SCAN ISSUES - RAC

TOP 5 ISSUES WITH SCAN VIP AND LISTENER

               

ISSUE 1 :

SCAN VIP showing status UNKNOWN – CHECK TIMED OUT

·         crsctl stat res –t

                 ora.scan1.vip 1 ONLINE UNKNOWN rac2 CHECK TIMED OUT

                 ora.scan2.vip 1 ONLINE ONLINE rac1

                 ora.scan3.vip 1 ONLINE ONLINE rac1

CAUSE : 

/ec/resolv.conf is not consistent across all nodes .

SOLUTION :

·         Have /etc/resolv.conf consistent across all nodes

·         Reduce the value for lookup timeout so that the total lookup time is less than the check timeout for VIP resource. E.g.  add to /etc/resolv.conf : options timeout :1 

ISSUE 2 :

What to check on SCAN VIP’s before installing GRID and what to check after installation .

BEFORE INSTALLATION

          

            ·         /etc/resolv.conf must be consistent across all nodes 

            ·         SCAN should have the netmask already used by public interface  

            ·         “nslookup scan-name” should return name server and 3 ip addresses 

            ·         If tcp.validnode_checking=yes in GRID’s home sqlnet.ora, then TCP.INVITED_NODES will require the SCAN VIP’s and node                       VIP’s to be added to the Grid Infrastructure sqlnet.ora file.

AFTER INSTALLATION

      ·         crsctl status resource –w ‘TYPE=ora.scan_vip.type’    ---  it should show LISTENER_SCAN<X> ONLINE

Also use,

      ·         srvctl config scan

      ·         srvctl config scan_listener

      ·         cluvfy comp scan

ISSUE 3 :

Service not registered with SCAN listener after SCAN listener failover .

DESCRIPTION :

After SCAN VIP and SCAN listener failover, instance does not register with SCAN listener. It might happen for only 1 SCAN listener.

Client connection gets intermittent ORA-12514 TNS:listener does not currently know of service requested in connect descriptor.

SOLUTION :

For both above bugs , the work around is to unregister and register remote listener on the db instance which does not register to a SCAN listener , with the following steps :

show parameter remote_listener ;
alter system set remote_listener=’   ‘ ;
alter system register ;
alter system set remote_listener=’<scan>:<port>’ ;
alter system register ;




ISSUE 4 :

SCAN VIP’s do not failover when public n/w is down .

DESCRIPTION :

SCAN VIP’s should failover to next node when public n/w is down. On 11.2.0.1 under some circumstances it is possible that SCAN VIP stays on wrong node.

SOLUTION :

Install last 11.2.0.1 PSU or 11.2.0.2/11.2.0.3  .




ISSUE 5 :

SCAN listener troubles .

CAUSE :

Listener.ora exists in /etc or /var/opt/oracle .
Default port 1521 not used .

SOLUTION:

Move listener.ora to other location. It is fixed in 11.2.0.3 and last 11.2.0.2 PSU .
SCAN listener port changed to default 1521 after upgrade to 11.2.0.3 GI from lower release .