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Description of problem: Any chance of back porting the dm-service-time and dm-queue-length path selectors from dm-multipath that were included in 2.6.34 into the RHEL6 kernel for RHEL 6.4+? These new algorythims pretty much bring dm-multipath into 100% capable of any alleged feature benefits over commercial products such as EMC PowerPath. Having more than just simple round-robin is pretty much the only features missing from dm-multipath in comparison to those commercial products, so we are anxious to get these features in our RHEL systems native capabilites.
RHEL6 has always had these new path selectors. Closing NOTABUG.
FYI, the path-selector that is used can be configured in /etc/multipath.conf Either in the 'defaults' section (applies to all mpath devices), e.g.: defaults { ... selector "queue-length 0" } or in the per mpath 'device' section, e.g.: devices { device { ... path_selector "service-time 0" } } Not specifying a selector defaults to "round-robin 0" Other RHEL6 multipath info is available here: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/DM_Multipath/MPIO_Overview.html http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/DM_Multipath/config_file_devices.html
Thanks so much for the detailed answer. It is much appreciated.