"Paul B. Henson" henson@acm.org schrieb am 16.02.2022 um 04:10 in Nachricht
114ede97-a51b-5fbd-0613-47208945aa88@acm.org:
...
I can certainly just throw memory at it and hope the problem goes away.
Remember there are some classic tools like sar, vmstat, iostat, etc. to display or store some interesting information about what the OS is doing. Maybe youngsters will prefer something like "watch cat /proc/meminfo" to see live how RAM is shuffled around.
But based on the observations when it occurs it does not feel like just a memory problem. The last time it happened I pulled the node out of the load balancer so nothing else was poking at it and the test query was still taking more than 30 seconds.
iotop is another nice utility.
I'm going to bump the production nodes up to 4G, which should be more than enough to run the OS and always have the entire database plus all indexes in memory. I will keep my fingers crossed this problem just goes away, but if it doesn't, what else can I do when it occurs to help track it down?
You didn't tell what hypervisor you are using, bu tdid you know that Xen PVMs support "memory hotplugging"? You can add RAM while the OS is running (also works with CPUs), but it has to be prepared in config...
Regards, Ulrich