Hitachi Storage Navigator Modular 2 User Guide

							Managing RAID Groups8–3
Hitachi Storage Navigator Modular 2 User’s Guide
Figure 8-1:  Example of RAID Groups Tab
Table 8-1 summarizes the RAID Group activities described in this chapter.
Creating a RAID group
RAID groups can contain single or multiple parity groups. A RAID group can 
be considered as the actual RAID container for data protection, and the 
parity group as a partition of that container. This way, multiple LUNs can be 
created from each RAID group, and ported out to the same or different 
servers. This allows granularity in LUN sizes being obtained from the RAID 
group.
You can create a RAID group by combining only drives of the same drive 
type. 
Table 8-1:  RAID Group Tasks
TaskSee Page
Create RAID groups 8-3
Expand RAID groups 8-5
Remove expansion from RAID groups 8-9
View detailed properties about the RAID groups you have defined 8-10
Execute a RAID group spin-up or spin-down 8-13
Change RAID group expansion priority 8-14
Filter the RAID groups shown in the RAID Groups tab 8-15
Delete RAID groups 8-16 
						

							8–4Managing RAID Groups
Hitachi Storage Navigator Modular 2 User’s Guide
This procedure is intended for maintenance technicians or qualified users. 
Contact Hitachi Data Systems customer support if you have any questions 
regarding this feature.
To create a RAID group
1. In the RAID Groups tab of the Logical Units window, click Create RG. 
The Create RAID Groups window appears (see Figure 8-2).
Figure 8-2:  Example of Create RAID Groups Window
2. Complete the fields in the window (see Table 8-2).
3. Set the drive to either Automatic Selection or Manual Selection.
4. Click OK to save the settings.
5. When a message states that the operation was successful, click Close 
to close the window and return to the RAID Groups window.
Table 8-2:  Fields in the Create RAID Groups Window
FieldDescription
RAID Group Name of the displayed RAID group.
RAID Level Number of the RAID level (1-6) that has 
been assigned to the RAID group.
Combination RAID combination assigned to the RAID 
group.
Number of Parity Groups Number of parity groups assigned to the 
RAID group. 
						

							Managing RAID Groups8–5
Hitachi Storage Navigator Modular 2 User’s Guide
Expanding RAID groups
You can expand the capacity of the RAID group for AMS storage systems 
without interrupting host I/O by adding a drive to the specified RAID group. 
Data is reallocated as a background process and can require some time to 
complete. 
RAID groups can be expanded with the following restrictions: 
• Only one RAID group can be expanded per command from Navigator 2, 
but you can execute the command multiple times, which allows you to 
expand more than one RAID group per Navigator 2 session. 
• The RAID group expansion process operates on a maximum of two 
RAID groups at a time. This means that if you issued the expansion 
command to additional RAID groups, those commands are queued and 
the expansion will be executed and other RAID groups have completed 
their expansion process.
The following sections describe guidelines for expanding RAID groups.
General guidelines
You cannot expand a RAID group under the following circumstances:
• If the LU whose status of the forced parity correction is any of the 
following status messages observed in the RAID group of the expansion 
target:
• Correcting
• Waiting
• Waiting Drive Reconstruction
•  Unexecuted, Unexecuted 1, or Unexecuted 2 
If any of the above messages are displayed, you need to execute a 
forced parity correction for this LU, change the LU status to Correction 
Completed, and then execute the RAID group expansion.
• If an LU is being formatted and belongs to the RAID group expansion 
target. Wait until the formatting has completed and then execute the 
expansion command from Navigator 2.
• If the following LU types are in the RAID group of the expansion target: 
•  LUs set for a pair other than PSUS of ShadowImage in-system 
replication.
•  LUs set for a pair other than PAIR of Copy-on-write SnapShot.
•  LUs set for a pair other than PSUS of TrueCopy remote replication.
•  LUs set for a pair other than PSUS of TrueCopy Extended Distance.
Drives Automatically or manually select the drives 
that will be a part of this RAID group.
Table 8-2:  Fields in the Create RAID Groups Window
FieldDescription 
						

							8–6Managing RAID Groups
Hitachi Storage Navigator Modular 2 User’s Guide
•  LUs or reserve LU during Modular Volume Migration.
•  LUs in which Cache Residency Manager is set.
For any of the above conditions, change the LU status and then expand 
the RAID group.
• After setting or changing Cache Partition Manager configuration. The 
storage system must be rebooted. Expand the RAID group after 
rebooting the storage system.
• In which the Power Saving function is set. Change the status of the 
Power Saving feature to “Normal (spin-up)” and then expand the RAID 
group.
• When the dynamic sparing/correction copy/copy back is operating. 
Expand the RAID group after the drive has been restored.
• While installing the firmware. Expand the RAID group after completing 
the firmware installation.
RAID group expansion best practices
Host access performance deteriorates during the RAID group expansion. 
Specifically, the LU in the RAID group which is expanding mostly affected. 
Execute the RAID group expansion at a time when host I/O is at a minimum.
For RAID group expansion, you can specify whether to give priority to the 
host I/O or the RAID group expansion itself.
Perform backups of all data, including data stored in cache memory, before 
executing the expansion. Data loss can occur due to a power or some other 
type of system failure, and the LU associated with the expansion can 
become unformatted.
The RAID group expansion expands the number of data disks of the RAID 
group. You cannot change the RAID level, for example from (4D+1P) to 
(4D+2P). You can expand the RAID group from RAID 1 to RAID 1+ 0. You 
cannot expand a RAID group that has a RAID level 0.
Only RAID groups that have one parity group can be expanded.
You can use the added capacity immediately after the expansion process 
has completed.
The total number of HDD that you can add is 8 per RAID group.
The drive to be added must be of the same drive type (SAS, SATA, or SSD) 
as the RAID group of the expansion target. Moreover, the capacity more 
than or equal to the minimum capacity drive in the RAID group of the 
expansion target is required.
Hitachi strongly recommends that the drive added be of the same capacity 
and rotational speed as the RAID group of the expansion target to maximize 
performance.
When expanding the RAID group of RAID 1 or RAID 1+0, add drives in 
multiples of 2. 
						

							Managing RAID Groups8–7
Hitachi Storage Navigator Modular 2 User’s Guide
Expanding RAID groups
The following procedure describes how to expand RAID group. Expanding a 
RAID group can affect host I/O performance during the expansion.
To expand a RAID group
1. In the left column of the RAID Groups tab of the Logical Units window, 
click the checkbox of the RAID group you want to expand.
2. Click Expand RG. The Expand RAID Group window appears (see 
Figure 8-3).
Figure 8-3:  Example of the Expand RAID Group Window
3. Select a drive to add from the Assignable Drives table. If the number 
of drives exceeds what the table can show, use the controls at the top 
of the table to scroll through other drives. You can also use the Filter 
button to filter out drives that do not meet your criteria.
4. To see the resulting capacity of the expanded RAID group, click Refresh 
Capacity of Expanded RG.
5. Click OK. A warning message appears.
6. In the displayed message box, read the confirmation and warnings, then 
click the check box to the left of the text to agree.
7. Click Confirm to expand the RAID group (or click Cancel to not expand 
it). 
						

							8–8Managing RAID Groups
Hitachi Storage Navigator Modular 2 User’s Guide
8. When a message states that the operation was successful, click Close 
to close the window and return to the RAID Groups tab. 
						

							Managing RAID Groups8–9
Hitachi Storage Navigator Modular 2 User’s Guide
Removing RAID group expansion
To remove RAID group expansion
1. In the left column of the RAID Groups tab of the Logical Units window, 
click the checkbox of the RAID group from which you want to remove 
expansion.
2. Click Remove Expansion. The Expand RAID Group window appears 
(see Figure 8-3).
Figure 8-4:  Example of the Expand RAID Group Window 
						

							8–10Managing RAID Groups
Hitachi Storage Navigator Modular 2 User’s Guide
Displaying detailed RAID group properties
To display the detailed properties of a RAID group assigned to a storage 
system.
To display detailed properties
1. In the RAID Groups tab of the Logical Units window, click a RAID group 
under the RAID Group column. The Properties window for the selected 
RAID group appears (see Figure 8-5).
Figure 8-5:  Example of Detailed RAID Group Properties
2. Review the fields in the Summary section of the window (see Table 8-
3).
Table 8-3:  Fields in the RAID Group Window
ItemDescription
RAID  Group Name of the displayed RAID group. The default name for 
the first group is RG-000.
RAID Level Number of the RAID level (1-6) assigned to the RAID 
group.
Combination Name of the parity group that has been assigned.
Number of Parity Groups Number of parity groups assigned to the RAID group.
Status  Status of expanded RAID group.
Capacity Displays both the total capacity of the hard drive(s) in the 
RAID group and the free space left on the drive(s).
Drive Type Displays the type of drive(s) contained in the RAID 
group: SAS, SATA, or SSD. You cannot mix drive types 
within the same RAID group.
RG Expansion Priority The priority that displayed RG Expansion or Host Access 
when expand RAID group. 
						

							Managing RAID Groups8–11
Hitachi Storage Navigator Modular 2 User’s Guide
In addition to the Summary section described above, the Detailed RAID 
Group Properties contains two tabs:
• Logical Units
• Assigned Drives
The following sections describe each tab.
Understanding the Logical Units tab
The Logical Units tab displays a table with a list of logical units in the 
selected RAID group, with statistics about each LUN. Controls at the top of 
the table let you display the first, next, previous, last, and specific page of 
the Logical Units table. Figure 8-5 on page 8-10 shows an example of this 
tab. Table 8-4 describes these statistics.
Understanding the Assigned Drives tab
The Assigned Drives tab displays a table with a list of the drives in the 
selected RAID group. Figure 8-6 on page 8-12 shows an example of the 
Assigned Drives tab. In this tab, you can click a value in the HDU column 
to view detailed information about the HDU (see Figure 8-7 on page 8-12 
for example).
Table 8-4:  Logical Units Tab Fields
ItemDescription
LUN Displays the name of the logical unit.
Capacity Displays the total size of the LUN in GB.
Stripe Size Displays the size of the data stripe on the HDU (hard 
drive unit) that is assigned to the LUN. 
Cache Partition Displays the number of cache partitions assigned to the 
LUN (range is 0 to nnn)
Pair Cache Partition Displays the number of cache partition pairs assigned to 
the LUN. The range is Auto, 0 - nnn)
Status Shows the status of the LUN. Possible status can be 
None, Quick Formatted (and percentage completed), and 
Uncorrected. 
						

							8–12Managing RAID Groups
Hitachi Storage Navigator Modular 2 User’s Guide
Figure 8-6:  Example of Assigned Drives Tab
Figure 8-7:  Example of HDU Window