This section discusses the following topics:
Except for disk requirements (which are shared with the primary server), hardware and software requirements are the same as for HDR secondary servers.
SDS nodes are not able to share temp spaces along with the primary. As a result, you have to specify temp space for each SDS node (there can be multiple DBSpace/chunks defined). The temp spaces are created when the SDS secondary is started. The dynamically created DBSpace/chunks are local to the SDS node. The DBSpace/chunks use the highest number to prevent any conflicts with chunk additions on the primary server. The primary and other SDS nodes are unaware of the local temp DBSpace.
Please review the next section on Onconfig parameters, and set each value before starting and SDS node.
Table 18. New onconfig parameters for SDS
|SDS_ENABLE||Set to 1 to enable SDS; 0 to disable|
|SDS_TIMEOUT||Specify an integer value for the amount of seconds a primary will wait for acknowledged log positions from the secondary nodes until it attempts to remove an SDS node|
|SDS_TEMPDBS||Uses the following pattern <name>,<path>,<pagesize>, <offset>,<size>. Since the SDS nodes are not able to share temp spaces, you have to specify for each secondary SDS node its own temp dbspace. The space will be created when the SDS secondary is started.|
|SDS_PAGING||Specify two files where the SDS node will maintain its flushed pages|
Compaired to starting HDR, ER, or RSS, the process of starting an Shared Disk Secondary is simple.
Table 19. Starting an SDS node for the 1st time
|Step||On the primary||On the SDS node|
|1||Set up shared disk environment|
|2||Set SDS_ENABLE to 1 on primary|
|3||Run onmode -d set SDS primary <alias>|
|4||Configure SDS_ENABLE, SDS_PAGING, and SDS_TEMPDBS|
|5||On SDS node, map the following to match the primary: ROOTNAME, ROOTPATH, ROOTOFFSET, ROOTSIZE, PHYSDBS, PHYSFILE, LOGFILES, LOGSIZE. It is advisable to map the other configuration parameters to match those of the primary server with the exception of DBSERVERALIASES, DBSERVERNAME, and SERVERNUM.|
|6||Start the SDS node with the command oninit|