Tag Archives: Deep inside

Sad story about Oracle RDS and Infiniband relationship.

Hello everyone. Today I wanna tell you story how I’ve tried fit the RDMA with the help ISCSI iSER, and Oracle RDS into Infiniband environment. Looking ahead I’ll say. Oracle is not supporting RDS protocol outside of Oracle Engineered systems aka Exadata. This is the official position of Oracle which confirmed by the supporting team, but this information doesn’t exists in the documentation which is so rediculous. The support engineer is told me that, “there are so many systems which we are not supporting, so we don’t  consider is necessary to put this information into the documentation”. This is nice, isn’t it?

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Chicken-and-egg problem

You might wonder how CSSD, which is required to start the clustered ASM instance, can be started if voting disks are stored in ASM? This sound like a chicken-and-egg problem. Without access to the voting disks there is no CSS, hence the node can’t join the cluster. But without begin part of the cluster, CSSD can’t start the ASM instance. To solve this problem the ASM disk headers have metadata since 11.2. You can use kfed to read the headers of ASM disks containing a voting disk. The kfdhdb.vfstart and kfdhdb.vfend fields tell CSS where to find the voting file. This does not require the ASM instance to be up. Once the voting disks are located, CSS can access them and joins the cluster.