Sunday, March 5, 2017

Vote disk Maintenance Operations

In this post, I will demonstrate how to add/delete votedisk. From 11.2, votedisk can be stored on either ASM diskgroup.

Before starting please ensure number for failure groups in your diskgroup. Below are the guideline on numbers :-

For Voting disks (never use even number of voting disks):
External redundancy requires minimum of 1 voting disk (or 1 failure group)
Normal redundancy requires minimum of 3 voting disks (or 3 failure group)
High redundancy requires minimum of 5 voting disks (or 5 failure group)

Insufficient failure group in respect of redundancy requirement could cause voting disk creation failure. For example: ORA-15274: Not enough failgroups (3) to create voting files.

For 11.2+, it is no longer required to back up the voting disk. The voting disk data is automatically backed up in OCR as part of any configuration change. The voting disk files are backed up automatically by Oracle Clusterware if the contents of the files have changed in the following ways:

1. Configuration parameters, for example misscount, have been added or modified

2. After performing voting disk add or delete operations
The voting disk contents are restored from a backup automatically when a new voting disk is added or replaced.
The following commands can only be executed when Grid Infrastructure is running. As grid user:-

To add a Voting Disk :-

When votedisk is on ASM diskgroup, no add option available.
The number of votedisk is determined by the diskgroup redundancy. If more copies of votedisks are desired, one can move votedisk to a diskgroup with higher redundancy. 

Scenario :- we are moving vote disk from +DATA(external redundancy) to NORM1(normal redundancy)

[oracle@rac1 ~]$ crsctl query css votedisk

##  STATE    File Universal Id                File Name Disk group
--  -----    -----------------                --------- ---------
 1. ONLINE   8aa71e8567f14f0cbff4b65799421c70 (ORCL:DISK1) [DATA]
Located 1 voting disk(s).

[oracle@rac1 ~]$ crsctl replace votedisk +NORM1
Successful addition of voting disk ac26b4fe2ad44ffdbfc005cf2a4b8f88.
Successful addition of voting disk 5250663c255b4f0fbf4d7aa53b09c65b.
Successful addition of voting disk 8911e608578a4f21bfa326a61c6f1706.
Successful deletion of voting disk 8aa71e8567f14f0cbff4b65799421c70.
Successfully replaced voting disk group with +NORM1.
CRS-4266: Voting file(s) successfully replaced

[oracle@rac1 ~]$ crsctl query css votedisk

##  STATE    File Universal Id                File Name Disk group
--  -----    -----------------                --------- ---------
 1. ONLINE   ac26b4fe2ad44ffdbfc005cf2a4b8f88 (ORCL:DISK5) [NORM1]
 2. ONLINE   5250663c255b4f0fbf4d7aa53b09c65b (ORCL:DISK6) [NORM1]
 3. ONLINE   8911e608578a4f21bfa326a61c6f1706 (ORCL:DISK7) [NORM1]
Located 3 voting disk(s).

If a votedisk is removed from a normal or high redundancy diskgroup for abnormal reason, it can be added back using:
alter diskgroup <vote diskgroup name> add disk '</path/name>' force;

To delete a Voting Disk :-

When votedisk is on ASM, no delete option available, one can only replace the existing votedisk group with another ASM diskgroup

In this blog i'm just sharing the steps. Will share some theoretical concepts very soon...!!!

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