Anyone had a problem with Redis suddenly spiking and then crashing the server? we have had a recurring problem with Magento2. Redis suddenly gets hit with masses of data which makes it unavailable and it eventually crashes.
Did you check dmesg / kern.log, to make sure it didn't get killed by the system OOM killer?
It is also possible, that you set up redis maxmemory to small and are hitting a memory limit inside redis.
If you really are getting hit with lots of data, you can use the monitor command inside redis-cli, to check out the data.