coldaddy
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Contributor

NFS Storage Path Redundancy

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I want to configure my host's connectivity to NFS datastores to be load balanced and redundant. The configuration I propose is to use a vSwitch with 2 uplink nics (vmnic0 and vmnic1) both connected to the NFS VLAN. Then set up 2 VMKernel connections within the vSwitch, both configured on the NFS VLAN (different IP addresses but the same subnet). Finally, set up VMKernel1 with vmnic0 as Active and vmnic 1 as Standby. VMKernel2 is set up in an opposite way (vmnic1 is Active and vmnic0 is Standby. My question...will VMs that have datastores on NFS alternate between the 2 VMKernel connections as they power up? What will govern which VMKernel connection a particular VM uses? Is there a better way to achieve my goals (load balancing and redundancy to NFS storage)?

Thanks,

Steve

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ac57846
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Hot Shot

Steve,

Your two VMK ports show in the diagram as being on the same subnet so the VMK will only ever use one of them.

If the VMK ports were on different subnets and the storage systems were local on those two subnets then the VMK would use both, each VMK port for the NFS server on the same subnet.

i.e. VMK0 192.168.50.2/28 > NFS0 192.168.50.3 on pNIC0 active pNIC1 standby and VMK1 192.168.50.66/28 > NFS0 192.168.50.67 on pNIC0 standby pNIC1 active

This would distribute the load to two differnet NFS datastores on two different NFS servers across two pNICs. The VMK will only ever use a single pNIC at a time for each NFS server.

Having the two filers present the same data would not help as the VMK identifies NFS datastores by the server name and share name that is used. The two filers would have different server names so the VMK would see the shares on them as seperate datastores, even if they contained the same replicated data.

Keep in mind that multipathng for ESX is aimed at fault toerance, not load balancing.

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ac57846
Hot Shot
Hot Shot

Steve,

If you have a single VMKernel port connected to a vSwitch which has two physical NICs assigned then you have fault toerance at the physical layer, provided you allow the VMKernel port to use both NICs.

Remember that the two VMKernel IP addresses have a single TCP stack above them in the VMKernel. If they are on the same subnet then the VMKernel will only ever use one of them to reach the NFS server.

There is no way to load balance a connection from the VMKernel to a single IP address over multiple physical NICs, if you need more bandwidth you need higher bandwidth NICs, 10GBe or Infiniband.

coldaddy
Contributor
Contributor

If our NFS storage was on two separate subnets and the two VMKernel connections each conncted to one storage network would this allow for NFS load balancing (both still a part of a single vSwitch with 2 uplink nics VLAN tagged to both storage networks)?

Thanks for your help on this.

Steve

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coldaddy
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I am hoping someone will validate a design of balancing NFS load on an ESX host by having 2 VMKernel connections going to different NFS servers. I am trying to achieve end-to-end redundancy and load -balancing. Please have a look at a Visio I am attaching which illustrates this concept. Note the NetApp filers in the diagram are clustered.

Thanks,

Steve

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ac57846
Hot Shot
Hot Shot

Steve,

Your two VMK ports show in the diagram as being on the same subnet so the VMK will only ever use one of them.

If the VMK ports were on different subnets and the storage systems were local on those two subnets then the VMK would use both, each VMK port for the NFS server on the same subnet.

i.e. VMK0 192.168.50.2/28 > NFS0 192.168.50.3 on pNIC0 active pNIC1 standby and VMK1 192.168.50.66/28 > NFS0 192.168.50.67 on pNIC0 standby pNIC1 active

This would distribute the load to two differnet NFS datastores on two different NFS servers across two pNICs. The VMK will only ever use a single pNIC at a time for each NFS server.

Having the two filers present the same data would not help as the VMK identifies NFS datastores by the server name and share name that is used. The two filers would have different server names so the VMK would see the shares on them as seperate datastores, even if they contained the same replicated data.

Keep in mind that multipathng for ESX is aimed at fault toerance, not load balancing.

View solution in original post

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coldaddy
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The VMK pots in the diagram were supposed to be on different subnets... may have botched the diagram in this regard. I understand this distributes the load which is functionally the same as balancing the load, though it is not dynamic. Note the 2 filers are individual in the sense that they are separate NFS servers, but they have the ability to fail over if one filer fails (assume network persona and management of storage on failed filer).

I appreciate your help. I am marking this as answered. Don't spend all your points in one place <g>.

Thanks again,

Steve

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