Mount a File Store on multiple VMs

File Store is designed for shared access, allowing multiple virtual machines (VMs) to mount the same File Store simultaneously. This guide shows you how to mount a File Store on multiple VMs and configure proper access.

Prerequisites

Before you begin:

  • A File Store created and in Available status
  • Two or more VMs in the same VPC and zone as the File Store
  • The File Store endpoint IP (from the File Store status)
  • NFS client installed on all VMs

Architecture

                    File Store
                  (10.100.0.10)
                        |
                        | VPC Network
          ______________|______________
         |                             |
    VM-1 (10.100.0.5)            VM-2 (10.100.0.6)
    /mnt/filestore                 /mnt/filestore
         |                             |
      Shared Data                  Shared Data

All VMs connect to the same File Store endpoint through the VPC network.

Step 1: Verify File Store status

First, verify your File Store is available and get the endpoint IP:

evroc storage filestore get my-filestore

Note the endpoint and exportPath from the output:

status:
  nfs:
    endpoint: 10.100.0.10
    exportPath: /

Step 2: Prepare each VM

On each VM that will mount the File Store:

  1. Install NFS client:

    Ubuntu/Debian:

    sudo apt-get update
sudo apt-get install -y nfs-common

    RHEL/CentOS/Rocky Linux:

    sudo yum install -y nfs-utils

  2. Create mount point:

    sudo mkdir -p /mnt/filestore

Step 3: Mount on each VM

Mount the File Store on each VM using the endpoint IP:

# Replace `<filestore-endpoint>` with your File Store endpoint
sudo mount -t nfs4 -o nfsvers=4.1,_netdev <filestore-endpoint>:/ /mnt/filestore

Verify the mount:

df -h | grep filestore

Step 4: Test shared access

To verify shared access is working:

On VM-1

Create a test file:

echo "Hello from VM-1" | sudo tee /mnt/filestore/shared-test.txt

On VM-2

Read the file:

cat /mnt/filestore/shared-test.txt
# Output: Hello from VM-1

Create another file:

echo "Hello from VM-2" | sudo tee /mnt/filestore/vm2-test.txt

Back on VM-1

List all files:

ls -la /mnt/filestore/
# Output shows both shared-test.txt and vm2-test.txt

Configure automatic mounting

To mount automatically on boot, add entries to /etc/fstab on each VM:

# Replace `<filestore-endpoint>` with your endpoint IP
echo "<filestore-endpoint>:/ /mnt/filestore nfs4 nfsvers=4.1,_netdev 0 0" | sudo tee -a /etc/fstab

Security considerations

Network access

Ensure VMs can reach the File Store endpoint:

  • VMs must be in the same VPC as the File Store
  • By default, security groups already allow NFS traffic (TCP port 2049) within the same VPC
  • Only configure custom security group rules if you have removed default security groups from your VMs

File permissions

File Store uses standard Linux file permissions. To ensure proper access across VMs:

  1. Use consistent user IDs - Ensure users have the same UID across VMs
  2. Set up groups - Use groups for shared access
  3. Configure ACLs - Use Access Control Lists for fine-grained control

Example: Create a shared group

# On each VM, create a group with the same GID
sudo groupadd -g 2000 sharedusers

# Add users to the group
sudo usermod -aG sharedusers username

# Set group ownership on files
sudo chown -R :sharedusers /mnt/filestore/shared-directory
sudo chmod 2775 /mnt/filestore/shared-directory

The 2775 permission sets the setgid bit, ensuring new files inherit the group.

Performance considerations

When multiple VMs access the same File Store:

  • Total throughput is shared across all mounts
  • Concurrent access to the same files may impact performance
  • Caching on each VM may cause temporary inconsistencies

Best practices

  • Distribute read-heavy workloads across multiple File Stores
  • Avoid having multiple VMs write to the same file simultaneously
  • Use application-level locking if coordinating access
  • Consider separate File Stores for different workload types

Troubleshooting

Mount fails on some VMs

If mounting works on some VMs but not others:

  1. Check network connectivity:

    ping <filestore-endpoint>

  2. Verify NFS port is accessible:

    nc -zv <filestore-endpoint> 2049

  3. Check security group rules allow traffic from the VM

Permission denied errors

If you see permission errors:

  1. Verify the mount succeeded:

    mount | grep filestore

  2. Check file permissions:

    ls -la /mnt/filestore

  3. Ensure users have appropriate permissions

Stale file handle errors

If a VM sees "stale file handle" errors:

  1. Unmount the File Store:

    sudo umount /mnt/filestore

  2. Remount:

    sudo mount -t nfs4 -o nfsvers=4.1,_netdev <endpoint>:/ /mnt/filestore

This can happen if the File Store recovers after a failure while a VM had files open.

See Also