Create RAID Group

This function creates a RAID group.

A RAID group is a group of drives that configure a RAID level.

Features and Required Number of Drives for Each RAID Level

The following table shows the features and the required number of drives for each RAID level.

Actual RAID group configurations (or the number of available drives) vary depending on the maximum number of drives that can be installed in the storage system.

*1	:	The RAID levels in the table above, setting value fields, and display contents fields for descriptions are written according to how they actually appear in Web GUI. Other fields and descriptions in this manual use "RAIDxx" as an abbreviation for the RAID levels.
*2	:	D: Data drives, M: Mirror drives, P: Parity drives, HS: Hot Spares

Restrictions for RAID6-FR

The following restrictions apply to RAID groups (hereinafter referred to as "Fast Recovery RAID groups") that were created with RAID6-FR and volumes created in those RAID groups.

• The following operations that use LDE cannot be performed for Fast Recovery RAID groups.

  • Changing the RAID level to "RAID6-FR"

  • Changing the RAID level from "RAID6-FR"

  • Expanding the RAID group capacity by adding drives

• "Standard (including concatenation volumes by means of LUN Concatenation)" and ODX Buffer volumes can be created in the Fast Recovery RAID group.

• Encrypted volumes can be created in the Fast Recovery RAID groups. However, encrypting volumes that exist in Fast Recovery RAID groups is not allowed.

• The Stripe Depth for a Fast Recovery RAID group is fixed at "64KB".

• The Copybackless function is not performed when the first drive fails in a Fast Recovery RAID group. A high-speed rebuild is performed in a hot spare area within the RAID group, and when the failed drive is exchanged for a normal drive, copyback is performed.

Restrictions for RAID5+0

The following restrictions apply to RAID groups that are created with "RAID5+0".

• The following operations that use LDE cannot be performed.

  • Changing the RAID level to "RAID5+0"

  • Changing the RAID level from "RAID5+0"

  • Expanding the RAID group capacity by adding drives

• The Stripe Depth for a new RAID group is fixed at "64KB".

The Maximum Number of RAID Groups for Each Model

The maximum number of RAID groups varies depending on each model. The following table shows the maximum number of RAID groups for each model.

Drive Combinations That Can Configure a RAID Group

The following table shows the drive combinations that can configure a RAID group.

OK: RAID groups can be created    OK (but not recommended): RAID groups can be created, but not a recommended configuration   NG: RAID groups cannot be created

Availability of Executions in the Default Role

Refer to "User Roles and Policies" for details on the policies and roles.

In this screen, create a RAID group.

There are two methods to create RAID groups: automatic drive selection and manual drive selection.

New RAID Group

Input the name of the RAID group that is to be newly created and select the create mode.

Automatic Setting

Naming Conventions for Creating RAID Groups

• When creating multiple RAID groups at a time, a name is automatically added to a RAID group with the specified "Name" and a suffix number "x" (serial numbers starting with "0").

  (Example) Specified RAID group name: RAIDGroup_aaaa (14 characters) → Name for created RAID group: RAIDGroup_aaaa0, RAIDGroup_aaaa1, etc.

• When the RAID group name including the suffix number "x" has more than 16 characters, the excess number of characters is deleted from the "Name", starting with the last character and a suffix number "~x" will be added. Then, the name will contain only 16 characters.

  (Example) Specified RAID group name: RAIDGroup_aaaabb (16 characters) → Name for created RAID group: RAIDGroup_aaaa~0, RAIDGroup_aaaa~1, etc.

• When a RAID group name including the suffix number already exists, the suffix number is increased by one (+1). The suffix number is increased by one (+1) until no RAID group names overlap.

Manual Setting

Drive Configuration for Fast Recovery RAID Groups

The drive layout in the storage system is the same as "RAID6". When using automatic configuration, the drive configuration that satisfies the specified capacity is determined according to the following order.

*1

:

Fast Recovery RAID groups are described as "Redundant sets + HS".      RAID6 ((Number of data drives (D) + Number of parity drives (P)) × Number of redundant sets + Number of hot spares (HS))                              ↑                          Redundant sets      (Example) "RAID6 ((3D+2P)x2+1HS)" is described as "(3D+2P)x2+1HS".

*2	:	The ratio of the user capacity to physical drive capacity.
*3	:	Rate when the rebuilding speed for the basic "RAID6 (D+P)" configuration is "1". The rate varies depending on the workload of the storage system and system environment.

Advanced Setting

Perform the advanced settings for RAID groups

Available Stripe Depth Value

The Stripe Depth values available for each RAID level are as follows:

Restrictions for Stripe Depth Modification

Note that the following restrictions apply to a RAID group whose Stripe Depth has been changed and volumes created for such RAID group.

• The Stripe Depth of the RAID groups already created cannot be changed .

• When selecting drives automatically to create a RAID group, the Stripe Depth cannot be changed.

• The capacity cannot be expanded if the Stripe Depth of the RAID group has been changed (LDE is not available).

• Encryption cannot be performed for volumes that are created in a RAID group whose Stripe Depth has been changed.

Drive Selection

Drives can be selected from the list or the installation image. To switch between the list and the installation image, click the tab.

[Tabular] Tab

Click the [Tabular] tab to select drives from the list. Only unused drives are displayed on the list.

There are conditions for the ETERNUS DX8100 S4/DX8900 S4 drive layout. Refer to "Conditions for the ETERNUS DX8100 S4/DX8900 S4 Drive Layout" for details. Note that these conditions are not applied to other models.

[Graphic] Tab

Click the [Graphic] tab to select drives from the drive installation image. The installation images of all the drives installed in the storage system are displayed. Checkboxes are displayed for unused drives.

There are conditions for the ETERNUS DX8100 S4/DX8900 S4 drive layout. Refer to "Conditions for the ETERNUS DX8100 S4/DX8900 S4 Drive Layout" for details. Note that these conditions are not applied to other models.

Conditions for the ETERNUS DX8100 S4/DX8900 S4 Drive Layout

The drive layout to configure RAID groups in the ETERNUS DX8100 S4/DX8900 S4 must satisfy the conditions described below.

RAID groups cannot be created if the required conditions are not satisfied.

For the ETERNUS DX8100 S4

For the ETERNUS DX8900 S4

*1	:	DEs under different CEs have different numbers as the first digit of the DE number.
*2	:	"SAS cascade" for the ETERNUS DX8900 S4 refers to DEs that are attached to one drive interface port. The DEs that are allocated to the same SAS cascade configuration are as follows:      DE#x1, DE#x2, and DE#x3 that are connected to CE#x/DI Port#0 (x: 0 - B)      DE#x4, DE#x5, DE#x6, and DE#x7 that are connected to CE#x/DI Port#1 (x: 0 - B)      DE#x8, DE#x9, DE#xA, and DE#xB that are connected to CE#x/DI Port#2 (x: 0 - B)      DE#xC, DE#xD, DE#xE, and DE#xF that are connected to CE#x/DI Port#3 (x: 0 - B)      (Example) DE#01, DE#02, and DE#03 that are connected to CE#0/DI Port#0 are on the same SAS cascade.

DE selection list box

*1

:

Only 2.5" drives can be installed.

Automatically Selecting Drives to Create RAID Groups

1. Click [Create] in [Action].

2. Select "Automatic" for "Create Mode".

3. Specify the RAID group detailed information, and click the [Create] button.

   → A confirmation screen appears.

   Caution

   • An error screen appears in the following conditions:

     • The "Name" overlaps with an existing name (when one RAID group is created)

     • The "Name" does not satisfy the input conditions

     • RAID groups cannot be created by using the drives that are installed in the storage system

4. Click the [OK] button.

   → RAID group creation starts.

5. Click the [Done] button to return to the [RAID Group] screen.

Manually Selecting Drives to Create RAID Groups

1. Click [Create] in [Action].

2. Select "Manual" for "Create Mode".

3. Specify the RAID group detailed information.

4. Select drives using a list of the drives or the installation location image.

   Note

   • When the number of drives for each RAID level and the number of selected drives does not match, the [Create] button cannot be clicked.

5. Click the [Create] button.

   → A confirmation screen appears.

   Caution

   • An error screen appears in the following conditions:

     • The "Name" overlaps with an existing RAID group name

     • The "Name" does not satisfy the input conditions

     • The drive layout does not satisfy the required conditions

       (Refer to "Conditions for the ETERNUS DX8100 S4/DX8900 S4 Drive Layout" for details.)

     • The specified Stripe Depth is not allowed for the RAID level

6. Click the [OK] button.

   → RAID group creation starts.

7. Click the [Done] button to return to the [RAID Group] screen.