Expand RAID Group

Overview

This function adds drives to the existing RAID group by using the Logical Device Expansion (LDE) function to dynamically expand the RAID group capacity. This function can also dynamically change the RAID level of an existing RAID group.

RAID group expansion provides the following features without stopping the storage system operation:

  • RAID group expansion add drives to the existing RAID group in units of one drive. This enables capacity expansion of RAID groups with smaller number of drive expansion.

  • RAID groups can be expanded and any existing data in these RAID groups is retained.

Requirements for RAID Groups to Expand Capacity

  • The RAID group status is "Available"

  • Standard type volumes, SDVs, or SDPVs are registered

  • WSVs are not registered

  • Not registered in TPP

  • Not registered in FTRP

  • Not registered as an REC Disk Buffer

  • Not registered as an Extreme Cache Pool

  • RAID level is not "RAID5+0" or "RAID6-FR"

  • The RAID group is not blocked

  • Rebuild, copyback, or redundant copy is not being performed

  • The Controlling CM is not being changed

  • One of the following functions is not being performed for the volume that is registered in the RAID group

  • Storage Migration paths are not created in the volume that is registered in the RAID group

  • Is not a RAID group with the stripe size expanded (*1)

    *1  :  A RAID group with more than 128KB of "Stripe Depth" specified in the [RAID Group Detail] screen of [RAID Group (Basic Information)]. Note that the Stripe Depth value for RAID1 cannot be changed.

Requirements for the Storage System to Expand Capacity

  • The cache mode is "Write Back Mode"

  • All the CMs are in the normal state

  • The battery status is "Normal"

  • LDE is not being performed

  • RAID group diagnosis is not being performed

  • Disk diagnosis is not being performed

  • Application of controller firmware is not being performed

  • Application of disk firmware is not being performed

Caution

  • Before expanding the RAID group, back up data in all the logical volumes that are stored in the target RAID group to a different location (if not, data cannot be recovered when expansion fails). If expansion fails, data can be recovered from the backed up data.

  • The expansion of capacity can only be performed for one RAID group at a time.

  • RAID group expansion cannot be suspended.

  • The following operations cannot be used for RAID groups in which RAID group expansion is being performed:

    • Format Volume

    • Create Volume

    • Encrypt Volume

    • RAID Migration for the volume

    • Expand Volume

    • Hot Preventive Maintenance

    • RAID Group Diagnosis

    • Disk Diagnosis

  • For some combinations of RAID levels, LDE cannot be used. Refer to "Availability of LDE for Each Combination of RAID Levels" for details.

Note

  • RAID groups can be expanded when the RAID group capacity after performing expansion is the same or larger than the current RAID group capacity.

  • When expanding the drive capacity that configures a RAID group, use the [Start RAID Migration] function instead of this function.

Availability of LDE for Each Combination of RAID Levels (LDE is Available: )

The following table shows the availability of LDE functions (changing RAID levels or capacity expansion by adding drives).

 RAID level after changing
RAID0 RAID1 RAID1+0 RAID5 RAID5+0 RAID6 RAID6-FR
RAID level before changing RAID0

RAID1

 
RAID1+0

RAID5

RAID5+0

RAID6

RAID6-FR

User Privileges

Availability of Executions in the Default Role

Default role Availability of executions
Monitor  
Admin
StorageAdmin
AccountAdmin  
SecurityAdmin  
Maintainer

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

Display Contents

In this screen, the RAID groups for which capacity is to be expanded are displayed.

Setting RAID Group

Item Description

Name

The RAID group name is displayed.

RAID Level

The current RAID level is displayed.

High Performance (RAID1+0)

High Capacity (RAID5)

High Reliability (RAID6)

Mirroring (RAID1)

Striping (RAID0)

Minimum Capacity per RAID Group

The current capacity of the RAID group is displayed.

Settings

Manual Setting

Item Description Setting values

RAID Level after expand

Select the RAID level after expansion is performed.

The selectable RAID levels are displayed as options in the list box.

High Performance (RAID1+0)

High Capacity (RAID5)

High Reliability (RAID6)

Striping (RAID0)

The currently set RAID level is the default value. However, "High Performance (RAID1+0)" is displayed if the current RAID level is RAID1.

RAID Group Capacity after expand

The RAID group capacity after expansion is displayed.

The capacity is automatically calculated from the selected RAID level and drives.

If no drives are selected or if RAID groups cannot be configured with the selected drives, a "-" (hyphen) is displayed.

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.

Requirements for selecting drives
  • The drive requirements for adding to RAID groups are listed below.

    • The drive status is "Present"

    • The drives are not registered in any RAID group, TPP, FTRP, REC Disk Buffer, or Extreme Cache Pool

    • The drives are not registered as hot spares

    • The drive type (Online/Nearline/SSD/Online SED/Nearline SED/SSD SED) must be the same

      (Although "Online" type drives and "Nearline" type drives can be used in the same RAID group, using only "Online" type drives or using only "Nearline" type drives is recommended. Also, "Online SED" type drives and "Nearline SED" type drives can be used in the same RAID group, but using only "Online SED" type drives or using only "Nearline SED" type drives is recommended. This is because the available capacity and the access performance may be reduced when these drives are used in the same RAID group.)

    • Drives that have the same or larger capacity than the drive with the smallest capacity in the expansion target RAID group

    • If "RAID1+0" or "RAID5" is selected for the RAID level after an expansion, drives that are 6 TB or larger (except SSDs and SSD SEDs) cannot be specified.

      (Note that when drives that are 6 TB or larger (except SSDs and SSD SEDs) already exist in the RAID group before the expansion, these drives can be used after changing the RAID level.)

  • Drive recommendations for adding to RAID groups are listed below.

    • Use drives that have the same capacity and speed as the drives that configure the expansion target RAID group. If drives of different capacities exist in a RAID group, the smallest capacity becomes the standard for the RAID group after expansion, and all other drives are regarded as having the same capacity as the smallest drive. In this case, the remaining drive space is not used. In addition, if drives of different speeds exist in a RAID group, the access performance of the RAID group is reduced by the slower drives.

    • When the Dedicated Hot Spare is registered for the expansion target RAID group, use the drive smaller than the Dedicated Hot Spare capacity.

    • Select the same sector format of drive (AF-compliant/non-AF-compliant) as the drives that are used to configure the expansion target RAID group.

    • When "RAID1+0" is selected for the RAID level after an expansion, allocate the drives (mirroring pair drives) by dividing them into two or more connection lines (for the ETERNUS DX500 S5/DX600 S5/DX900 S5 and the ETERNUS AF650 S3).

    • When "RAID5" or "RAID6" is selected for the RAID level after an expansion, allocate the drives (multiple drives configuring a striping) by dividing them into two or more connection lines (for the ETERNUS DX500 S5/DX600 S5/DX900 S5 and the ETERNUS AF650 S3).

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

[Tabular] Tab

Click the [Tabular] tab to select drives from the list. The drives that are being used in the selected RAID group and the unused drives that can be used for expansion are displayed on the list.

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

Item Description

Checkbox to select drives

The checkbox for the drive being used in the selected RAID group is selected.

Select the checkbox for the drive that is to be used after expansion.

Clear the checkbox for the drive that is not used after expansion.

When selecting drives, refer to "Requirements for selecting drives".

Enclosure

The enclosure where the drive is installed is displayed.

   CE: Controller Enclosure (2.5" and 3.5")

   DE: Drive Enclosure (2.5", 3.5", and 3.5" high density DEs)

CE#x

DE#yy

x: CE number

yy: DE number

Slot No.

The slot number of the enclosure where the drive is installed is displayed.

2.5" CE/DE: 0 - 23

3.5" CE/DE: 0 - 11

3.5" high density DE: 0 - 59

Drive Type

The drive type displayed for this item is a combination of the following.

  • Drive size

    • For 2.5-inch drives: 2.5"

    • For 3.5-inch drives: 3.5"

  • Drive type

    • For SAS disks: Online

    • For Nearline SAS disks: Nearline

    • For SSDs, the following items are displayed depending on the SSD type.

      • For SSD-Hs (12 Gbit/s): SSD-H (*1)

      • For SSD-Ms (12 Gbit/s): SSD-M (*1)

      • For SSD-Ls (12 Gbit/s): SSD-L (*1)

Note that "SED" is also displayed for self encrypting drives and "AF" is also displayed for Advanced Format compliant drives.

*1  :  The displayed item varies depending on the interface speed (bandwidth) or the capacity of the reserved space. Unless otherwise specified, "SSD-H", "SSD-M", and "SSD-L" are collectively referred to as "SSD". In addition, there may be cases when "SSD SED" is used as the collective term for self encrypting SSD-Hs, SSD-Ms, and SSD-Ls.

Capacity

The capacity of the drive is displayed.

Caution

  • The displayed drive capacity may differ from the product's actual capacity. For example, the drive capacity of a "1.92 TB SSD" is displayed as "2.00 TB" and the capacity of an "18 TB Nearline SAS disk" is displayed as "17.9 TB".

Speed

The drive speed is displayed.

For SSD or SSD SED, a "-" (hyphen) is displayed.

15000 rpm

10000 rpm

7200 rpm

RAID Group

For the drive being used, the RAID group number and the RAID group name are displayed.

For the unused drive, a "-" (hyphen) is displayed.

[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.

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

Item Description Setting values

DE selection list box

Select the DE group.

Options are displayed in the list box when at least one CE or DE in the DE group is installed in the storage system.

Refer to "DE selection list box" for details on the options and DE groups for each model.

DE#0x

DE#1x

DE#2x

DE#3x

DE#4x

DE#5x

DE#6x

DE#7x

DE#8x

DE#9x

DE#Ax

DE#Bx

DE#Cx

DE#Dx

DE#Ex

DE#Fx

DE

Only the CEs or the DEs in the selected DE group that are installed in the storage system are displayed.

CE#x

DE#yy

x: CE number

yy: DE number

Checkbox to select drives

The checkbox for the drive being used in the selected RAID group is selected.

Select the checkbox for the drive that is to be used after expansion.

Clear the checkbox for the drive that is not used after expansion.

For 2.5" CEs or 2.5" DEs, drives are displayed from left to right in ascending order of the slot number. For 3.5" CEs, 3.5" DEs, or 3.5" high density DEs, drives are displayed from bottom left to top right in ascending order of the slot number.

Placing the mouse pointer on the icon displays the detailed information of the drive.

When selecting drives, refer to "Requirements for selecting drives".

Conditions for the ETERNUS DX8900 S4 Drive Layout

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

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

RAID level after changing Drive layout conditions
RAID1+0 Required Allocate mirroring pair drives to different DEs.
Recommended

Allocate striping drives to DEs under as many CEs as possible.

Allocate striping drives to as many SAS cascades (*1) as possible.
RAID5 Required Allocate member drives to different DEs.
Recommended

Distribute member drives to DEs under as many CEs as possible.

Distribute member drives to as many SAS cascades (*1) as possible.
RAID6 Required Allocate two or less member drives to the same DE.
Recommended

Distribute member drives to DEs under as many CEs as possible.

Distribute member drives to as many SAS cascades (*1) as possible.
*1  :  "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.
Caution
  • The requirements for selecting drives to change the RAID level are listed below.
    • When the RAID level before and after LDE is not changed:

      • The drives that are used in the RAID group before LDE was performed cannot be deleted.

    • When the RAID level is changed after LDE:
      • The number of RAID group data drives (*1) after LDE cannot be less than the number before LDE.
        *1  :  "Number of data drives" indicates the number of logical drives in RAID groups that contain user data. This number is different for each RAID level, as shown below.
        RAID Level Drive configuration (*2) Number of data drives
        RAID1+0 nD + nM n
        RAID5 nD + 1P n
        RAID6 nD + 2P n
        RAID1 1D + 1M 1
        RAID0 nD n
        *2  :  D: Data drives, M: Mirror drives, P: Parity drives

      • Drives that are not used after changing the RAID level can be deleted from the RAID group. However, not all of the drives can be deleted from a RAID group.

Operating Procedures

  1. Select the RAID group that is to be expanded and click [Expand] in [Action].

    Caution
    • [Expand] cannot be clicked when the following RAID group is selected.

      • The RAID level is "RAID5+0" or "RAID6-FR".

      • The usage is "Extreme Cache Pool"

      • WSVs are registered

      • The stripe size is not "64KB"

  2. Select the RAID level after expansion and the drives that are to be used after expansion. Click the [Expand] button.

    → A confirmation screen appears.

    Caution
    • An error screen appears in the following conditions:

  3. Click the [OK] button.

    → RAID group expansion starts.

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