What is rebalancing in asm

You might want to do a manual rebalance operation to control the speed of what would otherwise be an automatic rebalance operation. It can be set to a minimum value of 0 which halts a rebalancing operation until the statement is either implicitly or explicitly rerun. A higher value increases the speed of the rebalance operation. The power level of an ongoing rebalance operation can be changed by entering the rebalance statement with a new level. REBALANCE command by default returns immediately so that you can run other commands while the rebalance operation takes place asynchronously in the background.

The wait functionality is especially useful in scripts. The command also accepts a NOWAIT keyword, which invokes the default behavior of conducting the rebalance operation asynchronously. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email.

This site uses Akismet to reduce spam. Learn how your comment data is processed. Email Address:. Takip Et. Website Built with WordPress. Assume that there are data centers which are located 40 miles distant from each other and the goal is to mirror the two sites.

For this, use ASM shared storage for an Oracle cluster which has member nodes with active instances in each site that is to be mirrored.

In 10g, an instance in an Oracle Real Application Cluster must always use the primary copy of an extent in order to read it, even if the secondary copy is located in the local fail group and the primary copy is on the remote site. This has the negative effect that the primary copy of an extent needs to be read from the remote disks into the other instance and would be shipped through the interconnect to the requesting instance.

This problem is addressed in 11g with the preferred mirror read feature. It is possible now to define preferred read fail groups within an ASM disk group for each instance in a clustered ASM configuration, which allows for a preferred read of the local to the instance copy of an extent no matter if it is the primary or the secondary copy.

This configuration is shown in the below graphic. Figure 6: Stretched Oracle 10g Cluster with Two ASM Fail Groups The above graphic shows the situation in a 10g extended cluster configuration with two mirrored sites which both use the same ASM diskgroup with normal redundancy and two fail groups. Each fail group holds either the primary or the secondary copy of every ASM extent. Now look at how to setup preferred mirror read. Assume that there are two sites which need to be mirrored with ASM using normal redundancy with two failure groups and preferred mirror read.