Expert Oracle Exadata - Parent Directory

CHAPTER 1 WHAT IS EXADATA? Kevin Says: RDS has indeed been around for quite some time, although not with the Exadata use case in mind.The history of RDS goes back to the partnering between SilverStorm (acquired by Qlogic Corporation) and Oracle toaddress the requirements for low latency and high bandwidth placed upon the Real Application Clusters nodeinterconnect (via libskgxp) for DLM lock traffic and, to a lesser degree, for Parallel Query data shipping. The lattermodel was first proven by a 1TB scale TPC-H conducted with Oracle Database 10g on the now defunctPANTASystems platform. Later Oracle aligned itself more closely with Mellanox.This history lesson touches on an important point. iDB is based on libskgxp, which enjoyed many years ofhardening in its role of interconnect library dating back to the first phase of the Cache Fusion feature in Oracle8i.The ability to leverage a tried and true technology like libskgxp came in handy during the move to take SAGE tomarket.It is important to understand that no storage devices are directly presented to the operating systemson the database servers. Therefore, there are no operating-system calls to open files, read blocks fromthem, or the other usual tasks. This also means that standard operating-system utilities like iostat willnot be useful in monitoring your database servers, because the processes running there will not beissuing I/O calls to the database files. Here’s some output that illustrates this fact:KSO@SANDBOX1> @whoamiUSERNAME SID SERIAL# PREV_HASH_VALUE SCHEMANAME OS_PID--------------- ---------- ---------- --------------- ---------- -------KSO 689 771 2334772408 KSO 23922KSO@SANDBOX1> select /* avgskew3.sql */ avg(pk_col) from kso.skew3 a where col1 > 0;...> strace -cp 23922Process 23922 attached - interrupt to quitProcess 23922 detached% time seconds usecs/call calls errors syscall------ ----------- ----------- --------- --------- ----------------49.75 0.004690 0 10902 5451 setsockopt29.27 0.002759 0 6365 poll11.30 0.001065 0 5487 sendmsg9.60 0.000905 0 15328 4297 recvmsg0.08 0.000008 1 16 fcntl0.00 0.000000 0 59 read0.00 0.000000 0 3 write0.00 0.000000 0 32 12 open0.00 0.000000 0 20 close14