Video on Client Side Failover in RAC

 I've posted a new video demonstrating Client Side Failover defined by the tnsnames.ora file

Video on Host Names, SCAN and IP Addresses

 I've posted a new Video on Host Names, SCAN and Virtual IPs in RAC (using a 2-node 19c Cluster)

Grid Infrastructure --- OCR and Voting Disks Location at Installation

 In Oracle Grid Infrastructure, the OCR (Oracle Cluster Registry) and Voting "Disks" must be on Shared Storage accessible by all the nodes of the Cluster.  Typically, these are on ASM.

In ASM, a DiskGroup is created for the disks that hold the OCR.  

Normally, an ASM DiskGroup may use External Redundancy (Mirroring or other protection against Physical Disk or LUN failure is provided by the underlying Storage) or Normal Redundancy (Two-Way Mirroring, i.e. two Disks or LUN devices) or High Redundancy (Three-Way Mirroring with three Disks).

However, for the OCR and Voting "Disks" (i.e. Voting File), Normal Redundancy requires three Disks or LUN devices where three Voting Files and one OCR (Primary and Secondary copy) are created.  High Redundancy requires five Disks or LUN devices where five Voting Files and once OCR (with one Primary and two Secondary copies) are created.

In Test or Lab environments, you might have created your OCR/Vote DiskGroup on ASM storage with External Redundancy so as to not have to provision 3 or 5 disks.

However, in the 19c Lab environment with 2 Virtual Box VMs that I recently built on my Home PC, I created 5 ASM Disks of 2GB each (using ASMLib instead of udev persistent naming)  to hold the OCR + VOTE DiskGroup.  I then selected High Redundancy for the consequent DiskGroup.

This is the Installer Screen :

This is the subsequent output from running root.sh from the Grid ORACLE_HOME towards the end of the installation :

[datetime] CLSRSC-482: Running command: '/u01/app/grid/product/19.3/bin/ocrconfig -upgrade grid grid'

CRS-4256: Updating the profile

Successful addition of voting disk 6c3ea5fbf0254fd5bfd489fc5c674409.

Successful addition of voting disk ff3b9da031064fccbfab4b57933f12e1.

Successful addition of voting disk 44e50015bcf24f7cbfc1b9348fdbe568.

Successful addition of voting disk de64da366c164f5cbfba2761df5948d5.

Successful addition of voting disk 4485ff5940384f85bf524a81090c6bd8.

Successfully replaced voting disk group with +OCR_VOTE.

CRS-4256: Updating the profile

CRS-4266: Voting file(s) successfully replaced

##  STATE    File Universal Id                File Name Disk group

--  -----    -----------------                --------- ---------

 1. ONLINE   6c3ea5fbf0254fd5bfd489fc5c674409 (/dev/oracleasm/disks/OCR_VOTE_DISK_1) [OCR_VOTE]

 2. ONLINE   ff3b9da031064fccbfab4b57933f12e1 (/dev/oracleasm/disks/OCR_VOTE_DISK_2) [OCR_VOTE]

 3. ONLINE   44e50015bcf24f7cbfc1b9348fdbe568 (/dev/oracleasm/disks/OCR_VOTE_DISK_3) [OCR_VOTE]

 4. ONLINE   de64da366c164f5cbfba2761df5948d5 (/dev/oracleasm/disks/OCR_VOTE_DISK_4) [OCR_VOTE]

 5. ONLINE   4485ff5940384f85bf524a81090c6bd8 (/dev/oracleasm/disks/OCR_VOTE_DISK_5) [OCR_VOTE]

Located 5 voting disk(s).

Thus it did create 5 Voting "Disks" (Voting Files).

After the installation is completed, I verified this again  

from the first node "srv1":

[root@srv1 ~]# ocrcheck

Status of Oracle Cluster Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      84232

         Available space (kbytes) :     407452

         ID                       : 1183403784

         Device/File Name         :  +OCR_VOTE

                                    Device/File integrity check succeeded

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

         Cluster registry integrity check succeeded

         Logical corruption check succeeded

[root@srv1 ~]# crsctl query css votedisk

##  STATE    File Universal Id                File Name Disk group

--  -----    -----------------                --------- ---------

 1. ONLINE   6c3ea5fbf0254fd5bfd489fc5c674409 (/dev/oracleasm/disks/OCR_VOTE_DISK_1) [OCR_VOTE]

 2. ONLINE   ff3b9da031064fccbfab4b57933f12e1 (/dev/oracleasm/disks/OCR_VOTE_DISK_2) [OCR_VOTE]

 3. ONLINE   44e50015bcf24f7cbfc1b9348fdbe568 (/dev/oracleasm/disks/OCR_VOTE_DISK_3) [OCR_VOTE]

 4. ONLINE   de64da366c164f5cbfba2761df5948d5 (/dev/oracleasm/disks/OCR_VOTE_DISK_4) [OCR_VOTE]

 5. ONLINE   4485ff5940384f85bf524a81090c6bd8 (/dev/oracleasm/disks/OCR_VOTE_DISK_5) [OCR_VOTE]

Located 5 voting disk(s).

[root@srv1 ~]#

and from the second node "srv2" :

[root@srv2 ~]# ocrcheck

Status of Oracle Cluster Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      84232

         Available space (kbytes) :     407452

         ID                       : 1183403784

         Device/File Name         :  +OCR_VOTE

                                    Device/File integrity check succeeded

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

         Cluster registry integrity check succeeded

         Logical corruption check succeeded

[root@srv2 ~]# crsctl query css votedisk

##  STATE    File Universal Id                File Name Disk group

--  -----    -----------------                --------- ---------

 1. ONLINE   6c3ea5fbf0254fd5bfd489fc5c674409 (/dev/oracleasm/disks/OCR_VOTE_DISK_1) [OCR_VOTE]

 2. ONLINE   ff3b9da031064fccbfab4b57933f12e1 (/dev/oracleasm/disks/OCR_VOTE_DISK_2) [OCR_VOTE]

 3. ONLINE   44e50015bcf24f7cbfc1b9348fdbe568 (/dev/oracleasm/disks/OCR_VOTE_DISK_3) [OCR_VOTE]

 4. ONLINE   de64da366c164f5cbfba2761df5948d5 (/dev/oracleasm/disks/OCR_VOTE_DISK_4) [OCR_VOTE]

 5. ONLINE   4485ff5940384f85bf524a81090c6bd8 (/dev/oracleasm/disks/OCR_VOTE_DISK_5) [OCR_VOTE]

Located 5 voting disk(s).

[root@srv2 ~]#

Note : Whether I create the DiskGroup with Normal or High Redundancy, it will still show only 1 OCR because there is only 1 Primary OCR location (Normal or High Redundancy will automatically create 1 or 2 Secondary OCR copy).

It is possible to add another location for OCR in this manner (where I add to the FRA DiskGroup):

[root@srv1 ~]# ocrconfig -add +FRA

[root@srv1 ~]# ocrcheck

Status of Oracle Cluster Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      84232

         Available space (kbytes) :     407452

         ID                       : 1183403784

         Device/File Name         :  +OCR_VOTE

                                    Device/File integrity check succeeded

         Device/File Name         :       +FRA

                                    Device/File integrity check succeeded

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

         Cluster registry integrity check succeeded

         Logical corruption check succeeded

[root@srv1 ~]#

[root@srv2 ~]# ocrcheck

Status of Oracle Cluster Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      84232

         Available space (kbytes) :     407452

         ID                       : 1183403784

         Device/File Name         :  +OCR_VOTE

                                    Device/File integrity check succeeded

         Device/File Name         :       +FRA

                                    Device/File integrity check succeeded

                                    Device/File not configured

                                    Device/File not configured

                                    Device/File not configured

         Cluster registry integrity check succeeded

         Logical corruption check succeeded

[root@srv2 ~]#

Furthermore, each node of the Cluster has a Local Cluster Registry (that is called an OLR) :

[root@srv1 ~]# ocrcheck -local

Status of Oracle Local Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      83144

         Available space (kbytes) :     408540

         ID                       : 1343496565

         Device/File Name         : /u01/app/grid_base/crsdata/srv1/olr/srv1_19.olr

                                    Device/File integrity check succeeded

         Local registry integrity check succeeded

         Logical corruption check succeeded

[root@srv1 ~]#

[root@srv2 ~]# ocrcheck -local

Status of Oracle Local Registry is as follows :

         Version                  :          4

         Total space (kbytes)     :     491684

         Used space (kbytes)      :      83132

         Available space (kbytes) :     408552

         ID                       : 1914984123

         Device/File Name         : /u01/app/grid_base/crsdata/srv2/olr/srv2_19.olr

                                    Device/File integrity check succeeded

         Local registry integrity check succeeded

         Logical corruption check succeeded

[root@srv2 ~]#

If you are worried about Failure Groups for the OCR_VOTE DiskGroup, you can see that the FailureGroups are automatically created for this High Redundancy DiskGroup :

SQL> l

  1  select g.name, d.disk_number, d.label, d.failgroup

  2  from v$asm_diskgroup g right join v$asm_disk d

  3  on g.group_number = d.group_number

  4  where g.name = 'OCR_VOTE'

  5* order by 1,2

SQL> /

NAME         DISK_NUMBER LABEL              FAILGROUP

------------ ----------- ------------------ ----------------

OCR_VOTE               0 OCR_VOTE_DISK_1    OCR_VOTE_0000

OCR_VOTE               1 OCR_VOTE_DISK_2    OCR_VOTE_0001

OCR_VOTE               2 OCR_VOTE_DISK_3    OCR_VOTE_0002

OCR_VOTE               3 OCR_VOTE_DISK_4    OCR_VOTE_0003

OCR_VOTE               4 OCR_VOTE_DISK_5    OCR_VOTE_0004

SQL>