Poor I/O Throughput Across Network in Exalytics OVM Server Causing Slow Performance in Read/Write Operations from VMs to NFS Share (Doc ID 1930365.1)

Last updated on JUNE 25, 2017

Applies to:

Oracle Exalytics Software - Version 1.0.0.3.0 and later
Information in this document applies to any platform.

Symptoms

Poor throughput is observed in I/O across network in DomU, when compared with I/O throughput in Dom0, on an Exalytics Oracle Virtual Machine (OVM) Server.
When running dd test on Dom0 to copy a file to NFS storage and then doing the same for DomU, and comparing the transfer rates, the transfer rates are poor in DomU.
This is causing poor performance when performing read/write operations from VMs to the NFS share.

To confirm the issue, checked the txqueuelen (transfer queue length) value of the VIF (Virtual Interface) of the OVM guest. Ran the following command on Dom0 for the VIF of the DomU:


The txqueuelen results show a low value eg 32. In a correctly configured system, this should be 10000.

Cause

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