diff --git a/sys/dev/xen/blkback/blkback.c b/sys/dev/xen/blkback/blkback.c
--- a/sys/dev/xen/blkback/blkback.c
+++ b/sys/dev/xen/blkback/blkback.c
@@ -145,6 +145,8 @@
  */
 #define	XBB_MAX_SEGMENTS_PER_REQLIST XBB_MAX_SEGMENTS_PER_REQUEST
 
+#define XBD_SECTOR_SHFT		9
+
 /*--------------------------- Forward Declarations ---------------------------*/
 struct xbb_softc;
 struct xbb_xen_req;
@@ -1150,7 +1152,9 @@
 	if (*reqlist == NULL) {
 		*reqlist = nreqlist;
 		nreqlist->operation = ring_req->operation;
-		nreqlist->starting_sector_number = ring_req->sector_number;
+		nreqlist->starting_sector_number =
+		    (ring_req->sector_number << XBD_SECTOR_SHFT) >>
+		    xbb->sector_size_shift;
 		STAILQ_INSERT_TAIL(&xbb->reqlist_pending_stailq, nreqlist,
 				   links);
 	}
@@ -2476,13 +2480,13 @@
 	xbb->sector_size = 512;
 
 	/*
-	 * Sanity check.  The media size has to be at least one
-	 * sector long.
+	 * Sanity check.  The media size must be a multiple of the sector
+	 * size.
 	 */
-	if (xbb->media_size < xbb->sector_size) {
+	if ((xbb->media_size % xbb->sector_size) != 0) {
 		error = EINVAL;
 		xenbus_dev_fatal(xbb->dev, error,
-				 "file %s size %ju < block size %u",
+				 "file %s size %ju not multiple of block size %u",
 				 xbb->dev_name,
 				 (uintmax_t)xbb->media_size,
 				 xbb->sector_size);
@@ -3086,9 +3090,13 @@
 			return (error);
 		}
 
+		/*
+		 * The 'sectors' node is special and always contains the size
+		 * in units of 512b, regardless of the value in 'sector-size'.
+		 */
 		leaf = "sectors";
-		error = xs_printf(xst, our_path, leaf,
-				  "%"PRIu64, xbb->media_num_sectors);
+		error = xs_printf(xst, our_path, leaf, "%ju",
+		    (uintmax_t)(xbb->media_size >> XBD_SECTOR_SHFT));
 		if (error != 0)
 			break;
 
diff --git a/sys/dev/xen/blkfront/blkfront.c b/sys/dev/xen/blkfront/blkfront.c
--- a/sys/dev/xen/blkfront/blkfront.c
+++ b/sys/dev/xen/blkfront/blkfront.c
@@ -158,7 +158,8 @@
 static void
 xbd_mksegarray(bus_dma_segment_t *segs, int nsegs,
     grant_ref_t * gref_head, int otherend_id, int readonly,
-    grant_ref_t * sg_ref, struct blkif_request_segment *sg)
+    grant_ref_t * sg_ref, struct blkif_request_segment *sg,
+    unsigned int sector_size)
 {
 	struct blkif_request_segment *last_block_sg = sg + nsegs;
 	vm_paddr_t buffer_ma;
@@ -166,9 +167,9 @@
 	int ref;
 
 	while (sg < last_block_sg) {
-		KASSERT(segs->ds_addr % (1 << XBD_SECTOR_SHFT) == 0,
+		KASSERT((segs->ds_addr & (sector_size - 1)) == 0,
 		    ("XEN disk driver I/O must be sector aligned"));
-		KASSERT(segs->ds_len % (1 << XBD_SECTOR_SHFT) == 0,
+		KASSERT((segs->ds_len & (sector_size - 1)) == 0,
 		    ("XEN disk driver I/Os must be a multiple of "
 		    "the sector length"));
 		buffer_ma = segs->ds_addr;
@@ -241,7 +242,8 @@
 		xbd_mksegarray(segs, nsegs, &cm->cm_gref_head,
 		    xenbus_get_otherend_id(sc->xbd_dev),
 		    cm->cm_operation == BLKIF_OP_WRITE,
-		    cm->cm_sg_refs, ring_req->seg);
+		    cm->cm_sg_refs, ring_req->seg,
+		    sc->xbd_disk->d_sectorsize);
 	} else {
 		blkif_request_indirect_t *ring_req;
 
@@ -259,7 +261,8 @@
 		xbd_mksegarray(segs, nsegs, &cm->cm_gref_head,
 		    xenbus_get_otherend_id(sc->xbd_dev),
 		    cm->cm_operation == BLKIF_OP_WRITE,
-		    cm->cm_sg_refs, cm->cm_indirectionpages);
+		    cm->cm_sg_refs, cm->cm_indirectionpages,
+		    sc->xbd_disk->d_sectorsize);
 		memcpy(ring_req->indirect_grefs, &cm->cm_indirectionrefs,
 		    sizeof(grant_ref_t) * sc->xbd_max_request_indirectpages);
 	}
@@ -359,7 +362,9 @@
 	}
 
 	cm->cm_bp = bp;
-	cm->cm_sector_number = (blkif_sector_t)bp->bio_pblkno;
+	cm->cm_sector_number =
+	    ((blkif_sector_t)bp->bio_pblkno * sc->xbd_disk->d_sectorsize) >>
+	    XBD_SECTOR_SHFT;
 
 	switch (bp->bio_cmd) {
 	case BIO_READ:
@@ -631,7 +636,7 @@
 		cm->cm_data = virtual;
 		cm->cm_datalen = chunk;
 		cm->cm_operation = BLKIF_OP_WRITE;
-		cm->cm_sector_number = offset / dp->d_sectorsize;
+		cm->cm_sector_number = offset >> XBD_SECTOR_SHFT;
 		cm->cm_complete = xbd_dump_complete;
 
 		xbd_enqueue_cm(cm, XBD_Q_READY);
@@ -1025,7 +1030,19 @@
 	sc->xbd_disk->d_stripesize = phys_sector_size;
 	sc->xbd_disk->d_stripeoffset = 0;
 
-	sc->xbd_disk->d_mediasize = sectors * sector_size;
+	/*
+	 * The 'sectors' xenbus node is always in units of 512b, regardless of
+	 * the 'sector-size' xenbus node value.
+	 */
+	sc->xbd_disk->d_mediasize = sectors << XBD_SECTOR_SHFT;
+	if ((sc->xbd_disk->d_mediasize % sc->xbd_disk->d_sectorsize) != 0) {
+		error = EINVAL;
+		xenbus_dev_fatal(sc->xbd_dev, error,
+		    "Disk size (%ju) not a multiple of sector size (%ju)",
+		    (uintmax_t)sc->xbd_disk->d_mediasize,
+		    (uintmax_t)sc->xbd_disk->d_sectorsize);
+		return (error);
+	}
 	sc->xbd_disk->d_maxsize = sc->xbd_max_request_size;
 	sc->xbd_disk->d_flags = DISKFLAG_UNMAPPED_BIO;
 	if ((sc->xbd_flags & (XBDF_FLUSH|XBDF_BARRIER)) != 0) {
@@ -1310,7 +1327,7 @@
 	/* Allocate datastructures based on negotiated values. */
 	err = bus_dma_tag_create(
 	    bus_get_dma_tag(sc->xbd_dev),	/* parent */
-	    512, PAGE_SIZE,			/* algnmnt, boundary */
+	    sector_size, PAGE_SIZE,		/* algnmnt, boundary */
 	    BUS_SPACE_MAXADDR,			/* lowaddr */
 	    BUS_SPACE_MAXADDR,			/* highaddr */
 	    NULL, NULL,				/* filter, filterarg */
@@ -1380,13 +1397,17 @@
 
 	if (sc->xbd_disk == NULL) {
 		device_printf(dev, "%juMB <%s> at %s",
-		    (uintmax_t) sectors / (1048576 / sector_size),
+		    (uintmax_t)((sectors << XBD_SECTOR_SHFT) / 1048576),
 		    device_get_desc(dev),
 		    xenbus_get_node(dev));
 		bus_print_child_footer(device_get_parent(dev), dev);
 
-		xbd_instance_create(sc, sectors, sc->xbd_vdevice, binfo,
+		err = xbd_instance_create(sc, sectors, sc->xbd_vdevice, binfo,
 		    sector_size, phys_sector_size);
+		if (err != 0) {
+			xenbus_dev_fatal(dev, err, "Unable to create instance");
+			return;
+		}
 	}
 
 	(void)xenbus_set_state(dev, XenbusStateConnected);