7.9.17 Migrating a fully managed volume to an image-mode volume 7.9.18 Shrinking a volume Migrating a fully managed volume to an image-mode volume enables the IBM Spectrum  Virtualize system to be removed from the data path. This feature might be useful when you  are using the IBM Spectrum Virtualize system as a data mover. To migrate a fully managed volume to an image-mode volume, the following rules apply: Example 7-31 shows a  migratetoimage  command that migrates the data from  volume_A  onto  mdisk10 , and puts the MDisk  mdisk10  into the  STGPool_IMAGE  storage pool. Use the  shrinkvdisksize  command to reduce the capacity that is allocated to the particular  volume by the amount that you specify. You cannot shrink the  real size  of a thin-provisioned  volume to less than its  used size . All capacities (including changes) must be in multiples of  512 bytes. An entire extent is reserved even if it is only partially used. The default capacity  units are MBs. You can use this command to shrink the physical capacity of a volume or to reduce the virtual  capacity of a thin-provisioned volume. These changes do not alter the physical capacity that  is assigned to the volume. Use the following parameters to change volume size: When the virtual capacity of a thin-provisioned volume is changed, the warning threshold is  automatically scaled.  If the volume contains data that is being used, do not shrink the volume without backing up  the data first. The system reduces the capacity of the volume by removing extents as follows: You cannot control which extents are removed. Therefore, you cannot assume that it is  unused space that is removed. Image-mode volumes cannot be reduced in size. To reduce their size, you must first migrate  them to fully-managed mode.  Chapter 7. Volumes  333 GLYPH<SM590000> Extents from those allocated to the volume. GLYPH<SM590000> Arbitrarily chosen extents, or GLYPH<SM590000> For a fully provisioned volume, use the  -size  parameter.  GLYPH<SM590000> For a thin-provisioned volume’s real capacity, use the  -rsize  parameter.  GLYPH<SM590000> For a thin-provisioned volume’s virtual capacity, use the  -size  parameter. GLYPH<SM590000> Cloud snapshots must not be enabled on the source volume. GLYPH<SM590000> The destination MDisk must be greater than or equal to the size of the volume. GLYPH<SM590000> The MDisk that is specified as the target must be in an unmanaged state. GLYPH<SM590000> Regardless of the mode in which the volume starts, it is reported as a managed mode  during the migration. GLYPH<SM590000> If the migration is interrupted by a system recovery or cache problem, the migration  resumes after the recovery completes . Example 7-31 The migratetoimage command IBM_2145:ITSO_CLUSTER:superuser>migratetoimage -vdisk volume_A -mdisk mdisk10 -mdiskgrp  STGPool_IMAGE