The following table describes the migration scenarios that are supported and the state of the virtual volumes before, during, and after the migration.
Table 1. Migration scenarios
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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