CVM i/o and distributed locking

[slan]

I am trying to understand how the CVM does i/o for a cluster application like RAC. The following article suggests that all i/o from the CVM client is shipped to CVM server which does the real i/o to disk thereby there is no need for a Global lock manager. This seems a little unbelievable to me from performance standpoint, could someone confirm this.

 http://www.remote-dba.cc/teas_aegis_rac24.htm

If it is really true, it means that user data goes over the private link and so the network traffic should be quite high. ( similar to NFS server). Of course this method takes care of cluster write ordering issues as well simplify replication of data.

thanks a lot in advance..

[M__Braun]

The article is talking about VM configuration and metadata changes. The actual I/O is always done by the local node:

http://www.symantec.com/business/products/overview.jsp?pcid=2245&pvid=145_1
http://eval.symantec.com/mktginfo/products/Datasheets/High_Availability/storage_foundation_oracle_rac_datasheet.pdf

http://www.symantec.com/business/products/overview.jsp?pcid=2245&pvid=209_1
http://eval.symantec.com/mktginfo/products/Datasheets/Storage_Server_Management/storage_foundation_cfs_datasheet.pdf


The existing architecture was enhanced with the Multiple Transaction Server concept (see provided links) in the 5.0 version. This eleminates unnecessary metadata communication throughout the cluster.

I hope this helps.

Regards

Manuel