Manage storage pools

Users use the block storage resources in the storage cluster through data pools. Data pools define the following data redundancy policies:

• Replication—Protects data by creating multiple replicas of data. The replicas are preferentially distributed on different disks. Data is available as long as one disk is operating correctly with the replica on the disk being integrated. Data durability increases with the number of data blocks at the expense of storage capacity.

• Erasure coding—Protects data by breaking data into blocks, which are expanded and encoded with redundant data pieces and stored across a set of different locations or storage media. The system can recover the data from any combination of a smaller number of those blocks. For example, if n data blocks are encoded with redundant data pieces to generate m parity blocks, data is available when a maximum of m blocks (including data blocks and parity blocks) fail. Encoding refers to the process of generating parity blocks, and decoding refers to the process of restoring data blocks.

Erasure coding provides higher storage usage efficiency and potentially higher fault tolerance than replication. However, erasure coding is more complex, requires more computation, and potentially increases the time to recover from failure. Erasure coding policies apply to read-only data and cold data such as VM backup files and VM templates.

Create a storage pool

Perform this task to create a block storage pool. After that, users can use the block storage resources in the cluster.

 

·          You can create a maximum of five data pools. ·          You cannot create erasure coding data pools when the number of storage nodes is smaller than four.

 

Procedure

1. From the navigation pane, select ONEStor > Pool Info.

2. Click Create.

3. Configure the parameters as described in "Parameters"

4. Click OK.

Parameters

• Storage Pool Name: Enter a name for the block storage pool.

• Node Pool: Select a node pool for creating the storage pool.

• Disk Pool: Select a disk pool for creating the storage pool.

• Redundancy Policy: Configure the redundancy policy for the storage pool:

• Replication: Select this option to enable replication. Replication protects data by creating multiple replicas of data. Data is available as long as one replica is available.

• Replicas: Set the number of replicas. The more replicas you set, the more secure the data, and the more storage capacity is required.

• Single Replica Readable: Select whether to enable Single Replica Readable. If you select yes, you can only read the replica when only one replica is available.

• Erasure Coding: Select this option to enable erasure coding. In case that some of the data blocks or parity blocks are lost, the missing data can be calculated from the remaining data blocks and parity blocks.

To use erasure coding, select Erasure Coding and set the following coding parameters:

• Data Blocks—Set the number of blocks into which data is divided.

• Parity Blocks—Set the ratio of parity blocks to the maximum number of damaged nodes. For example, if you set the ratio to 3:1, the number of parity blocks is 3 and the damaged node number limit is 1.

• Chunk Size—Set the chunk size for data blocks. To ensure load balancing between nodes, data will be divided into multiple blocks in the same size. To ensure service performance, set the chunk size according to actual service conditions.

• Stripe Size—Basic unit used for encoding and decoding. The stripe size is determined by the number of data blocks and the chunk size.

• Data Writing Policy—Select a data writing control policy. Options include Data Availability and Service Continuity. If Data Availability is selected, the system writes data only when a minimum of one copy of redundant data exists. If Service Continuity is selected, the system writes data even if no redundant data exists. In this situation, system exceptions and data loss might occur.

Delete a storage pool

1. From the navigation pane, select ONEStor > Pool Info.

2. Click Delete in the Actions column for a storage pool.

3. In the dialog box that opens, click OK.

Edit the number of replicas

1. From the navigation pane, select ONEStor > Pool Info.

2. Click the  icon to the right of the number of replicas in the Redundancy Policy column for the target storage pool.

3. Edit the number of replicas as needed, click OK.

View storage volumes in a storage pool

1. From the navigation pane, select ONEStor > Pool Info.

2. Click Volumes in the Actions column for the target storage pool.

View detailed information about a storage pool

1. From the navigation pane, select ONEStor > Pool Info.

2. Click  to the left of the target storage pool.