Thinking about how to deploy SES for block-oriented applications "in smart way", I made a conclusion the iSCSI gateways should be deployed at the same servers with OSD nodes.

Pro:
- The "locality" of the iSCSI gate and corresponding image container might increase the productivity by removing LAN infrastructure from "local" data path.
- If the cluster is not tweaked, the possibility of local data hit is 1 / OSD_Number. Thus, the smaller the cluster, the greater the gain.
- If the CRUSH map will be tweaked to store more container data locally to their iSCSI gates, the gain will be increased.
- The iSCSI multipathing might increase the performance as well.
- If the CPU will be saturated, the classic Hi-End approach "one role per node" still might be used.

Contra:
- The amount of administrative work is increased.
- Will SUSE still support such non-standard configuration? For example, 3 nodes for monitors and 10 nodes for OSD+iSCSI...

Am I right?