diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index cd1c66323af1..f612db48d4f9 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -2654,6 +2654,13 @@ show_import(nvlist_t *config)
 		    errata);
 		break;
 
+	case ZPOOL_STATUS_NON_NATIVE_ASHIFT:
+		printf_color(ANSI_BOLD, gettext("status: "));
+		printf_color(ANSI_YELLOW, gettext("One or more devices are "
+		    "configured to use a non-native block size.\n"
+		    "\tExpect reduced performance.\n"));
+		break;
+
 	default:
 		/*
 		 * No other status can be seen when importing pools.
diff --git a/include/os/linux/kernel/linux/mod_compat.h b/include/os/linux/kernel/linux/mod_compat.h
index 4b83fe413334..1c48df5cbd81 100644
--- a/include/os/linux/kernel/linux/mod_compat.h
+++ b/include/os/linux/kernel/linux/mod_compat.h
@@ -21,6 +21,7 @@
 
 /*
  * Copyright (C) 2016 Gvozden Neskovic <neskovic@gmail.com>.
+ * Copyright (c) 2020 by Delphix. All rights reserved.
  */
 
 #ifndef _MOD_COMPAT_H
@@ -71,6 +72,7 @@ enum scope_prefix_types {
 	zfs_txg,
 	zfs_vdev,
 	zfs_vdev_cache,
+	zfs_vdev_file,
 	zfs_vdev_mirror,
 	zfs_zevent,
 	zfs_zio,
diff --git a/include/sys/vdev.h b/include/sys/vdev.h
index 6dcd20969be6..309ce33be067 100644
--- a/include/sys/vdev.h
+++ b/include/sys/vdev.h
@@ -94,7 +94,6 @@ extern void vdev_rele(vdev_t *);
 extern int vdev_metaslab_init(vdev_t *vd, uint64_t txg);
 extern void vdev_metaslab_fini(vdev_t *vd);
 extern void vdev_metaslab_set_size(vdev_t *);
-extern void vdev_ashift_optimize(vdev_t *);
 extern void vdev_expand(vdev_t *vd, uint64_t txg);
 extern void vdev_split(vdev_t *vd);
 extern void vdev_deadman(vdev_t *vd, char *tag);
diff --git a/man/man5/zfs-module-parameters.5 b/man/man5/zfs-module-parameters.5
index 32f2b94f369a..a5f080e2d1e8 100644
--- a/man/man5/zfs-module-parameters.5
+++ b/man/man5/zfs-module-parameters.5
@@ -772,6 +772,28 @@ regular reads (but there's no reason it has to be the same).
 Default value: \fB32,768\fR.
 .RE
 
+.sp
+.ne 2
+.na
+\fBvdev_file_logical_ashift\fR (ulong)
+.ad
+.RS 12n
+Logical ashift for file-based devices.
+.sp
+Default value: \fB9\fR.
+.RE
+
+.sp
+.ne 2
+.na
+\fBvdev_file_physical_ashift\fR (ulong)
+.ad
+.RS 12n
+Physical ashift for file-based devices.
+.sp
+Default value: \fB9\fR.
+.RE
+
 .sp
 .ne 2
 .na
diff --git a/module/os/freebsd/zfs/sysctl_os.c b/module/os/freebsd/zfs/sysctl_os.c
index 200bbf43d757..b3cb7e7e4374 100644
--- a/module/os/freebsd/zfs/sysctl_os.c
+++ b/module/os/freebsd/zfs/sysctl_os.c
@@ -121,6 +121,7 @@ SYSCTL_NODE(_vfs_zfs, OID_AUTO, zio, CTLFLAG_RW, 0, "ZFS ZIO");
 SYSCTL_NODE(_vfs_zfs_livelist, OID_AUTO, condense, CTLFLAG_RW, 0,
     "ZFS livelist condense");
 SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, cache, CTLFLAG_RW, 0, "ZFS VDEV Cache");
+SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, file, CTLFLAG_RW, 0, "ZFS VDEV file");
 SYSCTL_NODE(_vfs_zfs_vdev, OID_AUTO, mirror, CTLFLAG_RD, 0,
     "ZFS VDEV mirror");
 
diff --git a/module/os/freebsd/zfs/vdev_file.c b/module/os/freebsd/zfs/vdev_file.c
index 4d27751c8893..cf762c5fd61c 100644
--- a/module/os/freebsd/zfs/vdev_file.c
+++ b/module/os/freebsd/zfs/vdev_file.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -40,6 +40,9 @@
 
 static taskq_t *vdev_file_taskq;
 
+unsigned long vdev_file_logical_ashift = SPA_MINBLOCKSHIFT;
+unsigned long vdev_file_physical_ashift = SPA_MINBLOCKSHIFT;
+
 void
 vdev_file_init(void)
 {
@@ -167,8 +170,8 @@ vdev_file_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
 	}
 
 	*max_psize = *psize = zfa.zfa_size;
-	*logical_ashift = SPA_MINBLOCKSHIFT;
-	*physical_ashift = SPA_MINBLOCKSHIFT;
+	*logical_ashift = vdev_file_logical_ashift;
+	*physical_ashift = vdev_file_physical_ashift;
 
 	return (0);
 }
@@ -326,3 +329,8 @@ vdev_ops_t vdev_disk_ops = {
 };
 
 #endif
+
+ZFS_MODULE_PARAM(zfs_vdev_file, vdev_file_, logical_ashift, ULONG, ZMOD_RW,
+	"Logical ashift for file-based devices");
+ZFS_MODULE_PARAM(zfs_vdev_file, vdev_file_, physical_ashift, ULONG, ZMOD_RW,
+	"Physical ashift for file-based devices");
diff --git a/module/os/linux/zfs/vdev_file.c b/module/os/linux/zfs/vdev_file.c
index a4e71ca40788..423ce858144c 100644
--- a/module/os/linux/zfs/vdev_file.c
+++ b/module/os/linux/zfs/vdev_file.c
@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2011, 2016 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2020 by Delphix. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -45,6 +45,17 @@
 
 static taskq_t *vdev_file_taskq;
 
+/*
+ * By default, the logical/physical ashift for file vdevs is set to
+ * SPA_MINBLOCKSHIFT (9). This allows all file vdevs to use 512B (1 << 9)
+ * blocksizes. Users may opt to change one or both of these for testing
+ * or performance reasons. Care should be taken as these values will
+ * impact the vdev_ashift setting which can only be set at vdev creation
+ * time.
+ */
+unsigned long vdev_file_logical_ashift = SPA_MINBLOCKSHIFT;
+unsigned long vdev_file_physical_ashift = SPA_MINBLOCKSHIFT;
+
 static void
 vdev_file_hold(vdev_t *vd)
 {
@@ -159,8 +170,8 @@ vdev_file_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
 	}
 
 	*max_psize = *psize = zfa.zfa_size;
-	*logical_ashift = SPA_MINBLOCKSHIFT;
-	*physical_ashift = SPA_MINBLOCKSHIFT;
+	*logical_ashift = vdev_file_logical_ashift;
+	*physical_ashift = vdev_file_physical_ashift;
 
 	return (0);
 }
@@ -346,3 +357,8 @@ vdev_ops_t vdev_disk_ops = {
 };
 
 #endif
+
+ZFS_MODULE_PARAM(zfs_vdev_file, vdev_file_, logical_ashift, ULONG, ZMOD_RW,
+	"Logical ashift for file-based devices");
+ZFS_MODULE_PARAM(zfs_vdev_file, vdev_file_, physical_ashift, ULONG, ZMOD_RW,
+	"Physical ashift for file-based devices");
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 7c21e9b428cc..53ebf629ee3c 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -9434,8 +9434,6 @@ l2arc_add_vdev(spa_t *spa, vdev_t *vd)
 
 	ASSERT(!l2arc_vdev_present(vd));
 
-	vdev_ashift_optimize(vd);
-
 	/*
 	 * Create a new l2arc device entry.
 	 */
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 8c662f6b0666..532f04b91ca1 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -5762,7 +5762,6 @@ spa_create(const char *pool, nvlist_t *nvroot, nvlist_t *props,
 		for (int c = 0; error == 0 && c < rvd->vdev_children; c++) {
 			vdev_t *vd = rvd->vdev_child[c];
 
-			vdev_ashift_optimize(vd);
 			vdev_metaslab_set_size(vd);
 			vdev_expand(vd, txg);
 		}
diff --git a/module/zfs/spa_config.c b/module/zfs/spa_config.c
index 81059c69d47a..dacba127dcfa 100644
--- a/module/zfs/spa_config.c
+++ b/module/zfs/spa_config.c
@@ -577,10 +577,8 @@ spa_config_update(spa_t *spa, int what)
 			    (tvd->vdev_islog && tvd->vdev_removing))
 				continue;
 
-			if (tvd->vdev_ms_array == 0) {
-				vdev_ashift_optimize(tvd);
+			if (tvd->vdev_ms_array == 0)
 				vdev_metaslab_set_size(tvd);
-			}
 			vdev_expand(tvd, txg);
 		}
 	}
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index 0a3b8bd83ba2..a94101485c94 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -1672,6 +1672,38 @@ vdev_set_deflate_ratio(vdev_t *vd)
 	}
 }
 
+/*
+ * Maximize performance by inflating the configured ashift for top level
+ * vdevs to be as close to the physical ashift as possible while maintaining
+ * administrator defined limits and ensuring it doesn't go below the
+ * logical ashift.
+ */
+static void
+vdev_ashift_optimize(vdev_t *vd)
+{
+	ASSERT(vd == vd->vdev_top);
+
+	if (vd->vdev_ashift < vd->vdev_physical_ashift) {
+		vd->vdev_ashift = MIN(
+		    MAX(zfs_vdev_max_auto_ashift, vd->vdev_ashift),
+		    MAX(zfs_vdev_min_auto_ashift,
+		    vd->vdev_physical_ashift));
+	} else {
+		/*
+		 * If the logical and physical ashifts are the same, then
+		 * we ensure that the top-level vdev's ashift is not smaller
+		 * than our minimum ashift value. For the unusual case
+		 * where logical ashift > physical ashift, we can't cap
+		 * the calculated ashift based on max ashift as that
+		 * would cause failures.
+		 * We still check if we need to increase it to match
+		 * the min ashift.
+		 */
+		vd->vdev_ashift = MAX(zfs_vdev_min_auto_ashift,
+		    vd->vdev_ashift);
+	}
+}
+
 /*
  * Prepare a virtual device for access.
  */
@@ -1830,16 +1862,17 @@ vdev_open(vdev_t *vd)
 		return (SET_ERROR(EINVAL));
 	}
 
+	/*
+	 * We can always set the logical/physical ashift members since
+	 * their values are only used to calculate the vdev_ashift when
+	 * the device is first added to the config. These values should
+	 * not be used for anything else since they may change whenever
+	 * the device is reopened and we don't store them in the label.
+	 */
 	vd->vdev_physical_ashift =
 	    MAX(physical_ashift, vd->vdev_physical_ashift);
-	vd->vdev_logical_ashift = MAX(logical_ashift, vd->vdev_logical_ashift);
-	vd->vdev_ashift = MAX(vd->vdev_logical_ashift, vd->vdev_ashift);
-
-	if (vd->vdev_logical_ashift > ASHIFT_MAX) {
-		vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
-		    VDEV_AUX_ASHIFT_TOO_BIG);
-		return (SET_ERROR(EDOM));
-	}
+	vd->vdev_logical_ashift = MAX(logical_ashift,
+	    vd->vdev_logical_ashift);
 
 	if (vd->vdev_asize == 0) {
 		/*
@@ -1848,6 +1881,24 @@ vdev_open(vdev_t *vd)
 		 */
 		vd->vdev_asize = asize;
 		vd->vdev_max_asize = max_asize;
+
+		/*
+		 * If the vdev_ashift was not overriden at creation time,
+		 * then set it the logical ashift and optimize the ashift.
+		 */
+		if (vd->vdev_ashift == 0) {
+			vd->vdev_ashift = vd->vdev_logical_ashift;
+
+			if (vd->vdev_logical_ashift > ASHIFT_MAX) {
+				vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
+				    VDEV_AUX_ASHIFT_TOO_BIG);
+				return (SET_ERROR(EDOM));
+			}
+
+			if (vd->vdev_top == vd) {
+				vdev_ashift_optimize(vd);
+			}
+		}
 		if (vd->vdev_ashift != 0 && (vd->vdev_ashift < ASHIFT_MIN ||
 		    vd->vdev_ashift > ASHIFT_MAX)) {
 			vdev_set_state(vd, B_TRUE, VDEV_STATE_CANT_OPEN,
@@ -2444,35 +2495,6 @@ vdev_metaslab_set_size(vdev_t *vd)
 	ASSERT3U(vd->vdev_ms_shift, >=, SPA_MAXBLOCKSHIFT);
 }
 
-/*
- * Maximize performance by inflating the configured ashift for top level
- * vdevs to be as close to the physical ashift as possible while maintaining
- * administrator defined limits and ensuring it doesn't go below the
- * logical ashift.
- */
-void
-vdev_ashift_optimize(vdev_t *vd)
-{
-	if (vd == vd->vdev_top) {
-		if (vd->vdev_ashift < vd->vdev_physical_ashift) {
-			vd->vdev_ashift = MIN(
-			    MAX(zfs_vdev_max_auto_ashift, vd->vdev_ashift),
-			    MAX(zfs_vdev_min_auto_ashift,
-			    vd->vdev_physical_ashift));
-		} else {
-			/*
-			 * Unusual case where logical ashift > physical ashift
-			 * so we can't cap the calculated ashift based on max
-			 * ashift as that would cause failures.
-			 * We still check if we need to increase it to match
-			 * the min ashift.
-			 */
-			vd->vdev_ashift = MAX(zfs_vdev_min_auto_ashift,
-			    vd->vdev_ashift);
-		}
-	}
-}
-
 void
 vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg)
 {
diff --git a/module/zfs/vdev_mirror.c b/module/zfs/vdev_mirror.c
index 5e1060f127c9..71b5adbbd06a 100644
--- a/module/zfs/vdev_mirror.c
+++ b/module/zfs/vdev_mirror.c
@@ -391,7 +391,7 @@ vdev_mirror_open(vdev_t *vd, uint64_t *asize, uint64_t *max_asize,
 		*max_asize = MIN(*max_asize - 1, cvd->vdev_max_asize - 1) + 1;
 		*logical_ashift = MAX(*logical_ashift, cvd->vdev_ashift);
 		*physical_ashift = MAX(*physical_ashift,
-		    vd->vdev_physical_ashift);
+		    cvd->vdev_physical_ashift);
 	}
 
 	if (numerrors == vd->vdev_children) {
diff --git a/tests/zfs-tests/include/tunables.cfg b/tests/zfs-tests/include/tunables.cfg
index 34544e9f4845..248a9fb3a001 100644
--- a/tests/zfs-tests/include/tunables.cfg
+++ b/tests/zfs-tests/include/tunables.cfg
@@ -77,6 +77,7 @@ TRIM_TXG_BATCH			trim.txg_batch			zfs_trim_txg_batch
 TXG_HISTORY			txg.history			zfs_txg_history
 TXG_TIMEOUT			txg.timeout			zfs_txg_timeout
 UNLINK_SUSPEND_PROGRESS		UNSUPPORTED			zfs_unlink_suspend_progress
+VDEV_FILE_PHYSICAL_ASHIFT	vdev.file.physical_ashift	vdev_file_physical_ashift
 VDEV_MIN_MS_COUNT		vdev.min_ms_count		zfs_vdev_min_ms_count
 VDEV_VALIDATE_SKIP		vdev.validate_skip		vdev_validate_skip
 VOL_INHIBIT_DEV			UNSUPPORTED			zvol_inhibit_dev
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_add/add-o_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_add/add-o_ashift.ksh
index d9ae88e0792e..89cc4b0d3082 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_add/add-o_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_add/add-o_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -35,13 +36,15 @@
 # STRATEGY:
 #	1. Create a pool with default values.
 #	2. Verify 'zpool add -o ashift=<n>' works with allowed values (9-16).
-#	3. Verify 'zpool add -o ashift=<n>' doesn't accept other invalid values.
+#	3. Verify setting kernel tunable for file vdevs works correctly.
+#	4. Verify 'zpool add -o ashift=<n>' doesn't accept other invalid values.
 #
 
 verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	poolexists $TESTPOOL && destroy_pool $TESTPOOL
 	rm -f $disk1 $disk2
 }
@@ -54,6 +57,8 @@ disk2=$TEST_BASE_DIR/disk2
 log_must mkfile $SIZE $disk1
 log_must mkfile $SIZE $disk2
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+
 typeset ashifts=("9" "10" "11" "12" "13" "14" "15" "16")
 for ashift in ${ashifts[@]}
 do
@@ -69,6 +74,24 @@ do
 	log_must zpool destroy $TESTPOOL
 	log_must zpool labelclear $disk1
 	log_must zpool labelclear $disk2
+
+	#
+	# Make sure we can also set the ashift using the tunable.
+	#
+	log_must zpool create $TESTPOOL $disk1
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $ashift
+	log_must zpool add $TESTPOOL $disk2
+	verify_ashift $disk2 $ashift
+	if [[ $? -ne 0 ]]
+	then
+		log_fail "Device was added without setting ashift value to "\
+		    "$ashift"
+	fi
+	# clean things for the next run
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
+	log_must zpool destroy $TESTPOOL
+	log_must zpool labelclear $disk1
+	log_must zpool labelclear $disk2
 done
 
 typeset badvals=("off" "on" "1" "8" "17" "1b" "ff" "-")
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_add/add_prop_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_add/add_prop_ashift.ksh
index 37887f3d115e..4637fe0d84a3 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_add/add_prop_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_add/add_prop_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -43,6 +44,7 @@ verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	poolexists $TESTPOOL && destroy_pool $TESTPOOL
 	log_must rm -f $disk1 $disk2
 }
@@ -55,6 +57,14 @@ disk2=$TEST_BASE_DIR/disk2
 log_must mkfile $SIZE $disk1
 log_must mkfile $SIZE $disk2
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+#
+# Set the file vdev's ashift to the max. Overriding
+# the ashift using the -o ashift property should still
+# be honored.
+#
+log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT 16
+
 typeset ashifts=("9" "10" "11" "12" "13" "14" "15" "16")
 for ashift in ${ashifts[@]}
 do
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_attach/attach-o_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_attach/attach-o_ashift.ksh
index 9af011cb04d8..618c6992edb4 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_attach/attach-o_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_attach/attach-o_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -41,6 +42,7 @@ verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	poolexists $TESTPOOL1 && destroy_pool $TESTPOOL1
 	rm -f $disk1 $disk2
 }
@@ -53,6 +55,14 @@ disk2=$TEST_BASE_DIR/disk2
 log_must truncate -s $SIZE $disk1
 log_must truncate -s $SIZE $disk2
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+#
+# Set the file vdev's ashift to the max. Overriding
+# the ashift using the -o ashift property should still
+# be honored.
+#
+log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT 16
+
 typeset ashifts=("9" "10" "11" "12" "13" "14" "15" "16")
 for ashift in ${ashifts[@]}
 do
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace-o_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace-o_ashift.ksh
index 0fc2c69ba143..1b18b1297a78 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace-o_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace-o_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -41,6 +42,7 @@ verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	poolexists $TESTPOOL1 && destroy_pool $TESTPOOL1
 	rm -f $disk1 $disk2
 }
@@ -53,6 +55,14 @@ disk2=$TEST_BASE_DIR/disk2
 log_must truncate -s $SIZE $disk1
 log_must truncate -s $SIZE $disk2
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+#
+# Set the file vdev's ashift to the max. Overriding
+# the ashift using the -o ashift property should still
+# be honored.
+#
+log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT 16
+
 typeset ashifts=("9" "10" "11" "12" "13" "14" "15" "16")
 for ashift in ${ashifts[@]}
 do
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace_prop_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace_prop_ashift.ksh
index fbdd44ceb581..f076f26818eb 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace_prop_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_replace/replace_prop_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -43,6 +44,7 @@ verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	poolexists $TESTPOOL1 && destroy_pool $TESTPOOL1
 	rm -f $disk1 $disk2
 }
@@ -55,6 +57,14 @@ disk2=$TEST_BASE_DIR/disk2
 log_must truncate -s $SIZE $disk1
 log_must truncate -s $SIZE $disk2
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+#
+# Set the file vdev's ashift to the max. Overriding
+# the ashift using the -o ashift property should still
+# be honored.
+#
+log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT 16
+
 typeset ashifts=("9" "10" "11" "12" "13" "14" "15" "16")
 for ashift in ${ashifts[@]}
 do
diff --git a/tests/zfs-tests/tests/functional/cli_root/zpool_set/zpool_set_ashift.ksh b/tests/zfs-tests/tests/functional/cli_root/zpool_set/zpool_set_ashift.ksh
index 86e692fadafc..09b5f50d5e18 100755
--- a/tests/zfs-tests/tests/functional/cli_root/zpool_set/zpool_set_ashift.ksh
+++ b/tests/zfs-tests/tests/functional/cli_root/zpool_set/zpool_set_ashift.ksh
@@ -22,6 +22,7 @@
 
 #
 # Copyright 2017, loli10K. All rights reserved.
+# Copyright (c) 2020 by Delphix. All rights reserved.
 #
 
 . $STF_SUITE/include/libtest.shlib
@@ -41,6 +42,7 @@ verify_runnable "global"
 
 function cleanup
 {
+	log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT $orig_ashift
 	destroy_pool $TESTPOOL1
 	rm -f $disk
 }
@@ -52,6 +54,14 @@ log_onexit cleanup
 
 log_assert "zpool set can modify 'ashift' property"
 
+orig_ashift=$(get_tunable VDEV_FILE_PHYSICAL_ASHIFT)
+#
+# Set the file vdev's ashift to the max. Overriding
+# the ashift using the -o ashift property should still
+# be honored.
+#
+log_must set_tunable64 VDEV_FILE_PHYSICAL_ASHIFT 16
+
 disk=$TEST_BASE_DIR/disk
 log_must mkfile $SIZE $disk
 log_must zpool create $TESTPOOL1 $disk