Understanding difference between 7-mode and c-dot from a systemshell point of view

There is a huge difference in the way the Ontap shell communicates with the layer beneath.. In a 7mode all the configuration files are stored in the the /etc directory... for example: /etc/rc, /ect/exportfs, /etc/hosts..

But when it comes to cluster mode.. we have the files present.. but they are actually not really used.. Instead all the files are managed by the RDB (replicating database).. 

A replication ring is a set of identical processes running on all nodes in the cluster.

The basis of clustering is the replicated database (RDB). An instance of the RDB is maintained on each node in a cluster. There are a number of processes that use the RDB to ensure consistent data across the cluster. These processes include the management application (mgmt), volume location database (vldb), virtual-interface manager (vifmgr), and SAN management daemon (bcomd).

For instance, the vldb replication ring for a given cluster consists of all instances of vldb running in the cluster.

RDB replication requires healthy cluster links among all nodes in the cluster. If the cluster network fails in whole or in part, file services can become unavailable. The cluster ring show displays the status of replication rings and can assist with troubleshooting efforts..

Lets jump into the systemshell... and from there to the bash shell and exactly see how it is working.

PLEASE DON'T TRY IT IN PRODUCTION, UNLESS YOU KNOW WHAT YOU ARE DOING.

cluster600::*> systemshell

  (system node systemshell)

Data ONTAP/amd64 (cluster600-01) (pts/2)

login: diag

Password:

Last login: Fri Feb 12 11:33:17 from localhost

Warning:  The system shell provides access to low-level

diagnostic tools that can cause irreparable damage to

the system if not used properly.  Use this environment

only when directed to do so by support personnel.

cluster600-01%

cluster600-01%

cluster600-01% sudo bash

bash-3.2#

bash-3.2#

bash-3.2# cd /mroot/etc/cluster_config/rdb

bash-3.2# ls

Bcom            Management      VLDB            VifMgr

bash-3.2#

These are the four files that contain are contained in the RDB.. Can we change it.. Yes we can, but needs lot of understanding as how it works to do it.. I have tried doing it and it works.. but its a long process. The better option is to use the cluster command line.. that's the actual process.. 

In senarios when the there is a disaster this is the way to go.. 

In the next blog, I'll walk through the way how the junction path works and whats the difference when it comes to 7mode and c-dot

PLEASE WRITE BACK IF THIS WAS USEFUL.