VxVM

Migration Guide: Moving from Veritas Volume Manager (VxVM) to ZFS

Migrating from Veritas Volume Manager (VxVM) to ZFS allows organizations to consolidate volume management and file system features into one solution, simplifying administration and improving performance. While VxVM provides advanced volume management capabilities, ZFS integrates these features natively, including built-in snapshots, compression, and RAID management.

This guide outlines the steps to migrate from VxVM to ZFS, preserving data and configuring ZFS to match the previous VxVM setup.

Why Migrate from VxVM to ZFS?

Key reasons to migrate from VxVM to ZFS include:

• Unified Volume Management and File System: ZFS handles both volume management and file system tasks, eliminating the need for separate tools like VxVM and an external file system (e.g., EXT4 or XFS).
• Data Integrity: ZFS provides end-to-end checksumming, offering superior protection against data corruption.
• Native Snapshots: ZFS natively supports efficient snapshots without requiring third-party tools.
• Built-in RAID Support: ZFS includes RAID-Z, a flexible and reliable RAID system that provides redundancy, eliminating the need for external RAID configurations.

Prerequisites

Before starting the migration, ensure the following:

• Backup Data: Perform a full backup of the data stored on the VxVM volumes. The migration will involve reformatting disks, which will erase data.
• Ensure Disk Space: Prepare new disks for the ZFS pool or ensure enough free space to migrate data from the VxVM volumes.
• Install ZFS Utilities: Install the necessary ZFS packages, depending on the operating system.

For Ubuntu or Debian-based systems:

$ sudo apt install zfsutils-linux

For RHEL-based systems:

$ sudo yum install zfs

Step 1: Prepare the New ZFS Pool

1. Identify Available Disks: Use lsblk or fdisk -l to list available disks and identify the ones to be used for the new ZFS pool.

$ lsblk

2. Create the ZFS Pool: Create the ZFS pool using the identified disks. For a single disk setup:

$ sudo zpool create mypool /dev/sdb

For a mirrored configuration:

$ sudo zpool create mypool mirror /dev/sdb /dev/sdc

For RAID-Z1 (single parity):

$ sudo zpool create mypool raidz /dev/sdb /dev/sdc /dev/sdd

Replace mypool with the desired pool name.

Step 2: Migrate Data from VxVM to ZFS

1. Mount the VxVM Volume: First, mount the VxVM volume using Veritas tools. Ensure that the volume is mounted so the data can be copied.

$ sudo mount /dev/vx/dsk/vgname/volname /mnt/vxvm

2. Copy Data to the ZFS Pool: Use rsync to migrate data from the VxVM volume to the ZFS pool, preserving file attributes, permissions, and symbolic links:

$ sudo rsync -aHAXv /mnt/vxvm/ /mypool/

This command will transfer all data from the VxVM volume at /mnt/vxvm to the ZFS pool at /mypool.

Step 3: Configure ZFS Features

1. Enable Compression: ZFS supports multiple compression algorithms such as lz4 (the default). Enable compression on the ZFS pool:

$ sudo zfs set compression=lz4 mypool

Verify the compression by checking the compression ratio:

$ zfs get compression,compressratio mypool

2. Enable Deduplication (Optional): If deduplication is needed, enable it. However, it is resource-intensive and should be used cautiously:

$ sudo zfs set dedup=on mypool

3. Set Additional Pool Properties: Configure other necessary properties, such as encryption, quotas, or adjusting the mount points.

Step 4: Verifying and Scrubbing the ZFS Pool

1. Check Pool Status: Verify that the ZFS pool is functioning properly by checking its status:

$ sudo zpool status

2. Scrub the Pool: Perform a ZFS scrub to ensure data integrity:

$ sudo zpool scrub mypool

A scrub checks the data for integrity, verifying checksums and repairing any detected issues.

Step 5: Post-Migration Cleanup

After verifying the migration and ensuring the ZFS pool is working as expected, the VxVM volumes can be unmounted, and the partitions can be repurposed.

1. Unmount the VxVM Volume:

$ sudo umount /mnt/vxvm

2. Reclaim or Reformat the VxVM Partition: Use fdisk, parted, or similar tools to delete or reformat the old VxVM partitions as needed.

VxVM to ZFS Command and Utility Mapping