What is a Diskgroup?
A disk group consists of a grouping of disks that are managed together as a unit. These disks are referred to as ASM disks. An ASM disk can be a disk device, a partition, or a network-attached file.
How do I dismount a Diskgroup?
When you want to mount or dismount disk groups manually, use the ALTER DISKGROUP… MOUNT or ALTER DISKGROUP… DISMOUNT statement. You can mount or dismount disk groups by name, or specify ALL .
How do you check ASM Diskgroup is mounted or not?
select group_number, name, state, type from v$asm_diskgroup;
- To check the asm instance is connected and running:
- To check the asm disks and their status:
- MISSING – Automatic Storage Management metadata indicates that the disk is known to be part of the Automatic Storage Management disk group, but no disk in the storage.
What is ASM rebalancing?
Dynamic Storage Configuration. ASM enables you to change the storage configuration without having to take the database offline. It automatically rebalances—redistributes file data evenly across all the disks of the disk group—after you add disks to or drop disks from a disk group.
What is ASM Diskgroup?
ASM Diskgroups. The main components of ASM are diskgroups, each of which comprise of several physical disks that are controlled as a single unit. The physical disks are known as ASM disks, while the files that reside on the disks are known as ASM files.
What is ASM volume?
ASM volumes are created within an ASM disk group and are used in conjunction with the volume driver for general purpose or ASM cluster file systems. A volume can take up all or part of a single disk group, but it can exist in only one disk group. However, a disk group can contain many volumes, space permitting.
How do I mount a data Diskgroup in ASM?
Manage ASM Disk and Diskgroup information in Oracle
- Check the Size and free space in ASM Disks. set pagesize 200.
- Check the Size and free space in ASM Diskgroup.
- Check the ASM Disk stats.
- Mount and Dismount ASM Disk group.
- Drop the ASM Disk.
- Monitor the Rebalance operation.
- Drop ASM Disgroup.
- Create ASM Disk in Linux.
How do I drop a Diskgroup in ASM?
- Check the ASM Diskgroup. $sqlplus / as sysasm. set lines 999; col diskgroup for a15. col diskname for a15. col path for a35.
- Drop ASM diskgroup. $sqlplus / as sysasm. SQL> DROP DISKGROUP ORA_DATA INCLUDING CONTENTS;
- Check the disk dropped from from ASM Diskgroup.
What is Disk_repair_time in ASM?
In other words, the DISK_REPAIR_TIME value is the acceptable time of duration during you need to fix the failure. This setting is also the countdown timer of ASM to drop the disk(s) that have been taken offline. The default setting for DISK_REPAIR_TIME is 3.6 hours.
How do you rebalance Diskgroup in ASM?
You can manually rebalance the files in a disk group using the REBALANCE clause of the ALTER DISKGROUP statement. This would normally not be required, because Oracle ASM automatically rebalances disk groups when their configuration changes.
What is redundancy in ASM?
ASM allows NORMAL redundancy, in which a diskgroup is composed of two failgroups, or HIGH redundancy, in which a diskgroup is composed of three failgroups.
How do I create a Diskgroup in ASM?
- Create ASM disk. Get the Lun name from storage team. Lun Name – /dev/sda1.
- Check the ASM Disks, Check the newly added disk, $sudo oracleasm listdisks.
- Create the ASM Diskgroup. $sqlplus / as sysasm.
- Check the newly added disk in ASM Diskgroup.
Why can’t I dismount a disk group that contains open files?
If you try to dismount a disk group that contains open files, the statement fails, unless you also specify the FORCE clause. In a clustered Oracle ASM environment in RESTRICTED mode, a disk group is mounted in single-instance exclusive mode. No other Oracle ASM instance in that cluster can mount that disk group.
How are disk groups mounted and dismounted in Oracle ASM?
Disk groups that are specified in the ASM_DISKGROUPS initialization parameter are mounted automatically at Oracle ASM instance startup. This process makes the disk groups available to all database instances running on the same node as Oracle ASM. The disk groups are dismounted at Oracle ASM instance shutdown.
How do I mount a disk group when there are missing disks?
Use the FORCE option to mount a disk group when there are missing disks or missing failure groups. The FORCE option corrects configuration errors, such as incorrect values for ASM_DISKSTRING, without incurring unnecessary rebalance operations.
What is a disk group number and how is it selected?
When a disk group is mounted, a disk group number is chosen. This number may change across disk group mounts. A disk group number is not recorded in any persistent structure, but the current value can be viewed in the GROUP_NUMBER column of the V$ASM views.