diff --git a/tests/runfiles/common.run b/tests/runfiles/common.run
index 326eb2a44d37..ad131664698b 100644
--- a/tests/runfiles/common.run
+++ b/tests/runfiles/common.run
@@ -672,7 +672,9 @@ post =
 tags = ['functional', 'deadman']
 
 [tests/functional/dedup]
-tests = ['dedup_quota']
+tests = ['dedup_legacy_create', 'dedup_fdt_create', 'dedup_fdt_import',
+    'dedup_legacy_create', 'dedup_legacy_import', 'dedup_legacy_fdt_upgrade',
+    'dedup_legacy_fdt_mixed', 'dedup_quota']
 pre =
 post =
 tags = ['functional', 'dedup']
diff --git a/tests/zfs-tests/tests/Makefile.am b/tests/zfs-tests/tests/Makefile.am
index 9dcb097e2b38..bbeabc6dfb42 100644
--- a/tests/zfs-tests/tests/Makefile.am
+++ b/tests/zfs-tests/tests/Makefile.am
@@ -1424,6 +1424,12 @@ nobase_dist_datadir_zfs_tests_tests_SCRIPTS += \
 	functional/deadman/deadman_zio.ksh \
 	functional/dedup/cleanup.ksh \
 	functional/dedup/setup.ksh \
+	functional/dedup/dedup_fdt_create.ksh \
+	functional/dedup/dedup_fdt_import.ksh \
+	functional/dedup/dedup_legacy_create.ksh \
+	functional/dedup/dedup_legacy_import.ksh \
+	functional/dedup/dedup_legacy_fdt_upgrade.ksh \
+	functional/dedup/dedup_legacy_fdt_mixed.ksh \
 	functional/dedup/dedup_quota.ksh \
 	functional/delegate/cleanup.ksh \
 	functional/delegate/setup.ksh \
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_fdt_create.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_fdt_create.ksh
new file mode 100755
index 000000000000..83c4d7c8e2aa
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_fdt_create.ksh
@@ -0,0 +1,99 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Simple test of dedup table operations (FDT)
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "basic dedup (FDT) operations work"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with fast dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=enabled \
+    -O dedup=on \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# confirm the feature is enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-sha256"
+
+# create a file. this is four full blocks, so will produce four entries in the
+# dedup table
+log_must dd if=/dev/urandom of=/$TESTPOOL/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should now be active
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# single containing object in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 1
+obj=$(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | awk '{ print $NF }')
+
+# with only one ZAP inside
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-sha256-zap- | wc -l) -eq 1
+
+# copy the file
+log_must cp /$TESTPOOL/file1 /$TESTPOOL/file2
+log_must zpool sync
+
+# now four entries in the duplicate table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-duplicate: 4 entries'"
+
+# now two DDT ZAPs in the container object; DDT ZAPs aren't cleaned up until
+# the entire logical table is destroyed
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-sha256-zap- | wc -l) -eq 2
+
+# remove the files
+log_must rm -f /$TESTPOOL/file*
+log_must zpool sync
+
+# feature should move back to enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# all DDTs empty
+log_must eval "zdb -D $TESTPOOL | grep -q 'All DDTs are empty'"
+
+# logical table now destroyed; containing object destroyed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 0
+
+log_pass "basic dedup (FDT) operations work"
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_fdt_import.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_fdt_import.ksh
new file mode 100755
index 000000000000..f0f20671b95d
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_fdt_import.ksh
@@ -0,0 +1,112 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Ensure dedup retains version after import (FDT)
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "dedup (FDT) retains version after import"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with fast dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=enabled \
+    -O dedup=on \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# confirm the feature is enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-sha256"
+
+# create a file. this is four full blocks, so will produce four entries in the
+# dedup table
+log_must dd if=/dev/urandom of=/$TESTPOOL/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should now be active
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# single containing object in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 1
+obj=$(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | awk '{ print $NF }')
+
+# with only one ZAP inside
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-sha256-zap- | wc -l) -eq 1
+
+# export and import the pool
+zpool export $TESTPOOL
+zpool import $TESTPOOL
+
+# feature still active
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# remove the file
+log_must rm -f /$TESTPOOL/file1
+log_must zpool sync
+
+# feature should revert to enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# all DDTs empty
+log_must eval "zdb -D $TESTPOOL | grep -q 'All DDTs are empty'"
+
+# logical table now destroyed; containing object destroyed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 0
+
+# create a new file
+log_must dd if=/dev/urandom of=/$TESTPOOL/file2 bs=128k count=4
+log_must zpool sync
+
+# feature should be active again
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# single containing object in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 1
+obj=$(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | awk '{ print $NF }')
+
+# with only one ZAP inside
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-sha256-zap- | wc -l) -eq 1
+
+log_pass "dedup (FDT) retains version after import"
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_legacy_create.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_create.ksh
new file mode 100755
index 000000000000..e3efcf5c8b36
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_create.ksh
@@ -0,0 +1,95 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Simple test of dedup table operations (legacy)
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "basic dedup (legacy) operations work"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with legacy dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=disabled \
+    -O dedup=on \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# confirm the feature is disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-sha256"
+
+# create a file. this is four full blocks, so will produce four entries in the
+# dedup table
+log_must dd if=/dev/urandom of=/$TESTPOOL/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# should be four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# should be just one DDT ZAP in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 1
+
+# copy the file
+log_must cp /$TESTPOOL/file1 /$TESTPOOL/file2
+log_must zpool sync
+
+# now four entries in the duplicate table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-duplicate: 4 entries'"
+
+# now two DDT ZAPs in the MOS; DDT ZAPs aren't cleaned up until the entire
+# logical table is destroyed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 2
+
+# remove the files
+log_must rm -f /$TESTPOOL/file*
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# all DDTs empty
+log_must eval "zdb -D $TESTPOOL | grep -q 'All DDTs are empty'"
+
+# logical table now destroyed; all DDT ZAPs removed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 0
+
+log_pass "basic dedup (legacy) operations work"
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_mixed.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_mixed.ksh
new file mode 100755
index 000000000000..049ccaae3dca
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_mixed.ksh
@@ -0,0 +1,97 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Check legacy dedup table continues to work after pool upgrade to fast_dedup,
+# but if deleted and recreated, the new table is FDT
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "legacy and FDT dedup tables on the same pool can happily coexist"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with legacy dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=disabled \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# create two datasets, enabling a different dedup algorithm on each
+log_must zfs create -o dedup=skein $TESTPOOL/ds1
+log_must zfs create -o dedup=blake3 $TESTPOOL/ds2
+
+# confirm the feature is disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-skein"
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-blake3"
+
+# create a file in the first dataset
+log_must dd if=/dev/urandom of=/$TESTPOOL/ds1/file1 bs=128k count=4
+log_must zpool sync
+
+# should be four entries in the skein unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-skein-zap-unique: 4 entries'"
+
+# should be just one DDT ZAP in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-.*-zap- | wc -l) -eq 1
+
+# enable the fast_dedup feature
+log_must zpool set feature@fast_dedup=enabled $TESTPOOL
+
+# confirm the feature is now enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# create a file in the first dataset
+log_must dd if=/dev/urandom of=/$TESTPOOL/ds2/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should now be active
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# now also four entries in the blake3 unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-blake3-zap-unique: 4 entries'"
+
+# two entries in the MOS: the legacy skein DDT ZAP, and the containing dir for
+# the blake3 FDT table
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-.*-zap- | wc -l) -eq 1
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-blake3 | wc -l) -eq 1
+
+# containing object has one ZAP inside
+obj=$(zdb -dddd $TESTPOOL 1 | grep DDT-blake3 | awk '{ print $NF }')
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-.*-zap- | wc -l) -eq 1
+
+log_pass "legacy and FDT dedup tables on the same pool can happily coexist"
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_upgrade.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_upgrade.ksh
new file mode 100755
index 000000000000..d563fade88af
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_fdt_upgrade.ksh
@@ -0,0 +1,122 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Check legacy dedup table continues to work after pool upgrade to fast_dedup,
+# but if deleted and recreated, the new table is FDT
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "legacy dedup tables work after upgrade; new dedup tables created as FDT"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with legacy dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=disabled \
+    -O dedup=on \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# confirm the feature is disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-sha256"
+
+# create a file. this is four full blocks, so will produce four entries in the
+# dedup table
+log_must dd if=/dev/urandom of=/$TESTPOOL/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# should be four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# should be just one DDT ZAP in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 1
+
+# enable the fast_dedup feature
+log_must zpool set feature@fast_dedup=enabled $TESTPOOL
+
+# confirm the feature is now enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# copy the file
+log_must cp /$TESTPOOL/file1 /$TESTPOOL/file2
+log_must zpool sync
+
+# feature should still be enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# now four entries in the duplicate table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-duplicate: 4 entries'"
+
+# now two DDT ZAPs in the MOS; DDT ZAPs aren't cleaned up until the entire
+# logical table is destroyed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 2
+
+# remove the files
+log_must rm -f /$TESTPOOL/file*
+log_must zpool sync
+
+# feature should still be enabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "enabled"
+
+# all DDTs empty
+log_must eval "zdb -D $TESTPOOL | grep -q 'All DDTs are empty'"
+
+# logical table now destroyed; all DDT ZAPs removed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 0
+
+# create a new file
+log_must dd if=/dev/urandom of=/$TESTPOOL/file3 bs=128k count=4
+log_must zpool sync
+
+# feature should now be active
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "active"
+
+# four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# single containing object in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | wc -l) -eq 1
+obj=$(zdb -dddd $TESTPOOL 1 | grep DDT-sha256 | awk '{ print $NF }')
+
+# with one ZAP inside
+log_must test $(zdb -dddd $TESTPOOL $obj | grep DDT-sha256-zap- | wc -l) -eq 1
+
+log_pass "legacy dedup tables work after upgrade; new dedup tables created as FDT"
diff --git a/tests/zfs-tests/tests/functional/dedup/dedup_legacy_import.ksh b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_import.ksh
new file mode 100755
index 000000000000..a7b667eaf882
--- /dev/null
+++ b/tests/zfs-tests/tests/functional/dedup/dedup_legacy_import.ksh
@@ -0,0 +1,104 @@
+#!/bin/ksh -p
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or https://opensource.org/licenses/CDDL-1.0.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright (c) 2024 Klara, Inc.
+#
+
+# Ensure dedup retains version after import (legacy)
+
+. $STF_SUITE/include/libtest.shlib
+
+log_assert "dedup (legacy) retains version after import"
+
+function cleanup
+{
+	destroy_pool $TESTPOOL
+}
+
+log_onexit cleanup
+
+# create a pool with legacy dedup enabled. we disable block cloning to ensure
+# it doesn't get in the way of dedup, and we disable compression so our writes
+# create predictable results on disk
+# Use 'xattr=sa' to prevent selinux xattrs influencing our accounting
+log_must zpool create -f \
+    -o feature@fast_dedup=disabled \
+    -O dedup=on \
+    -o feature@block_cloning=disabled \
+    -O compression=off \
+    -O xattr=sa \
+    $TESTPOOL $DISKS
+
+# confirm the feature is disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# confirm there's no DDT keys in the MOS root
+log_mustnot eval "zdb -dddd $TESTPOOL 1 | grep -q DDT-sha256"
+
+# create a file. this is four full blocks, so will produce four entries in the
+# dedup table
+log_must dd if=/dev/urandom of=/$TESTPOOL/file1 bs=128k count=4
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# should be four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# should be just one DDT ZAP in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 1
+
+# export and import the pool
+zpool export $TESTPOOL
+zpool import $TESTPOOL
+
+# confirm the feature is disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# remove the file
+log_must rm -f /$TESTPOOL/file1
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# all DDTs empty
+log_must eval "zdb -D $TESTPOOL | grep -q 'All DDTs are empty'"
+
+# logical table now destroyed; all DDT ZAPs removed
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 0
+
+# create a new file
+log_must dd if=/dev/urandom of=/$TESTPOOL/file2 bs=128k count=4
+log_must zpool sync
+
+# feature should still be disabled
+log_must test $(get_pool_prop feature@fast_dedup $TESTPOOL) = "disabled"
+
+# should be four entries in the unique table
+log_must eval "zdb -D $TESTPOOL | grep -q 'DDT-sha256-zap-unique: 4 entries'"
+
+# should be just one DDT ZAP in the MOS
+log_must test $(zdb -dddd $TESTPOOL 1 | grep DDT-sha256-zap- | wc -l) -eq 1
+
+log_pass "dedup (legacy) retains version after import"
diff --git a/tests/zfs-tests/tests/functional/dedup/setup.ksh b/tests/zfs-tests/tests/functional/dedup/setup.ksh
index 3c0830401f81..a21238879faf 100755
--- a/tests/zfs-tests/tests/functional/dedup/setup.ksh
+++ b/tests/zfs-tests/tests/functional/dedup/setup.ksh
@@ -25,7 +25,3 @@
 #
 
 . $STF_SUITE/include/libtest.shlib
-
-DISK=${DISKS%% *}
-
-default_setup $DISK