DMP DSM for VCS SQL, Round Robin vs. Dynamic Least Queue Depth

Created: 15 Oct 2012 | Updated: 16 Oct 2012 | 2 comments

scogeb

This issue has been solved. See solution.

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!

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Storage and Clustering, Dynamic Multi-Pathing and Dynamic Multi-Pathing for VMware, Best Practice, Configuring, SQL, Windows, Performance, Tip/How to

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mikebounds Trusted Advisor Accredited

DMP DSM for VCS SQL, Round Robin vs. Dynamic Least Queue Depth - Comment:16 Oct 2012 : Link

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 Depth

Selects the path with the least number of I/O requests in its queue for the

next data transfer.

For example, if you have two active paths, path A with one I/O request and

path B with none, DMP DSMs would select the path with the least number

of I/O requests in its queue, path B, for the next data transfer.

Round Robin with Subset

Uses a subset of paths, each in turn, in round-robin fashion. The user

specifies the paths for data transfer that make up the subset. The remaining

paths are in standby mode.

For example, if you have three active paths, path A, path B, and path C and

you specify the subset to contain path A and path B, then DMP DSMs would

use path A for one data transfer and then use path B for the next. Path C

is 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

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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scogeb

DMP DSM for VCS SQL, Round Robin vs. Dynamic Least Queue Depth - Comment:16 Oct 2012 : Link

Thank you Mike. I found the information in the Admin guide per your suggestion.

DMP DSM for VCS SQL, Round Robin vs. Dynamic Least Queue Depth

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