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Basic Storage Service Configuration Guide for Block

OceanStor Dorado V3 Series V300R002

This document is applicable to OceanStor Dorado3000 V3, Dorado5000 V3, Dorado6000 V3, and Dorado18000 V3. 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, whose capacities depend on the hot spare policies 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 circuits and internal encryption key of the disk.

    Before using self-encrypting disks to create a disk domain, you must configure the key service. For details, see the Disk Encryption User Guide corresponding to your product model and version.

  • Non-encrypting disk: does not support encryption.

Planning Hot Spare Policies for a Disk Domain

The storage system provides hot spare space to take over data from failed member disks. The following hot spare policies are supported:

  • High

    The capacity of one disk is used as hot spare space if the number of disks in a storage system is less than or equal to 12. The hot spare space increases non-linearly with the number of disks.

  • Low

    The capacity of one disk is used as hot spare space if the number of disks in a storage system is less than or equal to 25. The hot spare space increases non-linearly with the number of disks.

  • None

    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 unused capacity in the storage pool 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 3-1 describes how hot spare space of each pair of controllers changes with the number of disks in V300R002C00.

Table 3-1 Changes of hot spare space

Number of Disks

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

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

[8, 12]

1

1

(12, 25]

2

(25, 50]

3

2

(50, 75]

4

(75, 125]

5

3

(125, 175]

6

(175, 275]

7

4

(275, 300]

8

4

a: Huawei storage systems use RAID 2.0+ virtualization technology. Hot spare capacity is provided by all 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 is equal to the capacity of one SSD and the capacity is provided by all 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 is equal to the capacity of two SSDs.

NOTE:
  • 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 to rebuild data of failed disks only within the disk domain where the hot spare space resides.
  • Table 3-1 lists common capacity changes of hot spare space. The number of disks supported by a storage system and the capacity of their hot spare space depend on actual specifications.

Table 3-2 describes how hot spare space of each pair of controllers changes with the number of disks in V300R002C10 or later.

Table 3-2 Changes of hot spare space

Number of Disks

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

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

[8, 12]

1

1

(12, 25]

2

(25, 75]

3

2

(75, 300]

3

a: Storage systems use RAID 2.0+ virtualization technology. Hot spare capacity is provided by all member disks in each disk domain. Therefore, the hot spare capacity is expressed in 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 is equal to the capacity of one SSD and the capacity is provided by all 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 is equal to the capacity of two SSDs.

NOTE:
  • 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 to rebuild data of failed disks only within the disk domain where the hot spare space resides.
  • Table 3-2 lists common capacity changes of hot spare space. The number of disks supported by a storage system and the capacity of their hot spare space depend on actual specifications.
  • If a storage system is upgraded to V300R002C10 or later, the hot spare space of the disk domains created before the upgrade is calculated in accordance with the rules in the source version. Similarly, the hot spare space of disk domains created after the upgrade is calculated in accordance with the rules in the target version.

Disk Domain Restrictions

NOTE:

For details about disk domain specifications, see "Software Specifications" in the product description specific to your product model and version.

  • A disk domain can contain disks owned by two or four controllers.
  • A disk domain must have at least eight normal member disks if these disks are owned by two controllers, or at least 16 normal member disks if they are owned by four controllers.
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Updated: 2019-07-17

Document ID: EDOC1100049139

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