[Freeipa-users] I/O Problems after update to IPA Version RHEL6.4

[natxo asenjo]

On 06/27/2013 09:33 PM, Marc Grimme wrote:
> With heavy load I mean that the ldap process is consuming MUCH more CPU usage then before.
> As you can see from the top screenshot is that I/O Wait is 54.4% and CPU around 50% this is way too much. And this is not good.
> Before it was always around 0-1%.

>> top - 21:09:53 up 6 days,  4:18,  2 users,  load average: 1.73, 1.71, 1.74
>> Tasks: 107 total,   1 running, 106 sleeping,   0 stopped,   0 zombie
>> Cpu0  : 37.5%us,  1.9%sy,  0.0%ni,  0.0%id, 54.4%wa,  0.0%hi,  0.0%si,  6.2%st
>> Mem:   1922724k total,  1547748k used,   374976k free,   133928k buffers
>> Swap:  2064376k total,     1812k used,  2062564k free,   233944k cached
>>
>>     PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>> 32134 dirsrv    20   0 1626m 652m  16m S 35.8 34.8  66:33.38 /usr/sbin/ns-slapd -D /etc/dirsrv/slapd-CL-ATIX -i /var/run/dirsrv/slapd-CL-ATIX.pid -w /var/run/d
>>     912 root      20   0  314m  47m 7220 S  5.3  2.6   0:02.11 /usr/bin/python -E /usr/sbin/ipa-replica-manage list
>>    2012 root      20   0  192m 5280 1536 S  0.3  0.3   3:43.13 /usr/sbin/snmpd -LS0-6d -Lf /dev/null -p /var/run/snmpd.pid
>>       1 root      20   0 21304 1352 1092 S  0.0  0.1   0:06.61 /sbin/init
>>       2 root      20   0     0    0    0 S  0.0  0.0   0:00.00 [kthreadd]

you only have one cpu, and the load it is getting is too much for it.
With one cpu, you should see a load under 1, with 2, under 2, etc. For
an explanation on what you are seeing there, take a look at this:

http://en.wikipedia.org/wiki/Load_%28computing%29#Unix-style_load_calculation

When the cpu is in i/o wait state that means the processor has to
wait until it gets data for processing. It *usually* is storage and/or
network contention.

A few questions to get you troubleshooting off the top of my head:

Is this a vm or a real hardware server? What are the specs? Is your 
network being used now more heavily than before the upgrade?

Where is the storage? DAS, NAS, SAN? Is it enterprise grade storage,
slow sata disks, fast sas disks? If network storage (nfs, iscsi): what
speed is your storage network switching layer? Is it isolated from the
normal network switches? Fiber channel? What speed are the switches?

If it is a vm: are the disks properly aligned to the specs of your
storage vendor?

Be aware that load tuning is a very complicated business. If this is a
vm and you can allocate another cpu to it, you could try that. But if
the underlying host hardware is memory/cpu/disk/network constrained, it
will not help much. Lots of variables to take into account, I am afraid

-- 
groet,
natxo