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Load average spikes once an hour

 
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# 8  
Old 04-14-2011
There is a bit more going on that what these snapshots are showing you. If you saw my top during that time, I had a constant iowait around 50-80% despite lfd/md5sum showing significantly less CPU utilization.

I think the root issue is the way the CSF firewall was configured out of the box. Every 3600 seconds (60 minutes), it's doing a "System Integrity Check". Here is what they have to say about it:

Quote:
# System Integrity Checking. This enables lfd to compare md5sums of the
# servers OS binary application files from the time when lfd starts. If the
# md5sum of a monitored file changes an alert is sent. This option is intended
# as an IDS (Intrusion Detection System) and is the last line of detection for
# a possible root compromise.
#
# There will be constant false-positives as the servers OS is updated or
# monitored application binaries are updated. However, unexpected changes
# should be carefully inspected.
#
# Modified files will only be reported via email once.
#
# To enable this feature set the following to the checking interval in seconds
# (a value of 3600 would seem sensible). This option may increase server I/O
# load onto the server as it checks system binaries.
#
# To disable set to "0"
LF_INTEGRITY = Default: 3600
I am going to set it to 0 to see if this solves the immediate problem.

---------- Post updated at 06:04 AM ---------- Previous update was at 05:28 AM ----------

bingo! the iowait for this hour is back to normal levels! I'll keep an eye on it today.
# 9  
Old 04-14-2011
Quote:
Originally Posted by pinga123
I can see its not taking your cpu as much as you are worried it is.
It is just 0.2% of your cpu and you shouldn't be worrying about it.
Low CPU doesn't mean it's not thrashing the disk. In fact low CPU on something with no built-in delays like md5sum probably means it IS thrashing the disk.
# 10  
Old 04-17-2011
Quote:
Originally Posted by Corona688
Low CPU doesn't mean it's not thrashing the disk. In fact low CPU on something with no built-in delays like md5sum probably means it IS thrashing the disk.
Does LOW CPU necessarily has to translate to 'thrashing the disk' I don't that is right? It could be simple IO wait on a NFS!!!
# 11  
Old 04-17-2011
Quote:
Originally Posted by matrixmadhan
Does LOW CPU necessarily has to translate to 'thrashing the disk' I don't that is right?
For something that's not interactive and never sleeps, like md5sum, if it's not pinning the CPU, it's waiting for I/O.
Quote:
It could be simple IO wait on a NFS!!!
Thrashing the network is better how? And that'd still be thrashing someone's disk, if not yours.
 
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