On a ESXi 5.5 we are trying to take snapshot and read the changes while CBT is enabled on VM. The API fails to give the information and throws a FileFault. Following are the error lines that I see in vmware log:
DISKLIB-CTK : Auto blocksize for size 230686720 is 128.
DISKLIB-CTK : Auto blocksize for size 377487360 is 256.
DISKLIB-CBT : Initializing ESX kernel change tracking for fid 1505332471.
DISKLIB-CBT : Successfuly created cbt node 59b98cf7-cbt.
DISKLIB-CBT : Opening cbt node /vmfs/devices/cbt/59b98cf7-cbt
OBJLIB-FILEBE : FileBEIoctl: ioctl operation failed on '/vmfs/devices/cbt/59b98cf7-cbt' : Inappropriate ioctl for device (1638402)
ESXMapperGetPhysicalMapping: Failed to get physical mapping: 190004 Inappropriate ioctl for device
DISKLIB-CBT : Initializing ESX kernel change tracking for fid 1406045430.
DISK: Change tracking for disk scsi0:0 is now enabled.
DISKLIB-CBT : Successfuly created cbt node 53ce8cf6-cbt.
DISKLIB-CBT : Opening cbt node /vmfs/devices/cbt/53ce8cf6-cbt
OBJLIB-FILEBE : FileBEIoctl: ioctl operation failed on '/vmfs/devices/cbt/53ce8cf6-cbt' : Inappropriate ioctl for device (1638402)
ESXMapperGetPhysicalMapping: Failed to get physical mapping: 190004 Inappropriate ioctl for device