Oracle Switch Intervals

Purpose

This monitor will check the time interval between log switches and notify if it happens too often.

Differences between Archive and Redo logs

<lu> <li>Archive logs are archived redo(online) log files.</li> <li>In redo log files are all changes that happened to your data.</li> <li>If your database is in archivelog mode, than redo logs can't be overwritten, they are archived in some other location when they are full.</li> <li>Redo and archive logs are used in various database recovery scenarios</li> </lu>

Recommended redo log switch frequency per hour

<lu> <li>In a production environment it is important to size your online redo log files to ensure that the frequency of redo log switches is not more than 5 log switches per hour during peak DML activity.</li> <li>A log switch is the point at which the database stops writing to one redo log file and begins writing to another. ...</li> <li>You can also force logs witches manually.</li> <li>Oracle Database assigns each redo log file a new log sequence number every time a log switch occurs and LGWR begins writing to it.</li> </lu>

Oracle recommendation

Oracle's recommendation is that the interval for log switches be 15 to 30 minutes apart, with a maximum of four log switches per hour

Configuration hints

Create a new rule and set the thresholds accordingly. You must use multi-threshold syntax with this monitor.

Atomic fields

Period (hours)	The period of time in the past to look for switch interval. Make sure the period overlaps with the monitor schedule so you won't miss any dump

Surveillance table

Parameter	Description
Active	To enable/disable a rule.
Max switches per hour	The threshold for the maximum number of switches per hour.
Max interval with no switches	The threshold for the maximum number of time without switches.
Average switches per hour	A threshold for the maximum average time interval between switches per hour.
Auto clear	If checked, the alarm will be cleared as soon as the alarm condition is not met anymore.
Alarm tag	This field allows to add custom text within the alarm message. %MSG% variable will containthe actual generated message and can be used such as: “my_prefix %MSG% my_suffix”. By default, tagwill be used as prefix.
Alarm	To enable alarm sending
Metric	To enable metric sending
Report	If checked, this line of surveillance will used for showing threshold and severity in the daily report

Generated metrics

metricId	metricUnit	metricTarget	metricDescription
ORACLE_DATABASE_SWTINTV_MAX_SWT_PER_HOUR
ORACLE_DATABASE_SWTINTV_MAX_INTV_WO_SWT
ORACLE_DATABASE_SWTINTV_AVG_SWT_PER_HOUR