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7MTT Copy-Based Transition - Consolidation of volumes from multiple 7-Mode storage systems or vFiler units into a single SVM using the v2.0 or later versions of the tool

Applies to

  • Clustered Data ONTAP 8, 7-Mode
  • Transition Tool

Answer

Objective:

The objective of this article is to provide considerations and recommendations for advanced users or Professional Service Engineers who might want to consolidate volumes from multiple 7-Mode storage systems or vFiler units into a single SVM using the 7-Mode Transition Tool v2.0 or later versions of the tool and is only applicable for Copy-Based Transition.

From v2.2 version of the tool, 7MTT also supports Copy-Free Transition along with the exising Copy-Based Transition. But this article is applicable only for Copy-Based Transition.

Regardless of the migration method, consolidation of the volumes from multiple 7- Mode storage systems or vFiler units to a single SVM should be done after analysis of the configurations for the involved storage systems, finding and resolving conflicting configurations.

For example, volumes with identical names cannot be transitioned into the same SVM, unless the target volumes are created with non-conflicting names during the transition; two different Active Directory Domains cannot be configured on the same SVM.

7-Mode Transition Tool does not detect the configuration conflicts specific to consolidation case in the preparation phase (pre-checks). However, it might detect some of the issues later in the transition process (during ‘start’ operation or in the pre-cutover and cutover phase). Therefore, users planning to consolidate volumes from multiple 7-Mode storage systems or vFiler units to a single SVM are strongly encouraged to analyze configurations of the involved 7-Mode storage systems. Some of the considerations and recommendations are described below.

Considerations while preparing transition projects:

There are certain scenarios where the consolidation must not be attempted. If attempted, the 7-Mode Transition Tool blocks the user from proceeding with the transition, either during the pre-check phase or during the cutover phase.

Enabling parallel consolidation:

In the normal workflow, the 7-Mode Transition Tool restricts parallel consolidation of multiple 7-Mode storage systems or vFiler units to a single SVM. This means that the consolidation can only be done in a sequential manner. For example, if there are two projects that are attempting consolidation, the first project must be completed (from
preparation to the cutover operation) first, and only then the second project can be prepared.

This limitation is to make sure that the cutover operation is not blocked because of conflicting configurations, as discussed earlier. This will also make sure that all the conflicting configurations are detected during the pre-check phase itself and possible corrective actions can be taken before proceeding with the transition.

However, for advanced users or Professional Service Engineers who would like to attempt parallel consolidation, the 7-Mode Transition Tool provides a hidden option.

When this hidden option is enabled, the tool will allow parallel consolidation. Users must be careful while this option is enabled and must ensure that they do not attempt to consolidate the configurations that will result in blocking the cutover operation. Refer to the section 'Scenarios not supported for consolidation of volumes: 'for more details about such configurations.'

To enable parallel consolidation, add the following line to the end of the
$TOOL_INSTAL_DIR\etc\conf\transition-tool.conf file:

allow.vserver.parallel.consolidation = true

After adding the hidden flag, restart the Windows service 'NetApp 7-Mode Transition Tool' for this flag to take effect.

Perform the following steps to stop and restart the 7-Mode Transition Tool service:

  1. On the Windows system where the 7-Mode Transition Tool is installed, click Start > Control Panel > System and Services > Administrative Tools > Services.
  2. Right-click the ‘NetApp 7-Mode Transition Tool’ service and click Stop.
  3. Once the service is stopped, right-click the service and click Start to start the service again.

Scenarios not supported for consolidation of volumes:

1. CIFS Active Directory

7-Mode storage systems or vFiler units with CIFS server are bound to different Active Directory domains. This is not supported because CIFS server configured on the target SVM can be bound to exactly one Active Directory domain. If such a consolidation is attempted, the 7-Mode Transition Tool will block the transition either during the preparation phase (pre-checks) or during the cutover phase.

2. CIFS Local Users and Groups

Transition of 7-Mode local users and groups from different 7-Mode systems: 7-Mode Transition Tool will transition the 7-Mode local users and groups to the target SVM only if at least one 7-Mode volume selected for the transition has one or more CIFS shares or home-directory paths configured. During local users and groups transition, the target SVM will always get one or more non-BUILTIN users from the 7-Mode storage system (this occurs because the 7-Mode storage systems will always have few non-BUILTIN local users and groups, and this is the case even in default 7-Mode setup). The transition is blocked if the target SVM already has any local users and groups other than BUILTIN local users and groups.

If the SVM has only BUILTIN local users and groups, the first local users and groups transition will succeed and the subsequent projects targeting the SVM will be blocked because some non-BUILTIN local users and groups were already transitioned to the SVM in the first project. You can overcome this limitation by deleting all thenon-BUILTIN local users and groups on the target SVM  before starting each subsequent project. However, if you need to retain the local users and groups transitioned in the last project, you must transition the volumes in the subsequent projects to different SVMs.

Note: Attempting multiple transitions from a given 7-Mode storage system or vFilerunit to a given SVM is supported. The first transition project will carry local users and
groups to the target SVM and subsequent transitions will ignore the local users and groups transition.

3. Different NIS Configuration

Consolidation of 7-Mode storage systems or vFiler units with different NIS configuration (NIS domain, NIS servers) is not supported and will be blocked by the7-Mode Transition Tool.

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General considerations while consolidating:

There are scenarios where the consolidation can be attempted, however, you must be aware of certain limitations and must plan to perform some manual tasks after the
transition is complete. Most of these limitations come into picture if there are conflicting configurations present on the 7-Mode source systems that are part of the consolidation.

  • Ensure that the number of LIFs created on each cluster node does not exceed the limit (256). 7-Mode Transition Tool creates the LIFs during the cutover phase.
  • The NFS options on the target SVM will be overwritten with the values from the source 7-Mode storage system. Once the consolidation is completed, carefully examine the option values and modify them appropriately. Some of the important 7-Mode options to look out for are  ‘nfs.v3.enable’ and ‘nfs.v4.enable’.

    For example, if ‘ nfs.v3.enable ’ is set to ‘off’ on the 7-Mode storage system, NFSv3 will be disabled on the target SVM during transition. This might not be the desired behavior if the target SVM is already serving the NFSv3 clients.
     
  • If the 7-Mode sources attempting consolidation have CIFS shares with same names, the shares from the 7-Mode source for which the cutover is attempted first will be transitioned. Subsequent transitions from other 7-Mode sources will fail to create those shares and their ACLs. Such shares must be configured with a different name after the consolidation and the ACLs must be applied manually. The same behavior applies to CIFS name-mapping configurations.
  • It is not recommended to consolidate 7-Mode source volumes that have CIFS home-directory paths in such a way that two 7-Mode source volumes have home directories serving users with same names. If consolidation is attempted in such cases, after the transition, those users will end up having two home directories on the cluster and might be redirected to any home directory at random.
  • If the 7-Mode storage systems attempting for consolidation have entries with same host names, but are mapping different IP addresses in their ‘/etc/hosts’ file, the project for which cutover is attempted first will transition the hosts configuration. The subsequent project cutovers will fail to apply those hosts. Same behavior is applicable for the ‘/etc/passwd’ and the ‘/etc/groups’ configuration of the 7-Mode sources.
  • If transition is attempted from 7-Mode sources for which the order of name services for a particular database is different, the order of name services of the 7-Mode source for which the cutover is attempted first is retained and will not be modified during subsequent transitions. After the consolidation is completed, carefully review the SVM name services order and modify them, if required.
  • If the 7-Mode sources attempted for the consolidation have different LDAP configurations, the LDAP configuration from the 7-Mode source for which the cutover is attempted first will be transitioned, and the subsequent transitions from other 7-Mode sources will ignore LDAP configuration transition.

Considerations for the start operation:

  • For the consolidation, it is recommended to manually create the target SVM prior to the transition.
  • Make sure that clustered Data ONTAP volume names do not conflict across the projects that are attempting the consolidation. The 7-Mode Transition Tool does not detect the conflicting configurations between its projects. If there are conflicting clustered Data ONTAP volume names across the projects, the tool will create volumes on the target SVM during the ‘start’ operation of the first project and it will detect the volume name conflicts during the ‘start’ operation of the second project; as a result of which the ‘start’ operation on the second project will fail. If it happens, user will need to modify the second project (change conflicting volume names), rerun, and then ‘start’ the operation.
  • Ensure that sufficient space is available on the cluster aggregates to create clustered Data ONTAP volumes during the start operations across multiple projects.
  • Ensure that the node and the SVM volume limits are not reached because of the consolidation. If this happens, creation of the clustered Data ONTAP volumes fails with appropriate errors.

SAN Consolidation:

  • Cluster Failover Mode (cfmode) is an FC setting that determines the behavior of FC target ports, particularly during a cluster failover event. Single System Image cfmode (SSI) presents the HA configuration as a single target. This enables all LUNs to be visible from all controller ports.
  • Use the fcp show cfmode command to determine the cfmode settings on the 7-Mode system. The possible values for this option are single_image and unknown. When the controllers are set to operate as an HA-pair, they are in the SSI mode.

Transitioning Volumes with LUNs from a Data ONTAP 7-Mode HA system in SSI:

Recommended steps to perform a SAN transition from Data ONTAP 7-Mode HA partners to clustered Data ONTAP using the 7-Mode Transition Tool:

  1. Create two transition projects using the 7-Mode Transition Tool. Configure the projects with the same target Storage Virtual Machine (SVM). Each project must contain all the volumes that have LUNs mapped for FC access from each node.
  2. Use the hidden option allow. vserver. parallel. consolidation to enable creation of projects targeting the same SVM.
  3. Perform Pre-check, Start, and Pre-cutover operations on the two projects simultaneously.
  4. Perform the cutover of the two projects back to back in the same cutover window. This will enable the hosts to discover all the transitioned LUNs from the SVM after transition is complete.
  5. Post transition, igroup conflicts can occur if a pre-existing igroup on the destination SVM has the same name as the igroup being transitioned. If igroup conflicts are reported by the tool, follow the corrective action suggested by the tool to cleanup any igroup conflicts.

Note 1: If a host is being served by LUNs from both the nodes of the HA system, then it is mandatory to follow the above procedure for consolidation. On the other hand, if the host is not being served by LUNs from both the nodes of the HA system, it is not mandatory to follow the above procedure. In the latter case, the transition projects can be targeted to two different SVMs.

Note 2: If the procedure listed above is not followed, post transition complications will arise in zoning, multipathing, and host remediation. Additionally, if consolidation is not performed, there will be higher management and operational costs, because two or more SVMs will have to be maintained in order to serve data.

Transitioning Volumes with LUNs from a Data ONTAP 7-Mode HA system that is NOT in SSI:

Recommended steps to perform a SAN transition from two Data ONTAP 7-Mode non-HA partners:

  1. Create two or more transition projects using the 7-Mode Transition Tool and configure the projects with a different target Storage Virtual Machine (SVM).
  2. Perform Pre-check, Start, and Pre-cutover operation on the two projects.
  3. Perform Cutover in the same or in different maintenance windows, as required.

Additional Information

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