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GreyhoundHH
Enthusiast
Enthusiast

Fault Tolerance LOgging Best practice

Hi,

we plan on integrating VMware Fault Tolerance in our environment.

Our hosts are each equipped with 2x 10G uplinks. So far we run everything over these uplinks (NFS, management, vMotion, VM Traffic).

Can we have FT Logging enabled on top of that?

Or should we plan another pair of 10G uplinks exclusively for FT Logging?

Any input on that appreciated.

Regards

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TheBobkin
Champion
Champion

Hello,

I would consider a single 10Gb link to be adequate for FT logging traffic in most cases, but the throughput depends on how busy a VM (and how many), a second link for redundancy might be prudent, over another switch if possible.

Not often to recommend a TT article but this one is good and has a formula for estimating the networking requirements and summarizes the FT section of the vSphere Availability guide quite well:

http://searchitchannel.techtarget.com/feature/VSphere-Fault-Tolerance-requirements-and-FT-logging

VMware FT logging bandwidth = (Avg disk reads (MB/s) ×

8 + Avg network input (Mbps)) × 1.2 [20% headroom ]

The vSphere Availability guide has more detailed info that informs us that yes, you should put FT logging on it's own Multi-gigabit link:

"Prerequisites

Multiple gigabit Network Interface Cards (NICs) are required. For each host supporting Fault Tolerance, a

minimum of two physical NICs is recommended. For example, you need one dedicated to Fault Tolerance

logging and one dedicated to vMotion. Use three or more NICs to ensure availability.

NOTE The vMotion and FT logging NICs must be on different subnets.":

pubs.vmware.com/vsphere-60/topic/com.vmware.ICbase/PDF/vsphere-esxi-vcenter-server-60-availability-g...

Bob

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GreyhoundHH
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Enthusiast

Thanks for the input.

Unfortunately the mentioned article is from 2011 and with vSphere 6 things in FT have change.

Especially regarding limitations and as far as I have understood the secondary VM is now using it's own VMDKs.

Does anyone know if a FT-protected VM has to be VMDK-only? Or can it still use OS-mounted storage like NFS/iSCSI within the VM?

Regards

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