Zpool wizard

The Zpool Wizard guides you through the process of creating and configuring a new ZFS pool (zpool) from available disks. A zpool is the foundational storage construct in ZFS. It serves as a logical storage pool that combines multiple physical storage devices (disks) into vdevs (virtual devices), which collectively form the unified zpool. The wizard consists of multiple steps that allow you to configure data groups (vdevs), add optional device groups, adjust pool settings, and enable encryption if required.

Accessing the wizard

1. Navigate to Storage.
2. Click Add zpool.
3. The Zpool creation wizard will launch.
4. Follow the guided steps to configure your zpool.

Zpool configuration steps

Add data group 

In this step, available disks are listed. You can filter only unused disks using the toggle.

1. Select one or more disks from the list.
2. Choose the desired redundancy level for the group:
   • Single - No redundancy. Any disk failure results in data loss.
   • Mirror - Data is stored on multiple disks. Capacity equals the size of one disk per mirror.
     • Mirror (Single Group): All selected disks will be combined into a single mirrored group.
     • Mirror (Multiple Groups): The selected disks will be paired into multiple mirrored groups, each consisting of two disks.
   • Z-1 - Single-parity redundancy. One disk may fail without losing data. A minimum of three disks is required for a RAIDZ-1 group.
   • Z-2 - Double-parity redundancy. Two disks may fail without losing data. A minimum of four disks is required for a RAIDZ-2 group.
   • Z-3 - Triple-parity redundancy. Three disks may fail without losing data. A minimum of five disks is required for a RAIDZ-3 group.
3. Click Add group to add the selected configuration. 
   • The selected data group will appear in the right-hand panel. The total zpool capacity and licensed storage usage are displayed below. 
   • To learn more vdev types, please refer to the following article: Redundancy in Disk Groups 

Add write log (optional)

This feature allows you to configure the write log function with a selected redundancy level (single drive or mirror). The write log utilizes a separate intent log (SLOG) device. A fast SSD/NVMe should be used for this vdev.

1. Select disks from the available list.
2. Choose redundancy type (Single or Mirror) for added reliability.
3. Add the group to the zpool.

Write log groups are displayed separately in the Other groups section.

Key points to consider:

• If multiple log devices are specified, write operations are load-balanced between the devices.
• Log devices can be configured with redundancy by using mirrors to enhance fault tolerance.
• RAIDZ vdev types are not supported for the intent log.

This ensures efficient and reliable write operations while leveraging the selected redundancy level.

Add read cache (optional)

This step allows you to assign SSDs as L2ARC (Level 2 Adaptive Replacement Cache) devices to boost read performance. Adding a read cache improves performance and reduces latency for storage systems under heavy read load. A cache device stores frequently accessed data from the storage pool, providing an additional layer of caching between main memory and disk. These devices cannot be configured as mirrors or RAIDZ groups. A fast SSD/NVMe should be used for this vdev.

1. Select a disk to be used as a cache device. Only Single redundancy is available.
2. Confirm by adding the group.

Key benefits and considerations:

• Cache devices are particularly useful for read-heavy workloads where the working dataset size exceeds the capacity of main memory.
• By utilizing cache devices, a larger portion of the working dataset can be served from low-latency storage, improving performance significantly.
• The greatest performance improvements are seen in workloads characterized by random reads of primarily static content.

Add special devices group (optional)

Special and deduplication vdevs require at least the same level of redundancy as data vdevs. 
Because RAIDZ vdevs do not provide compatible redundancy for these device groups, special vdevs and deduplication vdevs cannot be used in a ZFS pool that contains RAIDZ1, RAIDZ2, or RAIDZ3.

A special devices group stores metadata and small-block data to improve performance. A fast SSD/NVMe should be used for this vdev.

1. Select one or more disks.
2. Choose redundancy (Single or Mirror). The mirror redundancy level is recommended to prevent data loss.
3. Add them as a group.

Key features and benefits:

• Storing metadata on special devices improves performance for metadata-intensive operations, such as file lookups and directory traversals.
• Small files below a certain size threshold can also be stored on these devices, enhancing read and write speeds for such workloads.
• Special devices are particularly beneficial for environments with a large number of small files or high metadata activity.

Using special devices optimizes the overall performance of the ZFS pool by offloading critical metadata and small-file operations to faster storage. 

Add deduplication group (optional)

A deduplication group can be explicitly excluded from a special device group to hold deduplication tables. This allows the deduplication tables to be stored separately from the special device class.

1. Select disks for this purpose. Redundancy can be set to Single or Mirror. The mirror redundancy level is recommended to prevent data loss.
2. Add the group to confirm.

Key features and considerations:

• Storing deduplication tables in a dedicated group improves the efficiency of deduplication processes by isolating them from other metadata operations.
• This configuration provides flexibility in optimizing storage layout based on workload requirements.
• Using a deduplication group is particularly beneficial for systems with high deduplication demands, ensuring better performance and management.

This setup enhances deduplication performance while maintaining a clear separation of metadata and deduplication operations.

Add spare disks (optional)

A spare disk is a special pseudo-vdev used to track available spare devices for a zpool. Using spare disks enhances the storage pool's reliability by enabling seamless drive replacement and reducing the risk of data loss.

1. Select the disk and add it to the Spare group.

Configuration

In this step, you configure the final pool settings:

• Zpool name - Enter a unique name for the zpool for easy identification.
• autoTRIM - If supported by your devices, enable the AutoTRIM feature to reclaim unused space automatically. AutoTRIM helps optimize SSD performance and lifespan by notifying the controller when blocks are no longer in use.
• Initialize the zpool after creation - Writes patterns to unallocated space to avoid initial-write latency, especially in virtualized environments. The process may extend creation time and briefly affect performance.

Proper configuration ensures that the Zpool is tailored to your needs and operates efficiently.

Resource encryption (optional)

Encryption applies to datasets and zvols created in the ZFS pool. The zpool itself remains unencrypted.

1. Enable Configure encryption passphrase. 
2. Select a Default encryption method. 
3. Enter and confirm the passphrase.

Proper configuration ensures that the Zpool is tailored to your needs and operates efficiently.

Note:
• The passphrase cannot be recovered.
• Encrypted resources inherit the passphrase unless changed later.

Summary

The summary page displays the complete zpool configuration before finalization. Click Add zpool to complete pool creation. The wizard will create the zpool with the selected configuration.

Remember:
• Redundancy level cannot be changed after the ZFS pool is created.
• Mixed disk sizes reduce usable capacity to the smallest disk in a vdev.
• SSDs are recommended for write log, special devices, and deduplication groups.
• Encryption passphrases cannot be recovered.