Application-Based Recovery and Directed Mirror Reads

To optimize data recovery in Solaris Volume Manager for Sun Cluster, applications such as Oracle Real Application Clusters require the ability to manage and control the recovery of data. Enabling an application to control the recovery improves the performance of the recovery. The ioctls DKIOGETVOLCAP, DKIOSETVOLCAP, and DKIODMR provide support for an application's data management recovery in a cluster environment. These ioctls provide an application with the following capabilities:

• Application Based Recovery (ABR)—Allows the application to control the recovery of data on mirrored volumes

• Directed Mirror Reads—Allows the application to direct reads to specific submirrors and to determine the state of the data

For more information on the ioctls used with application-based data management recovery, see the dkio(7I) man page.

A RAID-1 volume with the resynchronization option set to application-based recovery only has a mirror owner during the application-based recovery process. The following output from the metastat -s diskset-name command shows a RAID-1 volume in a normal state. The resynchronization option is set to application-based recovery. There is no mirror owner.

# metastat -s red
red/d24: Mirror
    Submirror 0: red/d20
      State: Okay
    Submirror 1: red/d21
      State: Okay
    Pass: 1
    Read option: roundrobin (default)
    Write option: parallel (default)
    Resync option: application based
    Owner: None
    Size: 825930 blocks (403 MB)