In Exadata, database communicate with storage server using libcell utility and transfer data from storage tier to database server using ROCE (RDMA over converged ethernet) protocol if require. Since multiple storage servers are available in Exadata and database nodes communicate with them, so how the database comes to know that which storage server is running on which storage network interface and to validate this database server uses 2 storage server files that resides in database server.
(2) Cellinit.ora
NOTE: Both the files are important for DB node to get the cell node IP information.
Cellinit.ora: Cellinit.ora
are host specific and contain all the database IP Address that connect to the
storage network used by Exadata storage server. This file must exist in each
and every node of Exadata RACK. All the IP address are specified in a classless
inter-domain routing (CIDR) format.
Location Of Cellinit.ora: /etc/oracle/cell/network-config/cellinit.ora
[oracle@exatest ~]# cat /etc/oracle/cell/network-config/cellinit.ora
ipaddress2=192.168.14.11/23
ipaddress1=192.168.14.10/23
What Is Classless Inter-Domain Routing (CIDR) Format
We can represent the subnet mask
in 2 ways either in traditional way where we define the complete network
address followed by subnet mask and the other one is in CIDR format which
basically shorten the subnet mask into its total number of active bits where
each block is represented by 8 bit per digit or the collective size is 4 bytes.
E.g: 192.168.10.0/24,
Here /24 is a shortened representation of subnet mask 255.255.255.0 in CIDR
format
Cellip.ora: It contains IP Addresses of all the cell storage server that are accessible to the database server.
Location Of Cellip.ora: /etc/oracle/cell/network-config/cellip.ora
[oracle@exatest ~]# cat /etc/oracle/cell/network-config/cellip.ora
cell=”192.168.14.22;192.168.14.23”
cell=”192.168.14.24;192.168.14.25”
cell=”192.168.14.26;192.168.14.27”
NOTE: In
Quarter RACK, 6 IPs entries exist in cellip.ora and the no. of IPs increases on
the basis of Exadata cluster configuration such as Half OR Full RACK.
What To Check If Connectivity Issue Occur Between Storage Server and Database Node
If the connectivity issue occurred in between database and storage server then we can check the ocssd.log where it reports the connectivity issue between storage server and database node.
