Creating Thin Image pairs using Device Manager

Creating Thin Image pairs using Device Manager - Storage Navigator

Thin Image User Guide

Version

9.8.6

Audience

anonymous

Part Number

MK-98RD9020-16

You can create a Thin Image pair and define the pair in a consistency group (CTG). You can create 1,024 Thin Image pairs at the same time for VSP 5000 series and 32,768 for VSP E series. To create more than 1,024 (or 32,768) pairs, repeat this task.

When you create a pair, you specify the pool to be used. A Thin Image pair consists of a P-VOL and up to 1,024 S-VOLs. The MU numbers are assigned in the order of 3 to 1,023, followed by 0 to 2. If you use the CCI raidcom add snapshot command to create a pair, you can specify the MU number. If you use CCI commands, see Pair tasks using CCI or Device Manager - Storage Navigator.

CAUTION:

If the host server is down or has failed, a CTG that contains no Thin Image pairs might be created. Under such conditions, if you are using CCI to create a pair for CTG pair-split by running the paircreate command, the command might be rejected. In this case, look for a CTG in which an error occurred on the Consistency Groups tab in the Local Replication window, and then intentionally create a pair in the specified CTG.

Additionally, if the host server is down or has failed, many CTGs that contain no Thin Image pairs might be created and there might not be enough available CTGs. In this case, look for a CTG that contains no Thin Image pairs on the Consistency Groups tab in the Local Replication window, and then intentionally create a pair in the specified CTG. After that, delete the pair, thereby also deleting the CTG that contains no Thin Image pairs.

Requirements:

If you create a Thin Image pair with S-VOLs specified, the P-VOL and S-VOLs you select must be the same size in blocks. If the capacity is displayed in GB or TB, a small difference between P-VOL and S-VOL capacity might not be displayed. To view the capacity in blocks, click Options > Capacity Unit > block in the Logical Devices window.
If you select a P-VOL that is already being used as the P-VOL for another Thin Image pair, you must specify the same pool for both pairs. For example, if you specify three S-VOLs for one P-VOL, specify the same pool for the three Thin Image pairs.
The value of the T10 PI attribute must be the same for the P-VOL and S-VOL.
A Thin Image pair cannot be created when the used pool capacity exceeds the warning threshold. In this case, increase the pool capacity first, and then create the pair.
To prevent the Thin Image pairs from being suspended ("PSUE" status), do not create Thin Image pairs while you are shutting down the storage system.
When only the P-VOL capacity of a Thin Image pair has been expanded, a cascaded pair cannot be created. Create the cascaded pair after expanding all of the volume capacity used in the pairs.

You must have the Storage Administrator (Local Copy) role.
If you are sharing ShadowImage volumes with Thin Image volumes, the SI pair must already exist.
If you want to use a ShadowImage S-VOL as a Thin Image P-VOL when an available MU number does not exist, you must complete the following before creating the pair:
1. Delete the Thin Image pairs of MU numbers 0 to 2.
2. Create the ShadowImage pair.
3. Re-create the Thin Image pair with an MU number of 3 or greater assigned.

In the Explorer pane, click Storage Systems.
Expand the storage system tree, expand Replication, and then click Local Replication.
In the Local Replication window, select a P-VOL on the TI Root Volumes tab or a snapshot group in the Snapshot Groups tab, and then click Create TI Pairs.
In Create Pairs using Volumes as Root Volumes or Use Primary Volumes of Thin Image Pairs, select Yes or No.
In Select By, select LUN to create a pair by specifying LUN. Select LDEV to create a pair without specifying LUN.
From the Available Primary Volumes table, select the LDEV you want to assign as the P-VOL.

Note: The nondisruptive migration volumes do not appear in the Available Primary Volumes table.
In Cascade, select Enable to create a cascaded pair.
In Pair Type, select Snapshot to create a pair with the snapshot attribute. Select Clone to create cloned pairs. Skip to step 11 if you selected No for Create Pairs using Volumes as Root Volumes.
Click Select Pool.
In the Select Pool window, select a pool from the Available Pools table.
Click OK.
For Snapshot Group, select either Create New to assign the pair to a new snapshot group, or Use Existing to assign the pair to an existing snapshot group. When you create a Thin Image pair, you must assign it to a snapshot group.
Complete one of the following:
- For Create New, enter values for Number of Snapshot Data per Primary Volume, Prefix, and Initial Number, and then select Snapshot Group Configuration.
  When you specify an initial number that was already registered, the smallest available number that is the same as or larger than the specified number is automatically set.
- For Use Existing, select Snapshot Group Configuration, and then select the snapshot group to which you want to assign the pair from the Available Snapshot Groups table.
  If you select All, enter a value in Number of Snapshot Data per Primary Volume.
Note: To create pairs and assign the pairs to a snapshot group by using CCI, see Adding Thin Image pairs to snapshot or consistency groups using CCI.
Click Add.
The selected LDEV is moved to the Selected Primary Volumes table.
Click Next.
From the Available LDEVs table, select the LDEV you want to assign as the S-VOL, and then click Set.
The selected LDEV is displayed in the Secondary Volumes column of the Selected Pairs table.
Note:
- The nondisruptive migration volumes do not appear in the Available Primary Volumes table.
- If you select a capacity in Capacity, the Available LDEVs and Selected Pairs tables display the LDEVs that match the selected capacity.
- If you select a row in the Available LDEVs table and a row in the Selected Pairs table, and then click Set, you can configure a pair.
- If you select LDEVs which were assigned to an S-VOL with the Exclude Assigned Volumes check box unchecked, you can change the S-VOL to which snapshot data is assigned.
Click Finish, and then confirm the settings.
Accept the default task name or enter a unique name.
You can enter up to 32 letters, numbers, and symbols, except the following:
\ / : , ; * ? " < > |
If you want to monitor the task after submitting it, select Go to tasks window for status.
Click Apply to submit the task.

Note: After creating a Thin Image pair, the number of pairs shown in the summary section in the Local Replication window and the number of pairs shown in the list in the TI Pairs tab might be different. Wait until the configuration information has completed processing. If the numbers of pairs still do not match, reload the configuration information (see Reloading Thin Image configuration information).