LSM Overview

The logical storage manager (LSM) is used to manage storage containers or storage pools referred to as logical volumes.

LSM is not a requirement for Oracle9 i RAC, but when used it can improve overall I/O performance without manual file placement. Using LSM to stripe multiple raidsets can improve overall Oracle I/O performance. The Oracle database files will be balanced across all members in the stripe set.

Why Use LSM?

• Software striping of hardware raidsets for improved I/O throughput

• Disk consolidation, reducing number of independent disks or raidsets

• Requirements for large filesystem support beyond size of single raidset

• Software mirroring and hardware RAID for highest data availability

Some Configurations Will Not Require the Use of LSM

• Few disks in configuration (only 2 3 disks)

• Don't want extra administration step and management

• May want to use AdvFS striping

• Oracle database files will be manually placed on disks

S.A.M.E (Stripe and Mirror Everything)

For some configurations Oracle and Compaq recommend "S.A.M.E." All disks used in the database are hardware mirrored and then striped together using LSM. The mirroring and striping is also referred to as RAID 10. A few things to remember when using RAID 10:

• Mirrored storage can become costly

• Weigh redundancy and performance verses cost

• Keep volumes to a manageable size (400GB, 800GB, 1000GB, etc.)

• Set the proper stripe size using LSM

• Stripe disks from multiple controllers for best performance and availability

S.A.R.E. (Stripe and Raid Everything)

The S.A.R.E.