Troubleshooting › Setting the Number of Channels for Backup and Restore

Setting the Number of Channels for Backup and Restore

Symptom:

How can I set the number of channels for backup and restore jobs?

Solution:

When you are using the Agent for Oracle options, the maximum number of channels is 255. However, the maximum number of channels for an Oracle instance depends on the current Oracle running status, load status, hardware, and Oracle instance parameters. You can perform the following steps to set the number of channels.

To set the Number of Channels for Backup and Restore

1. Check the computer environment variable NUMBER_OF_PROCESSORS to get the processor count.
2. Log into SQL*Plus prompt.
3. Execute command to check whether the I/O slave is enabled.

   show parameter backup_tape_io_slaves
   

4. Execute command to check the maximum processes that can be used in the current Oracle instance.

   show parameter processes 
   

5. Execute command

   select count (*) from v$process
   

   Check the current processes count. You could calculate the maximum channel number you could use for backup and restore. Calculate the result of (<maxprocesses> - <current processes used>) / (processor count + 1).

   1. When the I/O slave is TRUE, if the result is less than 35, then the max channel number is that result, otherwise, the maximum channel number is 35.
   2. When the I/O slave is FALSE, if the result is less than 255. Then the maximum channel number is that result, otherwise, the max channel number is 255.