Tuesday, April 7, 2015

LPAR and Oracle Database

What is LPAR?

LPAR stands for Logical Partitioning and it's a feature of IBM's operating system AIX (Also available in Linux). By abstracting all the physical devices in a system, LPAR creates a virtualized computing environment.

In a server; the processor, memory, and storage are divided into multiple sets. Each set in a server consist of resources like processor, memory and storage. Each set is called as LPAR.

One server can have many LPARs operating at the same time. These LPARs communicate with each other as if they are on separate machines.

What is DLPAR?

DLPAR stands for Dynamic Logical Partitioning and with DLPAR the LPARs can be configured dynamically without restart. With DLPAR, memory, CPU and storage can be moved between LPARs on the fly.

What is HMC?

HMC stands for Hardware Management Console. The Hardware Management Console (HMC) is interface which is used to manage the LPARs. Its Java based and can be used to manage many systems.

If LPAR is in shared processor mode, without the following fix, LPAR may see excessive CPu usage: 

IV01111 AIX 6.1 TL05 if before SP08 (fixed in SP08)
IV06197 AIX 6.1 TL06 if before SP07 (fixed in SP07)
IV10172 AIX 6.1 TL07 if before SP02 (fixed in SP02)
IV09133 AIX 7.1 TL00 if before SP05 (fixed in SP05)
IV10484 AIX 7.1 TL01 if before SP02 (fixed in SP02)

This problem can effect POWER7 systems running any level of Ax720 firmware prior to Ax720_101. But it is recommended to update to the latest available firmware. If required, AIX and Firmware fixes can be obtained from IBM Support Fix Central:

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