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Oracle® VM Server for SPARC 3.6 Administration Guide

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Updated: September 2019
 
 

Virtual Disk Multipathing and NFS

When setting up mpgroup failover with NFS file systems, ensure that you mount the NFS file system with the soft NFS mount option.

By using the soft option, I/O errors are reported to the VDS or VDC, and the VDC sends additional messages to determine whether this is an I/O error or if the entire back end is unavailable. Failover time is proportional to the NFS timeout and the possible retransmissions.

Do not change the timeo NFS mount option from the default value of 60 seconds (timeo=600). A short timeout value such as timeo=40 means that you might encounter spurious I/O errors. For example, when an NFS server or network is unavailable for five seconds and then it returns to operation, I/O errors might be reported because the disruption was not long enough to cause a failover. A longer timeout, such as 60 seconds, masks disruptions that are several seconds long.