I’m a bit confused by this… Why is it looking for sdc when you only have a file specified? Are there multiple namespaces?
I suspect it might have something to do with using a file… The kernel might be trying to cache things here. While the memory usage is high, what does it drop down to if you run
echo 3 > /proc/sys/vm/drop_caches ?
https://www.aerospike.com/docs/reference/configuration/index.html#direct-files might be a solution, but im not certain