Unity VM NMP setting

Question

Hi there … Please advise if anybody know the best practice for ESXi server with Unity Multipath configuration (VM NMP) I found below in Unity Doc…. Unity seems to have own Loadbalancing techniques if client has some multipath software installed. But not to sure what is the best setting to get Active/Active ( IO balancing ) result .  I found VNXe3200 best practice and its says vm setting should be roundrobbin , would Unity be the same ? Also in VNXe setting says , `` ESX NMP IOPs setting of 1 instead of the default of 1000``  what is the expected result reducing this number from 1000? From https://support.emc.com/docu71319_Unity:-High-Availability---A-Detailed-Review.pdf?language=en_US Page 14~ Unity leverages Asymmetric Logic Unit Access (ALUA) for host access. This enables multiple paths to be active for I/O, but some paths are optimized while others are non-optimized. The paths that are designated as optimized are the ones connected to the SP that owns that particular resource. If I/O is sent down the non-optimized path, the peer SP leverages the internal CMI (Common Messaging Interface) bus to redirect the I/O to the SP that owns the resource. This operation is completely transparent to the host and removes the need to trespass the resource to complete the I/O. However, if a large number of I/Os are received down the non-optimized path, the Unity system trespasses the LUN to the peer SP in order to optimize the data path. Figure 12 shows an asymmetric active/active configuration. Multi-pathing software, such as PowerPath, must be installed on the host in order to leverage ALUA. Multi-pathing software should be configured to use the optimized paths first and only use the non-optimized paths if there are no optimized paths available. If possible, use two separate Network Interface Cards (NICs) or Fibre Channel Host Bus Adapters (HBAs) on the host. This avoids a single point of failure on the card and also the slot on the server. >>>This means if Using VMware NMP , what will be the best practice ? nmp setting should be round robbin to get Active/Active result ? From VNXe3200 , https://support.emc.com/docu55593_VNXe3200-Best-Practices-For-Performance---Applied-Best-Practices-Guide.pdf?language=en_US Page 25 Configure ESX to use 'round robin' path settings Configure ESX NMP IOPs setting of 1 instead of the default of 1000 >>> Unity should be the same ? Also What is the expected affect to set 1 instead of default value of 1000 ? What this setting means in terms of IO ? thanks ! Aya

kelleg · Answer

The host should be set to Round Robin when connecting any the Unity array - same as the VNXe3200 - it uses the same functions.

The IOPs setting is actually called the "IO Operations Limit" - the default setting is 1000. What this means is that when Round Robin is the NMP that 1000 IO's are send down one optimized path than 1000 IO's down the second path, alternating between the two paths.

This assumes that you are using two HBA's (or iSCSI NIC) and four paths to the array. Each HBA is connected to two ports on the array - one to SPA and one to SPB. The LUN will be owned by either SPA or SPB. If the LUN is owned by SPA, then the IO will be sent to the LUN first down the HBA1 path then down the HBA2 path in a round robin method.

Host Unity

HBA1 <--> SPA port 0

HBA2 <--> SPA port 1

HBA1 <--> SPB port 0

HBA2 <--> SPB port 1

glen

ayas · Answer

HI Glen !

Thanks you so much for your great update ! Got it ,,,, will follow the VNXe3200 setting for now .. It would be great to get Unity Document to be created ,,, is there any plan for it ?

thanks!

Unity

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