gc cr block lost / gc current block lost

TOP 5 Timed Events - gc cr block lost / gc current block lost

Global cache lost blocks statistics ("gc cr block lost" and/or "gc current block lost") for each node in the cluster as well as aggregate statistics for the cluster represent a problem or inefficiencies in packet processing for the interconnect traffic. These statistics should be monitored and evaluated regularly to guarantee efficient interconnect Global Cache and Enqueue Service (GCS/GES) and cluster processing. Any block loss indicates a problem in network packet processing and should be investigated.

The vast majority of escalations attributed to RDBMS global cache lost blocks can be directly related to faulty or mis-configured interconnects. “lost blocks” at the RDBMS level, responsible for 64% of escalations.

Misconfigured or Faulty Interconnect Can Cause: 

•          Dropped packets/fragments

•          Buffer overflows

•          Packet reassembly failures or timeouts

•          Ethernet Flow control kicks in

•          TX/RX errors

 “Lost Blocks”: NIC Receive Errors

Db_block_size = 8K

ifconfig –a:

eth0 Link encap:Ethernet  HWaddr 00:0B:DB:4B:A2:04

            inet addr:130.35.25.110  Bcast:130.35.27.255  Mask:255.255.252.0

            UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

            RX packets:21721236 errors:135 dropped:0 overruns:0 frame:95

            TX packets:273120 errors:0 dropped:0 overruns:0 carrier:0

“Lost Blocks”: IP Packet Reassembly Failures

            netstat –s

Ip:
   84884742 total packets received
   …

  1201 fragments dropped after timeout
   …
   3384 packet reassembles failed

Detailed Explanation of the this wait event can be found at Metalink - gc block lost diagnostics [ID 563566.1]