In this case, an environment with Copy Services (FlashCopy, Metro Mirror, Global Mirror, and  Volume Mirroring) and typical workloads, disabling SVC cache is detrimental to overall  performance. In cases where there are no advanced functions and extremely high IOPS rate  is required, disabling the cache might help. Attention:  Carefully evaluate the impact to the entire system with quantitative analysis  before and after making this change The following section describes additional and brief considerations regarding volumes. You can protect volumes to prevent active volumes or host mappings from being deleted. IBM  FlashSystem 9100 supports a global setting that prevents these objects from being deleted if  the system detects recent I/O activity. When you delete a volume, the system verifies whether it is a part of a host mapping,  FlashCopy mapping, or remote-copy relationship. In these cases, the system fails to delete  the volume, unless the  -force  parameter is specified. Using the  -force  parameter can lead to  unintentional deletions of volumes that are still active. Active means that the system detected  recent I/O activity to the volume from any host.  To prevent an active volume from being deleted unintentionally, administrators can use a  global system setting to enable volume protection. They can also specify a time period that  the volume must be idle before it can be deleted. If volume protection is enabled and the time  period is not expired, the volume deletion fails even if the -force parameter is used. Consider enabling volume protection by using  chsystem vdiskprotectionenabled yes  -vdiskprotectiontime <value_in_minutes> .  Note:  Volume protection cannot be overridden by the use of the  -force  flag in the affected  CLI commands. Volume protection must be disabled to permit an activity that is currently  blocked. Fully allocated and thin-provisioned volumes can have their sizes increased or decreased. A  volume can be expanded with concurrent I/Os for some operating systems, but you should  never attempt to shrink a volume in use that contains data, because volume capacity is  removed from the end of the disk, whether or not that capacity is in use by a server.  Remember that a volume cannot be expanded or shrunk during its quick initialization process. You can expand volumes for the following reasons: Expanding a volume 5.13.2 Volume resize 5.13.1 Volume protection 5.13 Additional considerations GLYPH<SM590000> To increase the available capacity on a particular volume that is already mapped to a host. GLYPH<SM590000> To increase the size of a volume aiming to make it match the size of the source or master  volume so that it can be used in a FlashCopy mapping or Metro Mirror relationship. Chapter 5. Volumes  139