User manual

bACkground ACtivitieS SettingS
Background activities can be configured to use more or fewer system resources. Settings
should be balanced according to network demands. If the DataGuard Appliance will be
heavily used, for example, performance will be a higher priority. The rates for the various
background activities are:
• Low—Fewer system resources to the rebuild, more to data read/write operations.
• Medium—Balances system resources between the rebuild and data read/write
operations.
• High—More system resources to the rebuild, fewer to data read/write operations.
The following table shows available settings for background activities:
Activity
Setting Description
Rebuild Rate
This is controls the speed of rebuilding a new physical drive that
replaces a failed physical drive. The default is High.
Background
Synchronization
Rate
This controls the speed of background synchronization. The default is
Low.
Logical Drive
Initialization Rate
This controls the speed of logical drive initialization. The default is
Medium.
Redundancy Check
Rate
This controls the speed of logical drive initialization. The default is
Medium.
Note that redundancy checking can be done during off hours using the
Scheduler.
Migration Rate
This controls the speed of RAID level migration (i.e. changing the type
of RAID). The default is High. Note that RAID level migration is typically
very slow even at the highest rate, and has a large impact on device
performance.
PDM Rate
Predictive Data Migration is a process that is triggered if the Media
Patrol operation detects too many errors (as determined by the
Reassigned Block Threshold and Error Block Threshold). Use this to
control the rate of that migration. The default level is High.
Transition Rate
The Transition Rate controls speed at which a revertible disk that is part
of an array goes through the process of transition back to spare drive
status. The default rate is Medium.
Reassigned Block
Threshold
When an error occurs in a physical drive, the directions to the block
containing the error are reassigned. When the number of reassigned
blocks exceeds the threshold, PDM is triggered.
Error Block
Threshold
When an error occurs in the data or the physical media in a disk drive,
the block is marked and added to the block error count. When the
number of error blocks exceeds the threshold, PDM is triggered.
Enable Media Patrol
Media Patrol is enabled by default. Use this option to toggle enable/
disable for Media Patrol.
Enable Auto Rebuild
Auto Rebuild is the function that rebuilds a hard disk drive when you
swap out a failed drive with a new one.
Administration > Background Activity > Settings
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