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Basic Storage Service Configuration Guide for Block

OceanStor V5 Series V500R007

This document is applicable to OceanStor 5110 V5, 5300 V5, 5500 V5, 5600 V5, 5800 V5, 6800 V5, 5300F V5, 5500F V5, 5600F V5, 5800F V5, 6800F V5, 18500 V5, 18800 V5, 18500F V5, and 18800F V5. It describes the basic storage services and explains how to configure and manage them.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Planning Disk Domains

Planning Disk Domains

A disk domain provides storage space for storage pools. The storage tiers and available capacities of storage pools depend on the disk types, capacity, and hot spare policy of the disk domain.

Planning Disk Types for a Disk Domain

Disks can be classified into self-encrypting and non-encrypting disks. They cannot exist in the same disk domain. Self-encrypting disks are not sold in mainland China.
  • Self-encrypting disk: When data is written into or read from a self-encrypting disk, the data is encrypted or decrypted using the hardware circuit and internal encryption key of the disk.

    Before using self-encrypting disks to create an encrypted disk domain, install and configure the key service by following instructions in the Disk Encryption User Guide specific to your product model and version.

  • Non-encrypting disk: Non-encrypting disks are common disks that do not support the encryption function.

Disks can be classified into SSDs, SAS disks, and NL-SAS disks.

A disk type in a disk domain corresponds to a storage tier in a storage pool. If the disk domain does not have a specific disk type, the corresponding storage tier cannot be created for a storage pool.

Table 3-5 describes the mapping between disk types and storage tiers.

Table 3-5 Mapping between disk types and storage tiers

Disk Type

Storage Tier

SSD

High-performance tier

SAS disk

Performance tier

NL-SAS disk

Capacity tier

Planning Hot Spare Policies for a Disk Domain

To prevent data loss or performance deterioration caused by a member disk failure, a storage system uses hot spare space to take over data from the failed member disk. The following hot spare policies are supported:

  • High

    The capacity of one disk is used as hot spare space if the number of disks at a storage tier is equal to or fewer than 12. The hot spare space non-linearly increases as the number of disks increases.

  • Low

    The capacity of one disk is used as hot spare space if the number of disks at a storage tier is equal to or fewer than 25. The hot spare space non-linearly increases as the number of disks increases.

    Number of disks of which capacity is used as hot spare space in a low hot spare policy = Number of disks of which capacity is used as hot spare space in a high hot spare policy/2 (rounded up)

  • None (not supported by 18000 or 18000F series storage systems)

    The storage system does not provide any hot spare space. In the event a member disk in a disk domain fails, the storage system uses the free capacity in the disk domain for reconstruction. If the free capacity in the disk domain is insufficient, the storage system uses the unallocated capacity in storage pools for reconstruction. If reconstruction fails, the disk domain will change to the Degrade state, which will cause the read/write performance to deteriorate, affecting the storage system reliability.

Table 3-6 describes how hot spare space changes for a single engine with the number of disks in V500R007C30 and earlier (excluding V500R007C30SPH105). The hot spare space changes at a storage tier are used as an example here. The hot spare space changes at different storage tiers are the same.

Table 3-6 Changes of hot spare space for a single engine

Number of Disks

Number of Disks of Which Capacity Is Used as Hot Spare Space in a High Hot Spare Policya

Number of Disks of Which Capacity Is Used as Hot Spare Space in a Low Hot Spare Policya

(1, 12]

1

1

(12, 25]

2

(25, 50]

3

2

(50, 75]

4

(75, 125]

5

3

(125, 175]b

6

(175, 275]

7

4

(275, 375]

8

a: Huawei storage systems use RAID 2.0+ virtualization technology. Hot spare capacity is provided by member disks in each disk domain. Therefore, the hot spare capacity is expressed in the number of disks in this table.

For example, if a disk domain is composed of 12 SSDs and the high hot spare policy is used, the hot spare space occupies the capacity of one SSD and the capacity is provided by member disks in the disk domain. If a disk domain is composed of 13 SSDs and the high hot spare policy is used, the hot spare space occupies the capacity of two SSDs.

b: When the number of disks at a storage tier reaches 175, the storage tier uses the capacity of one disk in every 100 additional disks as the hot spare space in a high hot spare policy.

Table 3-7 describes how hot spare space changes for a single engine with the number of disks in V500R007C30SPH105 and V500R007C50 and later. The hot spare space changes at a storage tier are used as an example here. The hot spare space changes at different storage tiers are the same.

Table 3-7 Changes of hot spare space for a single engine

Number of Disks

Number of Disks of Which Capacity Is Used as Hot Spare Space in a High Hot Spare Policya

Number of Disks of Which Capacity Is Used as Hot Spare Space in a Low Hot Spare Policya

(1, 12]

1

1

(12, 25]

2

(25, 125]b

3

2

(125, 325]

4

……

a: Huawei storage systems use RAID 2.0+ virtualization technology. Hot spare capacity is provided by member disks in each disk domain. Therefore, the hot spare capacity is expressed in the number of disks in this table.

For example, if a disk domain is composed of 12 SSDs and the high hot spare policy is used, the hot spare space occupies the capacity of one SSD and the capacity is provided by member disks in the disk domain. If a disk domain is composed of 13 SSDs and the high hot spare policy is used, the hot spare space occupies the capacity of two SSDs.

b: When the number of disks at a storage tier reaches 125, the storage tier uses the capacity of one disk in every 200 additional disks as the hot spare space in a high hot spare policy.

NOTE:
  • After a storage system is upgraded to V500R007C30SPH105 or V500R007C50 or later, hot spare space in the disk domains created before the upgrade will be re-calculated according to the rules in Table 3-7.
  • Number of Disks in the above tables refers to the number of same-type disks owned by a same engine. If you select disks from multiple engines to create a disk domain, calculate the number of disks used for hot spare space on each engine and sum up the values.
  • For 18000 and 18000F series storage systems, the high hot spare policy is used by default. You are not allowed to modify the hot spare policy on DeviceManager. To modify the hot spare policy, run the change disk_domain general command in the CLI.
  • When you are creating a disk domain, ensure that the disks used to provide hot spare space are sufficient.
  • Hot spare space can be used for a specific disk domain only.
  • Common capacity changes of the hot spare space are listed in this section. The number of disks supported by a storage system and the capacity of hot spare space are based on actual specifications.

Recommended Configurations for Disks in a Disk Domain

You are advised to configure a maximum of 100 disks for each tier in a disk domain. For example, if the number of disks on a tier is D (divide D by 100 and then round off the result to N and the remainder is M), you can refer to the following configurations:

  • If D ≤ 100, configure all disks on this tier in one disk domain.
  • If D > 100, create N+1 disk domains and evenly distribute all disks to the N+1 disk domains. That is, the number of disks in each disk domain is D/(N+1). In addition, it is recommended that disk enclosures be fully configured.
  • For SmartTier, it is recommended that a maximum of 100 disks be configured for each tier in a disk domain. The configuration of disks on each tier also follows the preceding principle.

Example 1: The total number of SSDs in a storage system is 328, which is the value of D. (Divide 328 by 100. Round off the result to 3, which is the value of N. The remainder is 28, which is the value of M). You are advised to configure four disk domains, each of which contains 328/4 = 82 SSDs.

Example 2: The total number of SSDs in a storage system is 223, which is the value of D. (Divide 223 by 100. Round off the result to 2, which is the value of N. The remainder is 23, which is the value of M). You are advised to configure three disk domains, each of which contains 223/3 = 74.3 disks. In this case, two disk domains are configured with 74 disks respectively and the other disk domain is configured with 75 disks.

Example 3: If a disk domain consists of SSDs, SAS disks, and NL-SAS disks, for SmartTier, the number of disks of each type cannot exceed 100.

NOTE:

If a project requires a disk domain containing over 100 disks to meet capacity and service planning requirements, contact Huawei technical support engineers for evaluation.

Planning Capacity for a Disk Domain (OceanStor 5000, 5000F, 6000, and 6000F Series Storage Systems)

The space of a storage pool originates from a disk domain. Therefore, the capacity of the disk domain determines the available capacity of the storage pool. When planning the minimum capacity for a disk domain, you must set related parameters including the hot spare policy, RAID policy, and storage media to ensure that the disk domain can meet capacity requirements. Table 3-8 describes the minimum number of disks required for a disk domain (for a single controller enclosure).

Table 3-8 Minimum number of disks required for a disk domain (for a single controller enclosure)

RAID Policy

Minimum Number of Disks in a Disk Domain

RAID 0

4

RAID 1 (2D)

4

NOTE:

If the number of SSDs in a disk domain is two or three, you are advised to configure RAID 1 (2D) for the high-performance tier.

RAID 1 (4D)

4

RAID 10

4

RAID 3 (2D+1P)

4

RAID 3 (4D+1P)

6

RAID 3 (8D+1P)

10

RAID 5 (2D+1P)

4

RAID 5 (4D+1P)

6

RAID 5 (8D+1P)

10

RAID 6 (2D+2P)

5

RAID 6 (4D+2P)

7

RAID 6 (8D+2P)

11

RAID 6 (16D+2P)

19

RAID 50 (2D+1P) x 2

7

RAID 50 (4D+1P) x 2

11

RAID 50 (8D+1P) x 2

19

NOTE:
  • The previous table only lists the minimum number of disks required in standard RAID levels. The storage system also supports flexible configuration. For a flexibly configured RAID policy xD+yP, the minimum disk number is x + y + z when the number of required hot spare disks is z. The z value is determined by the hot spare policy and disk quantity.
  • The disks listed in the Minimum Number of Disks in a Disk Domain column of the preceding table must be provided by the same controller enclosure. If the disks that you use to create a disk domain are provided by different controller enclosures, ensure that the number of disks on each controller enclosure meets the disk number requirements (minimum number of disks).
  • Under Specify disk type in the Create Disk Domain window, you can select the following three types of disks: High-Performance tier: SSD, Performance tier: SAS, and Capacity tier: NL-SAS. If you select only one type, at least four disks of this type are required for each controller enclosure. If you select two or three types of disks, at least two SSDs, four SAS disks, and four NL-SAS disks are required for each controller enclosure.
  • RAID 0 can only be configured using the CLI. For details, see the command reference specific to your product model and version.

Planning Capacity for a Disk Domain (OceanStor 18000 and 18000F Series Storage Systems)

The space of a storage pool originates from a disk domain. Therefore, the capacity of the disk domain determines the available capacity of the storage pool. When planning the minimum capacity for a disk domain, you must set related parameters including the hot spare policy, RAID policy, and storage media to ensure that the disk domain can meet capacity requirements. Table 3-9 describes the minimum number of disks required for a disk domain (for a single engine).

Table 3-9 Minimum number of disks required for a disk domain (for a single engine)

RAID Policy

Minimum Number of Disks in a Disk Domain (SSD)

Minimum Number of Disks in a Disk Domain (SAS)a

Minimum Number of Disks in a Disk Domain (NL-SAS)a

RAID 0

6

8

8

RAID 1 (2D)

6

8

8

RAID 1 (4D)

6

8

8

RAID 10

6

8

8

RAID 3 (2D+1P)

6

8

8

RAID 3 (4D+1P)

6

8

8

RAID 3 (8D+1P)

10

10

10

RAID 5 (2D+1P)

6

8

8

RAID 5 (4D+1P)

6

8

8

RAID 5 (8D+1P)

10

10

10

RAID 6 (2D+2P)

6

8

8

RAID 6 (4D+2P)

7

8

8

RAID 6 (8D+2P)

11

11

11

RAID 6 (16D+2P)

19

19

19

RAID 50 (2D+1P) x 2

7

8

8

RAID 50 (4D+1P) x 2

11

11

11

RAID 50 (8D+1P) x 2

19

19

19

a: only applies to the 18000 series storage systems.

NOTE:
  • The previous table only lists the minimum number of disks required in standard RAID levels. The storage system also supports flexible configuration. For a flexibly configured RAID policy xD+yP, the minimum disk number is x + y + z when the number of required hot spare disks is z. The z value is determined by the hot spare policy and disk quantity.
  • The disks listed in the Minimum Number of Disks in a Disk Domain column of the preceding table must be provided by the same engine. If the disks that you use to create a disk domain are provided by different engines, ensure that the number of disks on each engine meets the disk number requirements (minimum number of disks).
  • Under Specify disk type in the Create Disk Domain window, you can select the following three types of disks: High-Performance tier: SSD, Performance tier: SAS, and Capacity tier: NL-SAS. If you select only High-Performance tier: SSD, at least six disks of this type are required for each engine. If you select only Performance tier: SAS or Capacity tier: NL-SAS, at least eight disks of this type are required for each engine. If you select two or three types of disks, at least six SSDs, eight SAS disks, and eight NL-SAS disks are required for each engine.
  • RAID 0 can only be configured using the CLI. For details, see the command reference specific to your product model and version.

Suggestions

Refer to the following suggestions to plan disk domains:

  • When creating a disk domain, manually select disks to ensure that all disks are from the same engine. Create disk domains on one engine to reduce the probability of disk failure and improve the read and write performance of disks.
  • You are advised to use disks of the same type, capacity, and rotating speed (except SSDs) in the same storage tier in a disk domain. If disk capacities are not the same, disks with large capacities may not be used effectively. If disk rotating speeds are different, performance may deteriorate.
  • You are advised not to configure the disks from high-density and common disk enclosures in the same disk domain. Otherwise, storage system performance will be adversely affected.
  • You are advised to create different disk domains for the block and file storage service. If you want to configure both block and file storage service in one disk domain, contact Huawei technical support engineers to help you evaluate the practicality.
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Updated: 2019-08-30

Document ID: EDOC1000181506

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