1. Scaleout User's Guide
  2. Recovering from Failure
  3. Displaying the Database, Replica Set and Element Status

Displaying the Database, Replica Set and Element Status

You can display the database, replica set and element status.

The element status shows:

  • If the element is loaded (opened).

  • If the element is in process of a change, such as being opened (opening), loaded (creating, loading), unloaded (unloading), destroyed (destroying) or closed (closing).

  • If the element or its data instance has failed and is waiting on the seed element to recover, then the status displayed is waiting for seed. The element that failed with the latest changes, known as the seed element, is recovered first to the latest transaction in the checkpoint and transaction log files. All other elements in the replica set are copied from the seed element of the replica set.

  • If the element is not up (evicted or down).

The following section describe examples of how to display the status of the database, data space groups, replica sets and elements. See Troubleshooting Based on Element Status.

Display the Status of the Database and All Elements

You can use the ttGridAdmin dbStatus -all command to list the current status for the database, all elements, replica sets and data space groups in your database.

The first section describes the status of the overall database. In this example, the database has been created, loaded, and open. The status also shows the total number of created, loaded and open elements.

The database status shows the progression of the database being first created, then loaded and finally opened. In bringing down the database, the reverse order is performed, where the database is first closed, then unloaded and finally destroyed.

% ttGridAdmin dbStatus database1 -all 
Database database1 summary status as of Thu Feb 22 07:37:28 PST 2018
 
created,loaded-complete,open
Completely created elements: 6 (of 6)
Completely loaded elements: 6 (of 6) 
Completely created replica sets: 3 (of 3) 
Completely loaded replica sets: 3 (of 3)  
 
Open elements: 6 (of 6)

However, if the database status shows that the database is created, loaded and closed, then the database has not yet been opened. The following example shows that the database is not open yet, but that the distribution map has been updated, showing the created and loaded replica sets. Note that none of the elements are opened until the database is opened.

% ttGridAdmin dbStatus database1 -all
Database database1 summary status as of Thu Feb 22 07:37:01 PST 2018
 
created,loaded-complete,closed
Completely created elements: 6 (of 6)
Completely loaded elements: 6 (of 6) 
Completely created replica sets: 3 (of 3) 
Completely loaded replica sets: 3 (of 3)  
 
Open elements: 0 (of 6)

The second section provides information about the elements: the host and instance name in which each element exists, the number assigned to the element, and the status of the element. 

Database database1 element level status as of Thu Feb 22 07:37:28 PST 2018
 
Host  Instance  Elem Status Date/Time of Event  Message
----- --------- ---- ------ ------------------- -------
host3 instance1    1 opened 2018-02-22 07:37:25
host4 instance1    2 opened 2018-02-22 07:37:25
host5 instance1    3 opened 2018-02-22 07:37:25
host6 instance1    4 opened 2018-02-22 07:37:25
host7 instance1    5 opened 2018-02-22 07:37:25
host8 instance1    6 opened 2018-02-22 07:37:25

The third section provides information about the replica sets. In this example, there are three replica sets. In addition to information about the elements, it also provides the number of the replica set in which each element exists, identified by the RS column. The data space group in which each element exists (within its data instance within its host) is identified with the DS column. Notice that each replica set has one element in each data space group. 

Database database1 Replica Set status as of Thu Feb 22 07:37:28 PST 2018
 
RS DS Elem Host  Instance  Status Date/Time of Event  Message
-- -- ---- ----- --------- ------ ------------------- -------
 1  1    1 host3 instance1 opened 2018-02-22 07:37:25
    2    2 host4 instance1 opened 2018-02-22 07:37:25
 2  1    3 host5 instance1 opened 2018-02-22 07:37:25
    2    4 host6 instance1 opened 2018-02-22 07:37:25
 3  1    5 host7 instance1 opened 2018-02-22 07:37:25
    2    6 host8 instance1 opened 2018-02-22 07:37:25

The final section organizes the information about the elements to show which elements are located in each data space group, shown under the DS column. In this example, there are two data space groups. The elements are organized either under data space group 1 or 2. 

Database database1 Data Space Group status as of Thu Feb 22 07:37:28 PST 2018
 
DS RS Elem Host  Instance  Status Date/Time of Event  Message
-- -- ---- ----- --------- ------ ------------------- -------
 1  1    1 host3 instance1 opened 2018-02-22 07:37:25
    2    3 host5 instance1 opened 2018-02-22 07:37:25
    3    5 host7 instance1 opened 2018-02-22 07:37:25
 2  1    2 host4 instance1 opened 2018-02-22 07:37:25
    2    4 host6 instance1 opened 2018-02-22 07:37:25
    3    6 host8 instance1 opened 2018-02-22 07:37:25

The following shows the status if you evicted one of your replica sets without replacement. While the database is loaded and opened, it shows that there are six created elements, but only four of those are loaded. There is one less replica set in all displayed sections and the evicted elements are shown as evicted with their status.

% ttGridAdmin dbStatus database1 -all
Database database1 summary status as of Thu Feb 22 07:52:08 PST 2018
 
created,loaded-complete,open
Completely created elements: 6 (of 6)
Completely loaded elements: 4 (of 6)
Completely created replica sets: 2 (of 2)
Completely loaded replica sets: 2 (of 2)
 
Open elements: 4 (of 6)
 
Database database1 element level status as of Thu Feb 22 07:52:08 PST 2018
 
Host  Instance  Elem Status  Date/Time of Event  Message
----- --------- ---- ------- ------------------- -------
host3 instance1    1 evicted 2018-02-22 07:52:06
host4 instance1    2 evicted 2018-02-22 07:52:06
host5 instance1    3 opened  2018-02-22 07:37:25
host6 instance1    4 opened  2018-02-22 07:37:25
host7 instance1    5 opened  2018-02-22 07:37:25
host8 instance1    6 opened  2018-02-22 07:37:25
 
Database database1 Replica Set status as of Thu Feb 22 07:52:08 PST 2018
 
RS DS Elem Host  Instance  Status Date/Time of Event  Message
-- -- ---- ----- --------- ------ ------------------- -------
 1  1    3 host5 instance1 opened 2018-02-22 07:37:25
    2    4 host6 instance1 opened 2018-02-22 07:37:25
 2  1    5 host7 instance1 opened 2018-02-22 07:37:25
    2    6 host8 instance1 opened 2018-02-22 07:37:25
 
Database database1 Data Space Group status as of Thu Feb 22 07:52:08 PST 2018
 
DS RS Elem Host  Instance  Status Date/Time of Event  Message
-- -- ---- ----- --------- ------ ------------------- -------
 1  1    3 host5 instance1 opened 2018-02-22 07:37:25
    2    5 host7 instance1 opened 2018-02-22 07:37:25
 2  1    4 host6 instance1 opened 2018-02-22 07:37:25
    2    6 host8 instance1 opened 2018-02-22 07:37:25

See Troubleshooting Based on Element Status in this guide and Database Management Operations and Monitor the Status of a Database (dbStatus) in Oracle TimesTen In-Memory Database Reference.