Storage pools are containers of storage resources. The storage resources used by application servers are all from storage pools. Storage pools must be properly planned for better storage utilization.
Planning Disk Types
Disks can be classified into self-encrypting drives (SEDs) and non-encrypting disks. They cannot exist in the same storage pool. SEDs are not sold in the Chinese mainland.
- SED: When data is written into or read from an SED, the data is encrypted or decrypted using the hardware circuits and internal encryption key of the SED.
Before using SEDs to create a storage pool, you must configure the key service. For details, see the disk encryption user guide specific to your product model and version.
- Non-encrypting disk: does not support encryption.
Planning RAID Policies
OceanStor Dorado V6 storage systems use dynamic RAID for redundancy and provide different levels of protection based on the number of parity bits in a RAID group. Table 3-1 describes RAID 5, RAID 6, and RAID-TP provided by storage systems when hot spare space is not considered.
Table 3-1 RAID levels
RAID 5 | 1 | Relatively high. Parity data is distributed on different chunks. In each chunk group, the parity data occupies the space of one chunk. RAID 5 is able to tolerate the failure on only one chunk. If two or more chunks fail, RAID 5 protection can no longer be provided. | 1 |
RAID 6 (default) | 2 | High. Parity data is distributed on different chunks. In each chunk group, the parity data occupies the space of two chunks. RAID 6 is able to tolerate simultaneous failures on two chunks. If three or more chunks fail, RAID 6 protection can no longer be provided. | 2 |
RAID-TP | 3 | High. Parity data is distributed on different chunks. In each chunk group, the parity data occupies the space of three chunks. RAID-TP is able to tolerate simultaneous failures on three chunks. If four or more chunks fail, RAID-TP protection can no longer be provided. | 3 |
The performance delivered by RAID 5, RAID 6, and RAID-TP slightly decreases in sequence as redundancy increases. For different I/O models (random/sequential, read/write), the same RAID level delivers:
- The same performance for random reads and sequential reads.
- Better performance for sequential writes than that for random writes.
Plan the most suitable RAID level based on site requirements, with performance, space efficiency, and reliability considered.
You can configure RAID policies according to the following rules:
- For critical service systems, such as billing systems of operators and class-A financial online transaction systems, you are advised to configure RAID-TP.
- For non-critical service systems, you are advised to configure RAID 6 or RAID 5.
Planning Hot Spare Policies
Hot spare policies None, Low (1 disk) (default for a new storage pool), High (2 disks), Custom (3 disks), Custom (4 disks), Custom (5 disks), Custom (6 disks), Custom (7 disks), and Custom (8 disks) are available.
- RAID 2.0+ allows all member disks in a storage pool to provide hot spare capacity. For ease of understanding, the hot spare capacity is expressed in the number of hot spare disks on DeviceManager.
- Even if the hot spare space is used up, the system can use the free space of the storage pool to reconstruct data, ensuring storage system reliability.
Storage Pool Configuration Rules
- When a storage pool is created on DeviceManager, a disk domain is automatically created within the storage system but is not displayed on DeviceManager. By default, the capacity of a storage pool is equal to the available capacity of the corresponding disk domain.
You can create disk domains and storage pools on the CLI. For details, see the command reference specific to your product model and version.
- An OceanStor Dorado V6 storage system supports one or more storage pools.
- During the initial configuration of a storage system, you can configure that all disks constitute a unique storage pool. After this configuration applies, you do not need to manually create any storage pool.
For details about how to initialize a storage system, see "Logging In and Starting Initialization" in the initialization guide specific to your product model and version.
- You can manually create one or more storage pools. DeviceManager automatically selects appropriate disks to create a storage pool. Alternatively, you can select desired disks to create a storage pool.
- During the initial configuration of a storage system, you can configure that all disks constitute a unique storage pool. After this configuration applies, you do not need to manually create any storage pool.
- A single storage pool requires at least eight normal member disks. If a storage pool spans multiple controller enclosures, the minimum number of disks required for creating the storage pool is calculated as follows: Minimum number of disks = 8 x Number of controller enclosures that the storage pool spans.