Requests send toFusionStorage return 503 error code , the problemlasted for dozens of seconds in a single node.

1. Check the service log in aFusionStorage node, we found the log shows that the requests exceeds the maxrequest threshold at that time.

2.Every FusionStorage node canprocess 1000 requests at the same time, if requests exceed the threshold, newrequest will return 503 directly, which means the current service node is toobusy to process.

【Root Cause】:

When using FusionStorage’s DNSto resolve domain name to a IP, the DNS will return a random service IP toclient, and it is a pseudorandom IP selection, the DNS can’t do a load-balanceIP selection. So, when request numbers growing up to a very high level, therequests may point to only a few nodes and  these nodes request number may exceed thethreshold in a brief period.

Considering using the LVS whichis a real load-balance solution, and then config the DNS resolve to the LVSfloat IP to balance all the service requests.