Stabbing in the dark, but this sounds like a multipath problem. Perhaps you have 2 or more paths to the storage, and one or more of them is down for some reason, perhaps the hardware itself, perhaps a cable is pulled.... You could look for LEDs in a bad state.

I always find it instructive to reboot such a system and watch what comes up on the console during the startup.


On 9/20/2016 12:29 PM, Joe Landman wrote:
On 09/20/2016 12:21 PM, Lewis Hyatt wrote:

We do not know if it's related, but this same OSS is in a very bad
state, with very high load average (200), very high I/O wait time, and
taking many seconds to respond to each read request, making the array
more or less unusable. That's the problem we are trying to fix.

This sounds like a storage system failure. Queuing up of IOs to drive the load to 200 usually means something is broken elsewhere in the stack at a lower level. Not always ... sometimes you have users who like to write several million/billion small ( < 100 byte ) files.

What does dmesg report? Try to do a pastebin/gist of it, and point it to the list.

Things that come to mind are

a) offlined RAID (most likely): This would explain the user load, and all sorts of strange messages about block devices and file systems in the logs

b) A user DoS against the storage: usually someone writing many tiny files.

There are other possibilities, but these seem more likely.

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