# Instance Creation Failing due to Failed NFS Mount

## Problem

* When attempting to create a VM on a compute host, the following error is observed in the UI or through the CLI:

```ruby
Exceeded maximum number of retries. Exceeded max scheduling attempts 3 for instance [INSTANCE_ID]. Last exception: Unexpected error while running command.
Command: mount -t nfs -o vers=3,proto=tcp,lookupcache=pos,nolock,noacl [NFS_SERVER_IP]

Traceback (most recent call last):
  File "/var/lib/openstack/lib/python3.10/site-packages/nova/conductor/manager.py", line 690, in build_instances
    scheduler_utils.populate_retry(
  File "/var/lib/openstack/lib/python3.10/site-packages/nova/scheduler/utils.py", line 1017, in populate_retry
    raise exception.MaxRetriesExceeded(reason=msg)
nova.exception.MaxRetriesExceeded: Exceeded maximum number of retries. Exceeded max scheduling attempts 3 for instance [INSTANCE_ID]. Last exception: Unexpected error while running command.
Command: mount -t nfs -o vers=3,proto=tcp,lookupcache=pos,nolock,noacl [NFS_SERVER_IP]:/nfs/share /local/mount/point
Exit code: 32
Stdout: ''
Stderr: 'mount: /local/mount/point: bad option; for several filesystems (e.g. nfs, cifs) you might need a /sbin/mount.<type> helper program.\n'
```

* VM migration fails due to an NFS mount error on the destination host. During the migration process, the destination host is unable to mount the required NFS share.

## Environment

* Platform9 Private Cloud Director - v2025.4 and Higher
* Self Hosted Private Cloud Director Virtualization – v2025.4 and Higher
* Component - Compute Service

## Cause

* The failure occurred because the `nfs-common` package *(which provides the mount.nfs helper utility)* was not installed or not properly configured on the destination host. As a result, the system was unable to execute the mount command for the NFS share during the VM migration process. This led to a failure in mounting the NFS volume required for shared storage, preventing the migration from completing successfully.

## Diagnostics

1. NFS Volume is not getting created in hosts with the aforementioned error.
2. Attempt manual NFS mount on the destination host.

```bash
sudo mount -t nfs -o vers=3 [NFS_SERVER_IP]:/nfs/share /local/mount/point

mount: /local/mount/point: bad option; for several filesystems (e.g. nfs, cifs) you might need a /sbin/mount.<type> helper program.
```

3. Check if the required package is installed.

```bash
dpkg -l | grep nfs-common
```

## Resolution

1. Manually install nfs-common package on the affected host.

```bash
sudo apt install -y nfs-common
```

## Validation

1. Check if the the volumes are getting properly mounted in the affected hosts.

```bash
$ sudo mount | grep "</NFS/SHARE>"

[NFS_SERVER_IP]:/nfs/share on /local/mount/point/[UUID] type nfs (rw,vers=3,proto=tcp,...)
```

2. If these steps prove insufficient to resolve the issue, reach out to the Platform9 Support Team for additional assistance.


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