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# Non-Disruptive Migration (NDM) warning messages and failure cases

Non-Disruptive Migration (NDM) provides a method for migrating data from a source array to a target array without application host downtime.

There are instances where NDM could succeed, but the resulting masking containers may not follow best practices, host visibility may have unexpected results, or user intervention may be required. In these cases, a warning message is displayed next to the pertinent container name on page 2 of the wizard (Target Masking Options). The following table lists the warnings that are displayed.

Table 1. NDM Warning Messages
Message | Detailed Explanation | Container Impacted | Severity icon
--- | --- | --- | ---
Not all initiators in initiator group have active paths to ports in port group | All initiators in the IG have entries in the Login History table (LHT), so NDM validate succeeded. However, not all initiators in the IG have visibility to ports on the target array. | IG |
Not all ports are online | Not all ports in the port group are online. | PG |
Not all ports in port group have active paths to initiators in initiator group | Not all ports in port group have active paths to initiators in initiator group due to zoning or port status. | PG |
No director redundancy | The port or ports that exist (and are online) in the PG are all on the same director. | PG |
No port redundancy | Only one port exists (or is online) in the PG. | PG |
Recommended ports already in use | WLP has recommended ports based on utilization, but was unable to find unique ports because all candidate ports are used in other masking views for this SG. | PG |
No target port group found | Only used if WLP is not active and there is not visibility between at least one initiator in the source IG and one port on the target array. | PG | Not applicable
Different initiators were logged in on source array | All initiators in the IG have entries in the LHT, so NDM validate succeeded. However, one or more initiators on the source have visibility (logged in) to ports on the target, or conversely. | MV |
Zoning required | Initiators in the IG do not have entries in the LHT, so NDM validate failed. Ports recommended by WLP (or the user selects ) for new PG must be zoned to all initiators in IG. | MV |
Partial zoning required | Some initiators in the IG have entries in the LHT, but not all do, so NDM validate fails. Before an NDM create can succeed, the remaining initiator or initiators must be zoned to ports in the port group on the target array. | MV |
No active paths exist. If no paths are made active before cutover, migration will fail. | All initiators in the IG have entries in the LHT, so NDM validate succeeded. However, none of the paths are active, so suitability cannot be provided. NDM fails unless some of the paths are made active (logged in initiators and online ports) before cutover. | MV |

## Failure Cases

After a storage group, target array, and so on are selected on page 1 of the NDM wizard, Solutions Enabler performs the validation. If the validation succeeds, the migration should succeed with no user intervention. If the validation fails, there are some use cases that allow Unisphere to advise the user on zoning or port selection (if WLP is enabled) or allow the user to pre-create or select port groups (if WLP is not enabled).

Solutions Enabler returns only the first failure encountered. A migration request could have multiple failures. To determine the full set of failures, and to determine whether Unisphere can advise around them, Unisphere has to do its own validation on the target array.

If the first error encountered by SE is an error that is listed in the following paragraphs, Unisphere can fail immediately without doing extra validation.

The use cases below are separated into three groups: failures, successes (SE validate succeeds), and zoning required (SE validation failed or Unisphere can advise around the failures).

## Failure Cases (SE validate and Unisphere validation both fail)

The following scenarios may occur:

- Source side validation failure - SE structure returns null. No additional validation is needed from Unisphere. Unisphere stays on page 1 of wizard. An error dialog displays with error message from SE.
- Storage Groups Exist on Target With Same Name - Included for the sake of completeness. These arrays are already filtered out of the target array combo box on page one of the wizard.
- Masking Views Exist on Target With Same Name - If the SE error enum indicates another issue, Unisphere has to query the target array for name conflicts on each masking view name in the SE structure. If there is a conflict, Unisphere fails the operation. Unisphere stays on page 1 of wizard, and displays an error dialog with an error message.
- Initiator Group(S) Exist on Target, but Have Different Initiators - If the SE error enum indicates something else, Unisphere has to query the target array for each initiator group in the SE structure and ensure that the initiators inside match the initiators on the source. If an initiator group has different initiators on the target, Unisphere fails the operation. Unisphere stays on page 1 of wizard, and displays an error dialog with an error message.
- Initiator Groups do not Exist on Target, but cannot be created - If the SE error enum indicates something else, Unisphere has to query the target array for each initiator group in the SE structure that does not exist on the target and query the target for initiator membership in other IGs on the target. If an initiator exists in another IG on the target, SE is not able to create the IG with the same initiators, so Unisphere fails the operation. Unisphere stays on page 1 of wizard, and displays an error dialog with an error message.
- Same Initiator, Port Path Exists in Multiple Masking Views - If the SE error enum indicates something else, Unisphere has to find port to initiator mappings for each device in the request. No device can have the same initiator to port mapping in multiple masking views. Unisphere stays on page 1 of wizard, and displays an error dialog with an error message.
- Effective Port Flag Validation Fails - If the first SE error indicates this condition, Unisphere can fail and displays an appropriate error message. Unisphere stays on page 1 of wizard, and displays an error dialog with an error message. If the condition exists, but another failure also exists, Unisphere attempts to work around that other issue in zoning advisor mode. When the user runs the NDM create, the full SE validation during create fails.

## Solutions Enabler Validate Succeeds

If validation succeeds:

- SE has determined that every initiator in an IG has at least one LHT entry to a port in the port group for every masking view.
- If the initiator group with the same name exists on the target, SE uses it, otherwise SE creates the IG with the same initiators as the source IG.
- If the port group with the same name exists on the target, SE uses it, otherwise SE creates the port group with all the ports that have LHT entries to the initiators in the IG.

For display purposes, all entries in the LHT are considered. Ports that are not online or not zoned to initiators in IG are colored gray, otherwise they are colored black. Initiators that are not logged in are colored gray, otherwise they are colored black.

For suitability, Unisphere only consider active paths (initiators are logged in, ports are online).

If the port group does not exist on the target, you are allowed to modify the port list before continuing. If selected ports are not already zoned, a "zoning required" warning may be displayed.

The following scenarios may occur:

At Least One Active Path Exists - Port group section shows all ports in the port group. Ports that are online and have host visibility to an initiator in the IG are colored black. Ports that are offline or have no visibility to an initiator in the IG are colored gray. Initiator group section shows all initiators in the initiator group. Initiators that are logged in on one or more ports in PG are colored black. Ports that are not logged in are colored gray. Suitability (If WLP Enabled) is tested by adding load to all ports or directors that have current paths (online ports or logged in initiators) to initiators in IG.

No Active Paths Exist - SE validate succeeds if all initiators have LHT entries. However, if there is not at least one active path, suitability is not available and NDM cutover fails. The Run Now button is disabled in this case, only Add to Job List is enabled since user intervention is required. The port group section shows all ports in the port group. All ports are colored gray. There is no PG level warning icon. Initiator group section shows all initiators in the initiator group. All initiators are colored gray. There is no IG level warning icon. No active path warning icon is displayed at the masking view level. Suitability (If WLP Enabled) cannot be tested. Suitability component is not shown. A warning is shown next to problematic masking view.

## SE Validate Fails and Unisphere Validation Succeeds - Zoning Required

If SE validation fails and Unisphere validation succeeds, then Unisphere goes to zoning advisor mode (if WLP is available) or allows user port selection (regardless of WLP availability).

The following scenarios may occur:

PG Name Already Exists on the target -The contents of the IG must be the same on the source and target, so it does not matter if the IG exists or not. If the IG exists, the IG is reused. If the IG does not exist, the IG is created. The Initiator group section displays all initiators in the initiator group on the source side. When zoning is required, assume that all initiators in IG have visibility to ports in PG, so all initiators are colored black. The Port group section shows all ports in the port group. If ports are online, they are colored black, otherwise they are colored gray. A zoning required warning is displayed. For Suitability (If WLP Enabled), the load is applied evenly to all online ports in port group for suitability.

No PG, no IG, no zoning - The Initiator group section displays all initiators in the initiator group on the source side. When zoning is required, no initiators in IG have visibility to ports in PG, so all initiators are colored gray. There is no IG level warning icon. If WLP is enabled, the WLP-selected ports are displayed in the port group section. All ports are colored gray. There is no PG level warning icon. If WLP is disabled, a port add icon is shown with an appropriate message. Zoning required warning is shown at the masking view level. For Suitability (If WLP Enabled), the load is spread evenly across WLP-selected ports.

LHT Entry Exists for Some Initiators in IG, But Not All - The Initiator group section shows all initiators in the initiator group on the source side. An initiator with no LHT entry on the target array is shown in the color gray, otherwise is shown in the color black. All ports visible to initiators on the target side are shown in port group. Zoning required warning is shown. For Suitability (If WLP Enabled), Suitability uses ports visible to WWNs that are logged in.