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NFS mount:connection timedout intermittently on Virtual Machine/Dom-U under Exadata Environment. (Doc ID 2437869.1)

Last updated on JUNE 11, 2020

Applies to:

Oracle VM - Version 3.4.1 to 3.4.4 [Release OVM34]
Linux x86-64

Symptoms

NFS hang on domU:
An external NAS NFS shared on Dom-0 (X2 and X6), NAS services are provided by dedicated external device storage. One of the NFS share is mounted on Dom-0 Xen hypervisor, which works as expected.
Other shares are mounted on Dom-U: where some are used for RMAN backup and some for DB Import/export. The problem in that situation is that sometimes, a simple “df” command hangs during few seconds, few minutes (!), or even forever.

When there is fail on a NFS mount on a VM, the same mount can be operational on next VM:

Script extract :
####################
let i=1
while [ $i -le $SAUVEBASE ]
do
NFS=/sauvebase/pt_montage_NAS_$i
timeout 5 df -hP $NFS || echo "'date '+%%Y%%m%%d_%%H%%M%%S'';$HOSTNAME;$NFS" >>/exportbase/migration/COS/log/surveillance_nfs.log
let i=i+1
done
####################

This errors are grouped by NAS IP address, not by FS mount. It looks like if NFS mount start to sleep from time to time, and had trouble to wake up at first request, but often ready for next df requests on next mount with same IP address.

Cause

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In this Document
Symptoms
Cause
Solution
References


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