Create REC Disk Buffer

Overview

This function creates an REC Disk Buffer.

When using the REC Consistency mode, REC Buffer shortage may occur due to errors (such as an unstable line). Note that the copy session will be in the "Halt" state if the REC Buffer shortage extends for a certain period of time. The REC Disk Buffer is used for temporarily saving copy data to avoid these situations.

Caution

  • Registering the license for the Advanced Copy function is required to create an REC Disk Buffer.

  • This function can only be used when the local storage system (the storage system that creates REC Disk Buffers) supports REC.

  • When the encryption mode is disabled, an REC Disk Buffer encrypted by CM cannot be created.

  • In the following conditions, REC Disk Buffers cannot be created:

    • When multiple types of drives are combined in a single REC Disk Buffer

      Refer to the "Drive Combinations That Can Configure an REC Disk Buffer" for details.

    • When resources for creating an REC Disk Buffer (such as the number of RAID groups and volumes) are insufficient

      (When the maximum number of RAID groups or volumes already exists in the storage system, REC Disk Buffers cannot be created.)

Note

  • When the REC Disk Buffer creation process has been completed, the REC Disk Buffer is formatted automatically.

  • When assigning multiple REC Disk Buffers to an REC Buffer, each REC Buffer has different conditions. Refer to the [Assign REC Disk Buffer] function for details.

Drive Combinations That Can Configure an REC Disk Buffer

  Online Nearline SSD Online SED Nearline SED SSD SED
Online OK OK (but not recommended) NG NG NG NG
Nearline OK (but not recommended) OK NG NG NG NG
SSD NG NG OK NG NG NG
Online SED NG NG NG OK OK (but not recommended) NG
Nearline SED NG NG NG OK (but not recommended) OK NG
SSD SED NG NG NG NG NG OK

OK: REC Disk Buffers can be created    OK (but not recommended): REC Disk Buffers can be created, but not a recommended configuration    NG: REC Disk Buffers cannot be created

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.

Settings

This function creates a new RAID group to be used as an REC Disk Buffer.

New RAID Group

Item Description Setting values

Name

Input a RAID group name to be created.

An existing RAID group name cannot be used.

Up to 16 alphanumeric characters,

symbols (except "," (comma), "?", and "%" (used as the first character)),

and spaces

Manual Setting

Select the drives configuring the REC Disk Buffer.

Item Description Setting values

Controlling CM

Specify the Controlling CM of the RAID group to be created.

"Automatic" and the normal CM number ("CE#x CM#y" or "CM#y") that is installed are displayed as options.

Select "Automatic" for normal operations. When "Automatic" is selected, the Controlling CM that is to be allocated is determined by the RAID group number. Refer to "Automatic Controlling CM Setting" for details.

For the ETERNUS DX900 S5 or the ETERNUS DX8900 S4

Automatic

CE#x CM#y

For the other models

Automatic

CM#y

x: CE number

y: CM number

RAID Group Capacity

The RAID group capacity is displayed.

If RAID groups cannot be configured with the selected drives, a "-" (hyphen) is displayed.

Encryption by CM

Select the RAID group encryption status with the radio button.

If RAID groups cannot be configured with the selected drives, a "-" (hyphen) is displayed.

  • To use a CM to perform encryption, select "On".

  • To perform encryption without using a CM, select "Off".

When the encryption mode is disabled, "On" cannot be selected.

When "On" is specified for "Encryption by CM", select Online, Nearline, or SSD type drives.

On

Off

Advanced Setting

Stripe Depth should be set only when advanced tuning needs to be performed for each RAID group configuring the REC Disk Buffer.

Item Description Setting values

Stripe Depth

Select the Stripe Depth of the RAID group that is to be created. It is not necessary to change the default value (64KB) for normal use.

The Stripe Depth of the RAID groups configuring the REC Disk Buffer, which has already been created, cannot be changed.

When two drives are selected, Stripe Depth is 64 KB.

Note

  • Specifying a large value for Stripe Depth may enhance the random access performance to the corresponding RAID group.

64 KB (Default)

128 KB

256 KB

512 KB

1024 KB

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 conditions of the RAID group to be used as an REC Disk Buffer are shown below.

    • The number of member drives is two, four, or eight

      (The RAID level for the REC Disk Buffer is RAID1, RAID1+0(2+2), or RAID1+0(4+4).)

    • Do not combine different drive types (Online/Nearline/SSD/Online SED/Nearline SED/SSD SED)

      (Although "Online" type drives and "Nearline" type drives can be used in the same REC Disk Buffer, 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 REC Disk Buffer, 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 REC Disk Buffer.)

    • The drive size must be smaller than 6 TB (except SSDs and SSD SEDs)

  • The recommended drive configuration of the RAID group is shown as follows:

    • Select drives with the same capacity. If drives of different capacities exist in a RAID group, the smallest becomes the standard, and all other drives are regarded as the same capacity as the smallest drive. In this case, the remaining drive space is not used.

    • Select drives with the same speed. If drives of different speeds exist in a RAID group, access performance of the RAID group may be affected.

    • Select the same SSD type (SSD-H/SSD-M/SSD-L/SSD-H SED/SSD-M SED/SSD-L SED).

    • If the host connection environment does not support Advanced Format (AF), select non-AF-compliant drives (*1). If AF-compliant drives (*2) are selected, a data format conversion occurs and the drive access performance is reduced. When the host to be connected supports AF, both AF-compliant and non-AF-compliant drives can be selected.

      *1  :  Drives (such as 2.5" Online and 2.5" Nearline) where "AF" is not displayed for the type.
      *2  :  Drives (such as 2.5" Online AF and 2.5" Nearline AF) where "AF" is displayed for the type.

  • 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. Only unused drives 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.

Item Description

Checkbox to select drives

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

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

[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 DX8900 S4 drive layout. Refer to "Conditions for the ETERNUS DX8900 S4 Drive Layout" for details.

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

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

CE

CE#x

DE#yy

x: CE number

yy: DE number

Checkbox to select drives

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

Checkboxes are displayed for unused drives. 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 must satisfy the conditions described below.

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

RAID level 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.
RAID1 Required Allocate mirroring pair drives to different DEs.
Recommended

Allocate pair drives under different CEs as possible.

Allocate pair drives under different 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.

Operating Procedures

  1. Click [Create REC Disk Buffer] in [Action].

  2. Specify the REC Disk Buffer detailed information, and click the [Create] button.

    → A confirmation screen appears.

    Caution
    • An error screen appears in the following conditions:

      • The "Name" is not entered

      • The RAID group name specified in the "Name" field does not satisfy the input conditions

      • The selected drives do not satisfy the input conditions

      • The selected drives do not satisfy the required layout conditions

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

  3. Click the [OK] button.

    → Creation of an REC Disk Buffer starts.

  4. Click the [Done] button to return to the [REC Disk Buffer] screen.