scogeb
13 years agoLevel 3
DMP DSM for VCS SQL, Round Robin vs. Dynamic Least Queue Depth
What is the recommended setting for the Load Balance Policy for a SQL environment? Or, where can I find more information about the available settings? Thanks!
Explanation of DMP setting should be the same, regardless of product, so here is the description from SFW 6.0 from SFW admin guide:
Dynamic Least Queue DepthSelects the path with the least number of I/O requests in its queue for thenext data transfer.For example, if you have two active paths, path A with one I/O request andpath B with none, DMP DSMs would select the path with the least numberof I/O requests in its queue, path B, for the next data transfer.Round Robin with SubsetUses a subset of paths, each in turn, in round-robin fashion. The userspecifies the paths for data transfer that make up the subset. The remainingpaths are in standby mode.For example, if you have three active paths, path A, path B, and path C andyou specify the subset to contain path A and path B, then DMP DSMs woulduse path A for one data transfer and then use path B for the next. Path Cis in standby mode and is used if path A or path B fails.You may just have "Round Robin" option, rather than "Round Robin with Subset", so this will just mean DMP will use all available paths, rather than been able to choose a subset. In SFW 6.0 there are lots of other modes as well, but this may not be available in the version you are using.I woud guess that if you have some switches that are higher in performance or some switches are heavily loaded (so might be slower), then "Dynamic Least Queue Depth" should work better, but if all paths go through switches that are the same and equally loaded it probably makes no difference.Mike