diff --git a/sys/dev/aac/aac.c b/sys/dev/aac/aac.c
index 59c1a265e1cf..d77f91f4d4b1 100644
--- a/sys/dev/aac/aac.c
+++ b/sys/dev/aac/aac.c
@@ -377,7 +377,9 @@ aac_get_container_info(struct aac_softc *sc, struct aac_fib *fib, int cid)
 	struct aac_mntinfo *mi;
 
 	mi = (struct aac_mntinfo *)&fib->data[0];
-	mi->Command = VM_NameServe;
+	/* use 64-bit LBA if enabled */
+	mi->Command = (sc->flags & AAC_FLAGS_LBA_64BIT) ?
+	    VM_NameServe64 : VM_NameServe;
 	mi->MntType = FT_FILESYS;
 	mi->MntCount = cid;
 
@@ -1802,6 +1804,11 @@ aac_check_firmware(struct aac_softc *sc)
 		sc->flags |= AAC_FLAGS_RAW_IO;
 		device_printf(sc->aac_dev, "Enable Raw I/O\n");
 	}
+	if ((sc->flags & AAC_FLAGS_RAW_IO) &&
+	    (sc->flags & AAC_FLAGS_ARRAY_64BIT)) {
+		sc->flags |= AAC_FLAGS_LBA_64BIT;
+		device_printf(sc->aac_dev, "Enable 64-bit array\n");
+	}
 
 	return (0);
 }
diff --git a/sys/dev/aac/aac_disk.c b/sys/dev/aac/aac_disk.c
index 24b0771971b7..6568a0d35be8 100644
--- a/sys/dev/aac/aac_disk.c
+++ b/sys/dev/aac/aac_disk.c
@@ -343,6 +343,9 @@ aac_disk_attach(device_t dev)
 	 * disk!
 	 */
 	sc->ad_size = sc->ad_container->co_mntobj.Capacity;
+	if (sc->ad_controller->flags & AAC_FLAGS_LBA_64BIT)
+		sc->ad_size += (u_int64_t)
+			sc->ad_container->co_mntobj.CapacityHigh << 32;
 	if (sc->ad_size >= (2 * 1024 * 1024)) {		/* 2GB */
 		sc->ad_heads = 255;
 		sc->ad_sectors = 63;
@@ -355,9 +358,9 @@ aac_disk_attach(device_t dev)
 	}
 	sc->ad_cylinders = (sc->ad_size / (sc->ad_heads * sc->ad_sectors));
 
-	device_printf(dev, "%uMB (%u sectors)\n",
-		      sc->ad_size / ((1024 * 1024) / AAC_BLOCK_SIZE),
-		      sc->ad_size);
+	device_printf(dev, "%juMB (%ju sectors)\n",
+		      (intmax_t)sc->ad_size / ((1024 * 1024) / AAC_BLOCK_SIZE),
+		      (intmax_t)sc->ad_size);
 
 	/* attach a generic disk device to ourselves */
 	sc->unit = device_get_unit(dev);
diff --git a/sys/dev/aac/aacreg.h b/sys/dev/aac/aacreg.h
index dae21a48b5cf..5221bb26d7f7 100644
--- a/sys/dev/aac/aacreg.h
+++ b/sys/dev/aac/aacreg.h
@@ -1140,6 +1140,7 @@ struct aac_mntobj {
 		u_int32_t	pad[8];
 	} ObjExtension;
 	u_int32_t			AlterEgoId;
+	u_int32_t			CapacityHigh;
 } __packed;
 
 struct aac_mntinfo {
diff --git a/sys/dev/aac/aacvar.h b/sys/dev/aac/aacvar.h
index c39d7c95d219..2b204723f88e 100644
--- a/sys/dev/aac/aacvar.h
+++ b/sys/dev/aac/aacvar.h
@@ -133,7 +133,7 @@ struct aac_disk
 	int				ad_cylinders;
 	int				ad_heads;
 	int				ad_sectors;
-	u_int32_t			ad_size;
+	u_int64_t			ad_size;
 	int				unit;
 };
 
@@ -392,6 +392,7 @@ struct aac_softc
 #define AAC_FLAGS_NEW_COMM	(1 << 11)	/* New comm. interface supported */
 #define AAC_FLAGS_RAW_IO	(1 << 12)	/* Raw I/O interface */
 #define AAC_FLAGS_ARRAY_64BIT	(1 << 13)	/* 64-bit array size */
+#define	AAC_FLAGS_LBA_64BIT	(1 << 14)	/* 64-bit LBA support */
 
 	u_int32_t		supported_options;
 	u_int32_t		scsi_method_id;