When a disk failure
occurs for an ASM disk, behavior of ASM would be different, based on what kind
of redundancy for the diskgroup is in use. If diskgroup has EXTERNAL REDUDANCY,
diskgroup would keep working if you have redundancy at external RAID level. If
there is no RAID at external level, the diskgroup would immediately get dismounted
and disk would need a repair/replaced and then diskgroup might need to be
dropped and re-created, and data on this diskgroup would require recovery.
Oracle Installation guides, Linux Administration tips for DBAs, Performance Tuning tips, Disaster Recovery, RMAN, Dataguard and ORA errors solutions.
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Monday, January 29, 2018
Monday, January 22, 2018
ORA-00845: MEMORY_TARGET not supported on this system
If we face ORA-00845
during database startup, it would mean that /dev/shm file system is not
configured with appropriate value required to start the database instance. We
need to mount /dev/shm with a value that should be equal or more than the value
of memory we want to allocate to all instances/SGAs (ASM as well as database
instances) that would run on this host.
You may find
following type of warning in alert log file.
Monday, January 8, 2018
Slow RMAN Performance for CROSSCHECK and DELETE OBSOLETE
I faced an issue
recently where my CROSSCHECK and DELETE OBSOLETE commands were too much slow to
execute, actually these were hung. The reason for this issue was IP address
change of my NFS server form where a drive was mounted on database server for
backups and backups were being taken on this NFS share. After NFS server’s IP
address change, RMAN would go to check old IP address to search for the
old/obsolete backups when we executed CROSSCHECK and DELETE OBSOLETE commands.