How to monitor ASM Disk group usage on OEM Grid

1. Connect to OEM
2. Connect to the Host
3. From the Host –> Go to Target Tab
   
4. From the listed target, select ASM by looking at type as  “Automatic Storage Management”
   
   
   
5. Now select type ASM, then we will be landed at ASM on OEM Grid Control.
6. On the Home Page of ASM, we can find the Disk group usage
   
   
7. Also from the Home, go to tab Disk Group
   
   
   

Disk group has used % of safely usable free space

OEM Alert Message looks like;

Message=Disk group DISGKGROUP_FLASH_01 has used 75.08% of safely usable free space. Metric=Disk Group Used % of Safely Usable Metric value=75.08 Disk Group Name=DISGKGROUP_FLASH_01 Severity=Warning Target Name=+ASM1_DBSRVR.siva.com Target type=Automatic Storage Management Host=dbsrvr.siva.com Occurred At=Sep 29, 2011 11:14:52 PM IST Acknowledged=No Notification Rule Name=DBSrvr ASM Health Check Notification Rule Owner=DBA

 

By default:
This metric will generate a warning alert if the Disk Group is using 90% of the Safely usable space and
Critical warning for 100 %. Threshold limit can be changed to generate alert at different values.

This metric is collected at a time interval of 15 minutes.

Metric Collection:
This metric is collected from the view V$ASM_DISKGROUP_STAT

Used % of Safely Usable = 100 - (usable_file_mb/usable_total_mb)*100 Where usable_total_mb = total_mb - required_mirror_free_mb)/redundancy_factor

total_mb and required_mirror_free_mb will come from the V$ASM_DISKGROUP_STAT  view column and

Redundancy Factor	Disk Group Type
1	External
2	Normal
3	High

Query:

select 100-(FREE_MB/TOTAL_MB)*100 as "Used % Safely Usable Area",  Name from v$asm_diskgroup_stat

Alternatively connect to ASM and check the free space;

ASMCMD> lsdg

Workaround:
If the Archive Log file occupies the ASM Disk group, move the files or delete files to free up Disk group.

Permanent Resolution:
New disks can be added in a disk group to avoid the alerts.
Go to the Disk Group general page ---> and click on add button to add a new disk to a disk group.

find: missing conjunction

$  find . -type d –name siva*

Resolution:  Use single quote on the string in –name clause

Ex:   $  find . -type d –name ‘siva*’

How to find the open mode status of database?

Option 1:

select status from v$instance;

Option 2:

select open_mode from v$database;

Option 3:

Search Alert Log for string of “Database” or “alter database”.

How to generate AWR Report?

Method 1:  By Querying

1. Query dba_hist_snapshot to find the snap id for the interval you are looking for.

SELECT dbid, snap_id, begin_interval_time, end_interval_time from dba_hist_snapshot order by begin_interval_time;

2.

spool siv_awr_201109.lst SELECT output FROM TABLE (dbms_workload_repository.awr_report_text(3463084831, 1, 18048, 18050)); spool off

Method 2:

@?/rdbms/admin/awrrpt.sql

It is an interactive script that can be used to generate HTML or text reports. The script prompts for type of report
requested and prompts for number of days of snapshots to choose from so based on that it displays snap ids to
choose the start and end snapshot it.

@?/rdbms/admin/awrrpti.sql	Script can be used for the specified database and instance so the script in addition will prompt for dbid and instance number.
@?/rdbms/admin/awrddrpt.sql	Script can be used to generate a combine report of 2 different snapshots for comparison of performance in one report so it will prompt for two pairs of snapshot snapshots to compare against.
@?/rdbms/admin/awrinfo.sql	Script print AWR information like space usage by AWR, subset of AWR snap ids, Automatic Database Diagnostic Monitor (ADDM), Active Session History (ASH) information.

Sequence of steps performed when opening up a database

After issuing of SHUTDOWN ABORT command, when opening up database following step are performed

1. SPFile / PFile:             Server Parameter file ( SP File ) or the initialization parameter (initSID.ora / PFILE ) file is read
2. Memory :                      SGA is allocated
3. Background Process: Background process are started
4. Control File :                Control file is read
5. Redo Log File:              Redo Log file is read
6. Data File:                       Data files are checked for consistency
7. Instance Recovery:   Instance Recovery is started