Automatic Storage Management (ASM)

45.1 Concepts

A volume manager and cluster file system built for Oracle files. It stripes (SAME) and mirrors across disks.

Part of Grid Infrastructure (also contains Oracle Restart and Clusterware).

ASM instance (+ASM), disk groups (+DATA, +RECO/+FRA), ASM disks, failure groups, AU size.

Redundancy: EXTERNAL (no mirroring), NORMAL (2-way), HIGH (3-way), FLEX / EXTENDED.

45.2 Management

Disk discovery and ASMLib / ASM Filter Driver (AFD). ACFS (general-purpose cluster file system), ASM proxy instance, Flex ASM.

-- Connected to +ASM as SYSASM
CREATE DISKGROUP data NORMAL REDUNDANCY
  FAILGROUP fg1 DISK '/dev/oracleasm/disk1' FAILGROUP fg2 DISK '/dev/oracleasm/disk2'
  ATTRIBUTE 'au_size' = '4M', 'compatible.asm' = '19.0', 'compatible.rdbms' = '19.0';
ALTER DISKGROUP data ADD DISK '/dev/oracleasm/disk3' REBALANCE POWER 8;
ALTER DISKGROUP data DROP DISK data_0002;
SELECT name, state, type, total_mb, free_mb FROM v$asm_diskgroup;
SELECT * FROM v$asm_operation;   -- rebalance progress

asmcmd lsdg
asmcmd ls +DATA/ORCL/DATAFILE
asmcmd cp +DATA/ORCL/... /tmp/