The MI_PARTITION_STORES structure exists only within an MI_PARTITION. It is 0x50 or 0x80 bytes in 32-bit and 64-bit Windows, respectively.

Offset (x86) Offset (x64) Definition
0x00 0x00
union {
    struct {
        LONG FlushCompleting : 1;
        LONG FlushInProgress : 31;
    LONG volatile Long;
} WriteAllStoreHintedPages;
0x04 0x04
ULONG VirtualPageFileNumber;
0x08 0x08
ULONG Registered;
0x0C 0x0C
ULONG ReadClusterSizeMax;
0x10 0x10
ULONG EvictFlushRequestcount;
0x14 0x14
ULONG ModifiedWriteDisableCount;
0x18 0x18
ULONG WriteIssueFailures;
0x1C 0x20
ETHREAD *EvictionThread;
0x20 0x28
KEVENT EvictEvent;
0x30 0x40
KEVENT EvictFlushCompleteEvent;
0x40 0x60
SLIST_HEADER WriteSupportSListHead;
0x48 0x70
LONG volatile EvictFlushLock;
0x4C 0x78
RTL_BITMAP *ModifiedWriteFailedBitmap;