Couple of questions comes to mind. Are you using EBS for your storage? What’s the average object size?
It would be interesting to enable micro-benchmark and storage-benchmark during these events.
Please see:
and
These should help you track if certain latency spike are occuring.
Also you may want to check on open sockets by running:
sudo lsof|grep `sudo ps aux|grep -v grep|grep -E 'asd|cld'|awk '{print $2}'` 2>/dev/null
Recommend also reading: