Setting Path Policy on Only Single Datastore

[MihirP]

Hello,

I want to change Path Policy on ONLY ONE Datastore to Round Robin. This is currently set to Most Recently Used.

I found one vmware KB article 2000552 explaining to change this. But still not clear;

This 1 Datastore is connected to 5 hosts.

1) Do I need to login into each host (putty) and apply the command?

2) How to know which policy needs to be set to RR, as after loging into one host and executing below command, lists storage array type as attached in "Path Policy 2".

     # esxcli storage nmp satp list

3) Please let me know step by step commands.

4) Is Host reboot or any other such restart is required that may impact production hours?

5) Can this be simply done through vSphere Client?;

     Select RUNTIME NAME ==> drop down path selection, select RR ==> click CHANGE

Appreciate your help in advance.

Thanks,

Mihir

[admin]

check kb 1017760... http://www.vmwareinfo.com/2010/07/how-to-enable-alua-and-round-robin.html

[MihirP]

Is host reboot really required?

Also can you please review the attached screenshot of esxcli command and let me know the command to execute for changing to RR.

[rrz2012]

No reboot is required.

You have to make changes in all the hosts that you want the policy to be changed on.

• Round Robin (RR): Uses an automatic path selection rotating through all available paths, enabling the distribution of load across the configured paths.
  
  
  • For Active/Passive storage arrays, only the paths to the active controller will be used in the Round Robin policy.
  • For Active/Active storage arrays, all paths will be used in the Round Robin policy.
• 
  Note: This policy is not currently supported for Logical Units that are part of a Microsoft Cluster Service (MSCS) virtual machine.

Command will vary to your ESX/ESXi version, best is to refer the documentaion for exact command on changing the policy.

For example:

http://communities.vmware.com/thread/331346?start=0&tstart=0

[admin]

Yes reboot is not required. The only thing is to ensure there are no live IOs on the concerned datastore

[Cyberfed27]

I have not had to do a reboot. I've changed many of our datastores to RR from the default VMware (Fixed) policy. I have seen I/O go active on all paths without a reboot.

Also you dont need to do this via command line it can be done in vCenter.

Select your host - configuration tab - storage - right click the datastore and select properties, you can change it to RR in 'manage paths'.

Remember that this policy is host based, meaning if you change it to RR on say DATASTORE1 on HOST1 if you look at DATASTORE1 on HOST2 it will not have RR unless you set it there as well.

[Bharatk]

Hello All,

Anybody knows what will be impact on running VMs.

We have same scenario on HP storage currently the LUNs have MRU path selection policy set & now HP suggested to change it to Round Robin.

But we are in middle of that if we directly change it from datatstore level will that impact on running VMs or any performance degradation will happen.

We have thought to mirate all the running VMs on another datastore & make the changes on empty datastore.

Can anyone please answer my queries?