? The second system is running as secondary and doesn't seem to spike at the exact some moment, but also hourly.

Here an example of what this look like:

http://img192.imageshack.us/img192/1050/loadday.png

Any ideas?

Thanks in advance.

Joost.

Quote:

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Originally Posted by jvandenbroek

Hello,

We've just put two Open-E systems with iSCSI failover in (semi) production, the actual load of the running servers is really low right now. However, when I look at both our systems, there is an hourly spike visible in the load graph.

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Joost,

Given that the "spike" represents an increase to little more 1% CPU utilitilization, I think you are reading way too much into it. Think of it as a comatose patient who every so often twitches to show that there is some brain activity taking place...

Quote:

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Originally Posted by SeanLeyne

Joost,

Given that the "spike" represents an increase to little more 1% CPU utilitilization, I think you are reading way too much into it. Think of it as a comatose patient who every so often twitches to show that there is some brain activity taking place...

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Hi,

where do you take the 1% from? If I'm not lacking coffee, the diagram shows load not CPU utilization.

So the sporadic increase to above 1.0 means that one CPU (more precise: core) is fully loaded. If this were a single-core machine, this would be rather important.

As to the source of the spikes: I don't have my load graphics at hand right now, but don't recall seeing these on a DSS server without client load. OTOH, I do see such spikes whenever some client accesses ie NFS volumes. So when you have periodic client access (ie backup software scanning for modified files, batch processing or alike) I'd expect to see such spikes.

You might want to compare against the CPU utilization chart to see whether the load is caused by actively doing something on the DSS server (increase in CPU util - user or system space - which could be the handling of iSCSI packets) or by I/O (I/O waits growing during the load peaks). Also you can compare to the network I/O - if you see traffic increase between server and client, then obviously those are causing the load. If it's just traffic between the servers, then it could be some replication action.

Regards,
Jens

PS: May be bean counting, but II don't see *hourly* spikes - it's more like 45 minutes. This may be important in identifying the periodic processes.

Hi Jens,

Thanks, indeed this diagram is't about CPU utilization. All other diagrams aren't showing any peaks, CPU usage is even scarely low (1% user, 1% nice, 1% system over the whole day, which would make me think the graphing is broken). Both systems are identical and have an Adaptec 5805 controller, maybe that has something to do with it.. Not sure, I'll keep an eye on it, thanks for the suggestions.

Hi jvandenbroek,

I have these spikes too, my graph looks almost identical to yours.
My RAID card is an LSI Megaraid. Doesn't seem to be causing me any issues though.

Did you get any further information?

Cheers,
Jon