Posted by Riyaj Shamsudeen on May 22, 2012
Let’s first discuss how RAC traffic works before continuing. Environment for the discussion is: 2 node cluster with 8K database block size, UDP protocol is used for cache fusion. (BTW, UDP and RDS protocols are supported in UNIX platform; whereas Windows uses TCP protocol).
UDP protocol, fragmentation, and assembly
UDP Protocol is an higher level protocol stack, and it is implemented over IP Protocol ( UDP/IP). Cache Fusion uses UDP protocol to send packets over the wire (Exadata uses RDS protocol though).
MTU defines the Maximum Transfer Unit of an IP packet. Let us consider an example of MTU set to 1500 in a network interface. One 8K block transfer can not be performed with just one IP packet as the IP packet size (1500 bytes) is less than 8K. So, one transfer of UDP packet of 8K size is fragmented to 6 IP packets and sent over the wire. In the receiving side, those 6 packets are reassembled to create one UDP buffer of size 8K. After the assembly, that UDP buffer is delivered to an UDP port of a UNIX process. Usually, a foreground process will listen on that port to receive the UDP buffer.
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Posted in 11g, Oracle database internals, Performance tuning, Presentations, RAC, video | Tagged: cache fusion mtu, fragmentation and reassembly, gc lost packets, ipfrag_high_thres, ipfrag_low_thres, ipfrag_time, Jumbo frames, MTU, MTU=9000, oracle performance, RAC internals, RAC performance, RAC presentations, RAC training, RAC video, RAC videos, RDS, UDP vs tcp, wireshark | 12 Comments »
Posted by Riyaj Shamsudeen on April 19, 2012
If you are attending Collaborate 2012, you might be interested in my content-rich sessions below :
Session Number: 326
Session Title: SCAN, VIP, HAIP, and other RAC acronyms
Session Date/Time/Room: Tue, Apr 24, 2012 (10:45 AM – 11:45 AM) : Surf C
Session Number: 327
Session Title: Internals and Performance Boot Camp: Truss, pstack, pmap, and more
Session Date/Time/Room: Wed, Apr 25, 2012 (03:00 PM – 04:00 PM) : Palm A
Hope to see you there!
Update: I am uploading presentation files. Presentations are much more recent than the document🙂
Thanks for attending!
Posted in Oracle database internals, Performance tuning, Presentations, RAC | Tagged: collaborate 2012 presentations, haip, pfiles, pmap, pstack, RAC, RAC performance, RAC presentations, scan, semtimedop, strace, truss, vip | 1 Comment »
Posted by Riyaj Shamsudeen on February 10, 2012
I will be leaving to Denver in few days to talk about the following presentations in RMOUG 2012. Stop by and say hello to me if you intend to attend RMOUG training days.
My sessions in RMOUG 2012 are
- Room 402:Session 2: Parallel Execution in RAC – Wednesday 10:45 AM to 11:45AM
- Room 4f: Session 10: Troubleshooting RAC background processes – Thursday 1:30PM to 2:30PM
- Room 4f: Session 11: A kind and Gentle introduction to RAC – Thursday 2:45 PM to 3:45 PM
Hope to see you there.
Posted in Performance tuning, Presentations, RAC | Tagged: oracle performance, pstack, RAC presentations, rmoug | 2 Comments »