The MI_PARTITION_SEGMENTS structure exists only within an MI_PARTITION. It is 0xA8 or 0x0110 bytes in 32-bit and 64-bit Windows, respectively.

Offset (x86) Offset (x64) Definition
0x00 0x00
KEVENT DeleteSubsectionCleanup;
0x10 0x18
KEVENT UnusedSegmentCleanup;
0x20 0x30
ULONG_PTR SubsectionDeletePtes;
0x24 0x38
0x40 0x68
LIST_ENTRY DeleteOnCloseList;
0x48 0x78
KTIMER DeleteOnCloseTimer;
0x70 0xB8
UCHAR DeleteOnCloseTimerActive;
0x74 0xBC
ULONG DeleteOnCloseCount;
0x78 0xC0
LIST_ENTRY UnusedSegmentList;
0x80 0xD0
LIST_ENTRY UnusedSubsectionList;
0x88 0xE0
LIST_ENTRY DeleteSubsectionList;
0x90 0xF0
KEVENT ControlAreaDeleteEvent;
0xA0 0x0108
SINGLE_LIST_ENTRY ControlAreaDeleteList;