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william_Johnny
Contributor
Contributor

vSphere Replication very slow for certain VMs

Hi All,

I encountered some slow replication issue on some of the VM.

Based on my performance benchmark, a "normal" vm with 50GB used space will take 20 min to replicate between 2 sites. The "problem" VM with total used space of 20GB took between 1 hour to 1 hours 45 min to complete the replication ( I did multiple tests on the same VM, the performance varies between these range). I did some troubleshooting by monitor the vmkernel port dedicated for the vSphere Replication on the source ESXi, it was observed that there were data transmitted in the first 15 min. After this point, there is 0 activities in the VR's vmkernel port. At this point, the replication progress is around 20%. This went on until the replication completed at 100%. Based on the vmkernal port monitoring, it seem to be that the replication completed in the first 15 min and then  wait for something to continue.
Anyone has any clue about this behavior? Why only certain vm exhibited this strange behavior?

Thanks,

Dan

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T180985
Expert
Expert

Not sure what you have checked so far but is there anything that stands out in the logs?

vSphere Replication Log Files

The initial replication should take some time but after that its just delta changes so unless you have alot of data change, it should be a relatively fast replication

Please mark helpful or correct if my answer resolved your issue. How to post effectively on VMTN https://communities.vmware.com/people/daphnissov/blog/2018/12/05/how-to-ask-for-help-on-tech-forums
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william_Johnny
Contributor
Contributor

Hi T180985,

Thanks for the feedback. I will take a look at those VR logs and see it I can find some clue.

Interesting is that it only happened to certain VM. The rest are working as expected.

I will provide further update.

DAN

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