Azure Files has some limitations which can result in volume mounting issue on ARO clusters

Solution Verified - Updated -

Environment

  • Azure Red Hat OpenShift [ARO]
    • 4.x

Issue

  • I am trying to deploy my application and it is failing with the error below:
chmod: changing permissions of $MOUNT_PATH: Operation not permitted"
  • Why am I not able to mount a volume when using Azure files?

Resolution

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  • While it is still possible to use Azure Files for volume mounting in OpenShift, for deploying applications like PostgreSQL, which requires Hard links to work, the recommendation is to use a different type of storageclass, for example, Azure Disk Storage.

Root Cause

  • According to Microsoft documentation, some applications may not work properly with Azure Files if they rely on unsupported features. Azure Files does not support the following features:

    • SMB Direct
    • SMB Directory Leasing
    • Volume Shadow Copy Service for SMB file share
    • Alternate data streams
    • Extended attributes
    • Object identifiers
    • Hard links
    • Soft links
    • Reparse points
    • Sparse files
    • Short file names (8.3 alias)
    • Compression
    • Named pipes
    • Server service
    • File system transactions (TxF)

Diagnostic Steps

  • Using PostgreSQL database as an example, after creating a persistent volume claim, you may receive an event like the one below:
$ oc set volume deploy postgresql-01-rhel7 --add -t pvc --claim-size=5G --mount-path=/var/lib/pgsql/data
info: Generated volume name: volume-26bh6
deployment.apps/postgresql-01-rhel7 volume updated

$ oc logs postgresql-01-rhel7-68fc6b8cfd-sjxtf
chmod: changing permissions of '/var/lib/pgsql/data/userdata': Operation not permitted

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