Heya,

Since we're having Fun Times with Solaris while all locked-down, I'll add 
one that popped up over the weekend.

Host is running 11.3/x86. Good performance, normally stable and running a 
near-idle CPU burn as this is primarily a storage host with moderate 
demands (only writing about 2MB/sec average over time apart from bursts).

In an absolute instant with no warning, CPU usages starts running high. 
Here's a graph from Zabbix: 
http://mexico.purplecow.org/p/data/images/7/7.png

Simple operations like an ssh connection to the host are very sluggish. 
Normally low-burning processes are now consuming a real % of CPU. For 
example, nmbd was burning 5% according to prstat.

The kernel process for running the main data zpool was now burning about 
50% of the user time on the host and I/O was taking a long time to dequeue 
to disk, leading to measurable performance changes on client systems.

FMA is reporting no activity and there is nothing in any logs, including 
the non-default logfile that takes debug.* from syslog.

DRAC reports system temperature of 23 degrees and CPU temperature of 42 
degrees, fluctuating only mildly.

Symptom-wise, for all intents and purposes it looked like the CPU had 
throttled down to some insanely slow speed and was dragging everything 
through the mud, now running up at 90% systime just servicing interrupts 
and ZFS.

Nothing interesting in lockstat. Nothing interesting in intrstat other 
than the sheer % of CPU burned servicing mpt_sas and qlt.

After an extended period of trying to work out the root cause, the machine 
was dealt an init 5 (after zpool offline on a number of clients, good 
thing they were mirrored across heads...) and after a very long shutdown 
the machine was re-powered with all symptoms gone.

Ideas?

CPU burn graph including pre-event and post-reboot:
http://mexico.purplecow.org/p/data/images/9/9.png

Graph legend:   blue = user time
                red = sys time
                green = idle

Andre.


-- 
Andre van Eyssen.                  Phone:     +61 417 211 788
mail:     [email protected]      http://andre.purplecow.org
About & Contact:          http://www.purplecow.org/andre.html

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