SD secondary server

A shared-disk (SD) secondary server participates in high-availability cluster configurations. In such configurations, the primary server and the SD secondary server share the same disk or disk array.

An SD secondary server does not maintain a copy of the physical database on its own disk space. Rather, it shares disks with the primary server.

SD secondary servers must be configured to access shared disk devices that allow concurrent access. Do not configure an SD secondary server that uses operating system buffering, such as NFS cross-mounted file systems. If the SD secondary server instance and the primary server instance both are located on a single machine, then both servers can access local disks. If the SD secondary server and the primary server are on separate physical machines, then they must be configured to access shared disk devices that appear locally attached, such as Veritas or GPFS™.

SD secondary servers can be used in conjunction with HDR secondary servers, with RS secondary servers, and with Enterprise Replication.

SD secondary servers can be added to a high availability environment very quickly, because they do not require a separate copy of the disk. Because the SD server shares the disk storage resources of the primary server, it is recommended that you provide some other means of disk backup, such as disk mirroring, or the use of an RS secondary server or an HDR secondary server.

The following restrictions affect the promotion of database server instances that are shared-disk secondary servers:
  • An SD secondary server cannot be promoted to an RS secondary server.
  • An SD secondary server cannot be promoted to a standard server that would exist outside the primary high availability environment.

Copyright© 2019 HCL Technologies Limited