- Notes, cautions, and warnings
- Preface
- CLI Workspace and User Accounts
- Meta Volumes
- System Management
- Events and alerts
- About call-home notifications
- Additional documentation
- SupportAssist MFT feature
- Event log locations
- System Configuration log location
- SupportAssist Syslog
- SupportAssist syrcollect feature
- SupportAssist Connectivity Command
- Hardware acceleration with VAAI
- Offload copy overhead with XCOPY
- Change the name of the cluster
- LCD Front Panel settings
- Thin support in metro node
- Provisioning Storage
- Volume expansion
- Data migration
- About data migrations
- Migrating thin-capable storage
- About rebuilds
- One-time data migrations
- Batch migrations
- Prerequisites
- Creating a batch migration plan
- Checking a batch migration plan
- Modifying a batch migration file
- Starting a batch migration
- Pausing/resuming a batch migration (optional)
- Canceling a batch migration (optional)
- Monitoring a batch migration’s progress
- Viewing a batch migration’s status
- Committing a batch migration
- Cleaning a batch migration
- Removing batch migration records
- Configure the WAN Network
- Cluster Witness
- Consistency Groups
- Performance and Monitoring
- Metro node with active-passive storage arrays
Dell EMC Metro node 7.1 Administrator Guide
Migrating thin-capable storage
The following table describes the migration scenarios that are supported and the state of the virtual volumes before, during, and after the migration.
| Migration | Virtual volume state before migration | Virtual volume state during migration | Virtual volume state after migration |
|---|---|---|---|
| Thick to thin | Thin-capable = false | Thin-capable = false | Thin-capable = true |
| Thin-enabled = unavailable | Thin-enabled = unavailable | Thin-enabled = disabled | |
| UNMAP rejected | UNMAP rejected | UNMAP rejected
NOTE:You must set the thin-enabled value to true before UNMAP is processed.
|
|
| Thin to thin (Thin-enabled virtual volume) | Thin-capable = true | Thin-capable = true | Thin-capable = true |
| Thin-enabled = enabled | Thin-enabled = enabled | Thin-enabled = enabled | |
| UNMAP processed | UNMAP processed | UNMAP processed | |
| Thin to thin (Mixed storage array family) | Thin-capable = true | Thin-capable = false | UNMAP rejected |
| Thin-enabled = enabled | Thin-enabled = enabled | UNMAP rejected | |
| Thin to thin (Non thin-enabled virtual volume) | Thin-capable = true | Thin-capable = true | Thin-capable = true |
| Thin-enabled = disabled | Thin-enabled = disabled | Thin-enabled = disabled | |
| UNMAP rejected | UNMAP rejected | UNMAP rejected
NOTE:In this case, UNMAP is intentionally disabled.
|
|
| Thin to thick (Thin-enabled virtual volume) | Thin-capable = true | Thin-capable = false | Thin-capable = false |
| Thin-enabled = enabled | Thin-enabled = enabled | Thin-enabled = unavailable | |
| UNMAP processed | UNMAP rejected | UNMAP rejected | |
| Thin to thick (Non thin-enabled virtual volume) | Thin-capable = true | Thin-capable = false | Thin-capable = false |
| Thin-enabled = disabled | Thin-enabled = unavailable | Thin-enabled = unavailable | |
| UNMAP rejected | UNMAP rejected | UNMAP rejected |
NOTE:
- During migration, a temporary mirror is created to move data from the migration source to the target. Metro node processes UNMAP commands only when both the thin-capable and the thin-enabled attributes are set to true on the virtual volume.
- If the target of migration is a thin-capable device of larger capacity than the source device, then metro node virtual volumes continue to be thin-capable and preserves the earlier provisioned thin-enabled property after the migration completes. To leverage unused capacity, use the virtual-volume expand command.
When migrating from a thin-enabled device to a non-thin device (such as thick device), the volume's thin-enabled attribute stays as enabled although UNMAP is rejected during the migration. After the migration completes successfully, the thin-enabled attribute becomes unavailable because the target device is thick. This behavior is intended because the volume reverts to a thin volume when migration is aborted or failed."
Consider the following when running one time migrations:
- In a thin to thick extent or device migration (with supported virtual volume), if the source is thin-capable and the target is not thin-capable, the supported virtual volumes are not thin-enabled or thin-capable after migration.
VPlexcli:/clusters/cluster-1/devices> dm migration start --paused --name my_migration --from thin_source --to device_thick_1 The source 'thin_source' is thin-capable but the target 'device_thick_1' is not thin-capable. The virtual-volume 'thin_source_vol' will not be thin-enabled or thin-capable after migration. Do you wish to proceed? (Yes/No) no dm migration start: Evaluation of <<dm migration start --paused --name my_migration --from thin_source/ --to device_thick_1_c1/>> failed. cause: Failed to create a new data-migration. cause: Operation was halted by the user VPlexcli:/clusters/cluster-1/devices>
VPlexcli:/clusters/cluster-1/storage-elements/extents> dm migration start --paused --name my_migration --from thin_extent_1 --to thick_extent_1 The source 'thin_extent_1' is thin-capable but the target 'thick_extent_1' is not thin-capable. The virtual-volume 'thin_source_vol' will not be thin-enabled or thin-capable after migration. Do you wish to proceed? (Yes/No) no dm migration start: Evaluation of <<dm migration start --paused --name my_migration --from extent_20 --to extent_31>> failed. cause: Failed to create a new data-migration. cause: Operation was halted by the user VPlexcli:/clusters/cluster-1/storage-elements/extents>
- In a thin to thick extent migration (no supported virtual volume), if the source is thin-capable and the target is not thin-capable, the source loses its thin-capability after migration.
VPlexcli:/clusters/cluster-1/storage-elements/extents> dm migration start --paused --name my_migration --from thin_extent_2 --to thick_extent_1 The source 'thin_extent_2' is thin-capable but the target 'thick_extent_1' is not thin-capable. Thin-capability will be lost after migration. Do you wish to proceed? (Yes/No) no dm migration start: Evaluation of <<dm migration start --paused --name my_migration --from extent_21 --to extent_31>> failed. cause: Failed to create a new data-migration. cause: Operation was halted by the user VPlexcli:/clusters/cluster-1/storage-elements/extents>
Consider the following when committing one time migrations:
- In a thin to thick device migration, the VPlexcli displays a message stating that the virtual volume's thin-properties are disabled.
VPlexcli:/data-migrations/extent-migrations> dm migration commit my_migration --force The virtual-volume 'my_vol' is no longer thin-capable and will not be thin-enabled after migration 'my_migration' is committed. Committed 1 data migration(s) out of 1 requested migration(s). VPlexcli:/data-migrations/extent-migrations>
- In a thin to thin extent or device migration (with supported virtual-volume), if the thin-enabled value is set to false, there is no change after the migration is committed.
VPlexcli:/data-migrations/extent-migrations> dm migration commit my_migration2 --force Committed 1 data migration(s) out of 1 requested migration(s). VPlexcli:/data-migrations/extent-migrations>
- In a thin to thin device migration (with supported virtual volume), if the thin-enabled value is set to true, the virtual volume remains thin-enabled after the migration is committed.
Consider the following when running and committing batch migrations:
- In a thin to thick device or extent migration, during the check-plan phase, the VPlexcli displays a warning stating that the virtual volumes are not thin-capable or thin-enabled after migration.
VPlexcli:/> batch-migrate create-plan --file migration.txt --sources device_thin_1, device_thin_2 --targets device_thick_1, device_thick_2 Extents matching source pattern: device_thin_1, device_thin_2 Extents matching target pattern: device_thick_2, device_thick_1 Creating file /var/log/VPlex/cli/migration.txt as migration plan file. Wrote file /var/log/VPlex/cli/migration.txt. Please review and edit this file, and run this command in the check-plan phase afterward. VPlexcli:/> batch-migrate check-plan --file /var/log/VPlex/cli/migration.txt Checking migration plan file /var/log/VPlex/cli/migration.txt. WARNING: The source 'device_thin_1' is thin-capable but the target 'device_thick_1' is not thin-capable. The virtual-volume 'thin_1' will not be thin-enabled or thin-capable after migration. WARNING: The source 'device_thin_2' is thin-capable but the target 'device_thick_2' is not thin-capable. The virtual-volume 'thin_2' will not be thin-enabled or thin-capable after migration. Plan-check passed with 2 warnings. VPlexcli:/>
- In a thin to thick extent migration (with no supported virtual-volumes), the VPlexcli displays a warning stating that the source loses its thin-capability after migration.
VPlexcli:/> batch-migrate create-plan --file migration.txt --sources extent_thin_1, extent_thin_2 --targets extent_thick_1, extent_thick_2 Extents matching source pattern: extent_thin_1, extent_thin_2 Extents matching target pattern: extent_thick_2, extent_thick_1 Creating file /var/log/VPlex/cli/migration.txt as migration plan file. Wrote file /var/log/VPlex/cli/migration.txt. Please review and edit this file, and run this command in the check-plan phase afterward. VPlexcli:/> batch-migrate check-plan --file /var/log/VPlex/cli/migration.txt Checking migration plan file /var/log/VPlex/cli/migration.txt. WARNING: The source 'device_thin_1' is thin-capable but the target 'device_thick_1' is not thin-capable. Thin-capability will be lost after migration. WARNING: The source 'device_thin_2' is thin-capable but the target 'device_thick_2' is not thin-capable. Thin-capability will be lost after migration. Plan-check passed with 2 warnings. VPlexcli:/>
- For multiple thin-to-thick migrations, the VPlexcli reports the migration problems with multiple warnings. The following example shows two thin-to-thick migrations, where one migration does not have virtual volumes.
VPlexcli:/> batch-migrate check-plan --file /var/log/VPlex/cli/migration.txt Checking migration plan file /var/log/VPlex/cli/migration.txt. WARNING: The source 'device_thin_1' is thin-capable but the target 'device_thick_1' is not thin-capable. The virtual-volume 'thin_1' will not be thin-enabled or thin-capable after migration. PROBLEM: Source device '/clusters/cluster-1/devices/device_thin_2' does not have a volume. WARNING: The source 'device_thin_2' is thin-capable but the target 'device_thick_2' is not thin-capable. Thin-capability will be lost after migration. Plan-check failed with 1 problem and 2 warnings.
- In a simultaneous thin to thick and thick to thin device migration, the virtual volume is not thin-capable or thin-enabled after the batch migration is committed.
Table 2. Simultaneous thin to thick and thick to thin migration Migration Source Target Volume BR0_0 device_thick_4 device_thin_4 source_thick BR0_1 device_thin_5 device_thick_3 source_thin VPlexcli:/> batch-migrate commit --file /var/log/VPlex/cli/migrate.txt The virtual-volume 'source_thin' is no longer thin-capable and will not be thin-enabled after migration 'BR0_1' is committed. Committed 2 of 2 migrations VPlexcli:/>
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