diff --git a/src/common/pool_map.c b/src/common/pool_map.c
index c932ae67f6c..358f8dfb5e7 100644
--- a/src/common/pool_map.c
+++ b/src/common/pool_map.c
@@ -423,18 +423,19 @@ pool_buf_attach(struct pool_buf *buf, struct pool_component *comps,
 			return -DER_INVAL;
 		}
 
+		D_DEBUG(DB_TRACE, "nr %d %s\n", nr, pool_comp_type2str(comps[0].co_type));
+
 		if (comps[0].co_type == PO_COMP_TP_TARGET)
 			buf->pb_target_nr++;
 		else if (comps[0].co_type == PO_COMP_TP_RANK)
 			buf->pb_node_nr++;
-		else
+		else {
 			buf->pb_domain_nr++;
+			D_ERROR("pb_domain_nr=%u\n", buf->pb_domain_nr);
+		}
 
 		buf->pb_comps[nr] = comps[0];
 		buf->pb_comps[nr].co_flags &= ~PO_COMPF_CHK_DONE;
-
-		D_DEBUG(DB_TRACE, "nr %d %s\n", nr,
-			pool_comp_type2str(comps[0].co_type));
 	}
 	return 0;
 }
@@ -1531,11 +1532,13 @@ add_domain_tree_to_pool_buf(struct pool_map *map, struct pool_buf *map_buf, int
 		return rc;
 
 	/* discard the root - it's being added to the pool buf elsewhere */
+	D_ERROR("ndomains=%u\n", ndomains);
 	rc = d_fd_tree_next(&tree, &node);
 	while (rc == 0) {
 		struct pool_component map_comp = {0};
 
 		rc = d_fd_tree_next(&tree, &node);
+		D_ERROR("d_fd_tree_next() -> rc=%d\n", rc);
 		if (rc != 0) {
 			/* got to the end of the tree with no problems */
 			if (rc == -DER_NONEXIST)
@@ -1628,7 +1631,9 @@ add_domain_tree_to_pool_buf(struct pool_map *map, struct pool_buf *map_buf, int
 			map_comp.co_ver, map_comp.co_in_ver, map_comp.co_fseq, map_comp.co_flags,
 			map_comp.co_nr);
 
+		D_ERROR("add_domain_tree_to_pool_buf -> pool_buf_attach() call\n");
 		rc = pool_buf_attach(map_buf, &map_comp, 1);
+		D_ERROR("pb_domain_nr=%u\n", map_buf->pb_domain_nr);
 		if (rc != 0)
 			D_ERROR("failed attaching component ID %u to pool buf\n", map_comp.co_id);
 	}
@@ -1688,6 +1693,7 @@ gen_pool_buf(struct pool_map *map, struct pool_buf **map_buf_out, int map_versio
 		D_ERROR("failed to calculate number of domains, "DF_RC"\n", DP_RC(rc));
 		return rc;
 	}
+	D_ERROR("num_domain_comps=%u\n", num_domain_comps);
 	D_ASSERT(num_domain_comps > 0);
 	num_domain_comps--; /* remove the root domain - allocated separately */
 
diff --git a/src/control/fault/code/codes.go b/src/control/fault/code/codes.go
index bb07f0b89ed..f6e7800a49e 100644
--- a/src/control/fault/code/codes.go
+++ b/src/control/fault/code/codes.go
@@ -161,6 +161,7 @@ const (
 	ServerPoolHasContainers
 	ServerPoolMemRatioNoRoles
 	ServerBadFaultDomainLabels
+	ServerPoolTooFewFaultDomains
 	ServerJoinReplaceEnabledPoolRank
 	ServerRankAdminExcluded
 	ServerTransparentHugepageEnabled
diff --git a/src/control/run.sh b/src/control/run.sh
new file mode 100755
index 00000000000..7860b65440b
--- /dev/null
+++ b/src/control/run.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+
+export LD_LIBRARY_PATH='/opt/daos/lib:/opt/daos/lib64:/opt/daos/lib64/daos_srv:/opt/daos/prereq/debug/mercury/lib:/opt/daos/prereq/debug/spdk/lib64/daos_srv:/opt/daos/prereq/debug/ofi/lib'
+export CGO_LDFLAGS='-L/opt/daos/lib -L/opt/daos/lib64 -L/opt/daos/lib64/daos_srv -L/home/michalsk/work/daos-stack/daos/build/debug/gcc/src/control/lib/spdk -L/opt/daos/prereq/debug/mercury/lib -L/opt/daos/prereq/debug/spdk/lib64/daos_srv -L/opt/daos/prereq/debug/ofi/lib'
+export CGO_CFLAGS='-I/opt/daos/include -I/opt/daos/prereq/debug/mercury/include -I/opt/daos/prereq/debug/spdk/include/daos_srv -I/opt/daos/prereq/debug/ofi/include -I/opt/daos/prereq/debug/argobots/include -I/home/michalsk/work/daos-stack/daos/src/include'
+
+/usr/local/go/bin/go test -v ./system/ -run TestSystem_Membership_CompressedFaultDomainTree
diff --git a/src/control/server/faults.go b/src/control/server/faults.go
index a2e51760026..4359d06f1a6 100644
--- a/src/control/server/faults.go
+++ b/src/control/server/faults.go
@@ -1,6 +1,6 @@
 //
 // (C) Copyright 2020-2024 Intel Corporation.
-// (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+// (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
 //
 // SPDX-License-Identifier: BSD-2-Clause-Patent
 //
@@ -174,6 +174,15 @@ var FaultPoolMemRatioNoRoles = serverFault(
 	"either remove MD-on-SSD-specific options from the command request or set bdev_roles in "+
 		"server config file to enable MD-on-SSD")
 
+func FaultPoolTooFewFaultDomains(rdFac int, numDomains int) *fault.Fault {
+	return serverFault(
+		code.ServerPoolTooFewFaultDomains,
+		fmt.Sprintf("pool redundancy factor %d requires at least %d fault domains but only %d are available",
+			rdFac, rdFac+1, numDomains),
+		"retry the request with a lower redundancy factor or add more fault domains",
+	)
+}
+
 func FaultBadFaultDomainLabels(faultPath, addr string, reqLabels, systemLabels []string) *fault.Fault {
 	return serverFault(
 		code.ServerBadFaultDomainLabels,
diff --git a/src/control/server/mgmt_pool.go b/src/control/server/mgmt_pool.go
index dbe5f0d5ae9..6919af3da92 100644
--- a/src/control/server/mgmt_pool.go
+++ b/src/control/server/mgmt_pool.go
@@ -1,6 +1,6 @@
 //
 // (C) Copyright 2020-2024 Intel Corporation.
-// (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+// (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
 //
 // SPDX-License-Identifier: BSD-2-Clause-Patent
 //
@@ -414,6 +414,28 @@ func (svc *mgmtSvc) poolCreate(parent context.Context, req *mgmtpb.PoolCreateReq
 		return nil, FaultPoolInvalidServiceReps(maxSvcReps)
 	}
 
+	// Check if the requested redundancy factor can be met with the number of supplied fault domains.
+	domainNr, err := svc.membership.DomainNr(svc.log, req.Ranks...)
+	if err != nil {
+		return nil, err
+	}
+	// instances := svc.harness.Instances()
+	// if len(instances) < 1 {
+	// 	return nil, errors.New("harness has no managed instances")
+	// }
+	// domainNr := rankNr * instances[0].GetTargetCount()
+	// svc.log.Errorf("rankNr %d, target count %d, domainNr %d", rankNr, instances[0].GetTargetCount(), domainNr)
+	for _, prop := range req.GetProperties() {
+		if prop.GetNumber() == uint32(daos.PoolPropertyRedunFac) {
+			rdFac := int(prop.GetNumval())
+			if rdFac+1 > domainNr {
+				return nil, FaultPoolTooFewFaultDomains(rdFac, domainNr)
+			}
+			svc.log.Errorf("rdFac %d does NOT exceed available fault domains %d", rdFac, domainNr)
+			break
+		}
+	}
+
 	// IO engine needs the fault domain tree for placement purposes
 	req.FaultDomains, err = svc.membership.CompressedFaultDomainTree(req.Ranks...)
 	if err != nil {
diff --git a/src/control/server/mgmt_pool_test.go b/src/control/server/mgmt_pool_test.go
index 51a3bdc2813..13035d89ba5 100644
--- a/src/control/server/mgmt_pool_test.go
+++ b/src/control/server/mgmt_pool_test.go
@@ -1,6 +1,6 @@
 //
 // (C) Copyright 2020-2024 Intel Corporation.
-// (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+// (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
 //
 // SPDX-License-Identifier: BSD-2-Clause-Patent
 //
@@ -118,6 +118,23 @@ func testPoolLabelProp() []*mgmtpb.PoolProperty {
 	}
 }
 
+func testPoolRedunFacProp() []*mgmtpb.PoolProperty {
+	return []*mgmtpb.PoolProperty{
+		{
+			Number: daos.PoolPropertyLabel,
+			Value: &mgmtpb.PoolProperty_Strval{
+				Strval: "test",
+			},
+		},
+		{
+			Number: daos.PoolPropertyRedunFac,
+			Value: &mgmtpb.PoolProperty_Numval{
+				Numval: 1,
+			},
+		},
+	}
+}
+
 func TestServer_MgmtSvc_PoolCreateAlreadyExists(t *testing.T) {
 	for name, tc := range map[string]struct {
 		state     system.PoolServiceState
@@ -635,6 +652,33 @@ func TestServer_MgmtSvc_PoolCreate(t *testing.T) {
 			},
 			expErr: FaultPoolNoLabel,
 		},
+		"failed creation too few fault domains": {
+			targetCount: 1,
+			req: &mgmtpb.PoolCreateReq{
+				Uuid:       test.MockUUID(1),
+				TierBytes:  []uint64{100 * humanize.GiByte, 10 * humanize.TByte},
+				Ranks:      []uint32{0},
+				Properties: testPoolRedunFacProp(),
+			},
+			expErr: FaultPoolTooFewFaultDomains(1, 2),
+		},
+		"successful creation with rd_fac": {
+			targetCount: 2,
+			req: &mgmtpb.PoolCreateReq{
+				Uuid:       test.MockUUID(1),
+				TierBytes:  []uint64{100 * humanize.GiByte, 10 * humanize.TByte},
+				Ranks:      []uint32{0, 1},
+				Properties: testPoolRedunFacProp(),
+			},
+			drpcRet: &mgmtpb.PoolCreateResp{
+				TierBytes: []uint64{100 * humanize.GiByte, 10 * humanize.TByte},
+				TgtRanks:  []uint32{0, 1},
+			},
+			expResp: &mgmtpb.PoolCreateResp{
+				TierBytes: []uint64{100 * humanize.GiByte, 10 * humanize.TByte},
+				TgtRanks:  []uint32{0, 1},
+			},
+		},
 	} {
 		t.Run(name, func(t *testing.T) {
 			buf.Reset()
diff --git a/src/control/system/membership.go b/src/control/system/membership.go
index 691243c0682..631b66594b4 100644
--- a/src/control/system/membership.go
+++ b/src/control/system/membership.go
@@ -785,6 +785,55 @@ func (m *Membership) CompressedFaultDomainTree(ranks ...uint32) ([]uint32, error
 	return append([]uint32{md}, compressTree(subtree)...), nil
 }
 
+func printFaultDomainTree(log logging.Logger, tree *FaultDomainTree, prefix string) {
+	log.Debugf("%s [%d] %s", prefix, tree.ID, tree.Domain.String())
+	for _, child := range tree.Children {
+		printFaultDomainTree(log, child, prefix+"-")
+	}
+}
+
+func (m *Membership) DomainNr(log logging.Logger, ranks ...uint32) (int, error) {
+	tree := m.db.FaultDomainTree()
+	if tree == nil {
+		return 0, errors.New("uninitialized fault domain tree")
+	}
+
+	subtree, err := getFaultDomainSubtree(tree, ranks...)
+	if err != nil {
+		return 0, err
+	}
+
+	log.Debugf("Fault domain tree (depth=%d):", subtree.Depth())
+	printFaultDomainTree(log, subtree, "")
+
+	// TODO DAOS-6353: Properly detect when fault and perf domain are requested.
+	// Currently any depth greater than the minimum must indicate a performance domain.
+	minDepth := 2 // domain + rank
+	if tree.Depth() > minDepth {
+		// Loop over the children of the root and sum up the number their children.
+		sum := 0
+		for _, child := range subtree.Children {
+			sum += len(child.Children)
+		}
+		return sum, nil
+	} else {
+		// There are no perf domains, so all children of the root are fault domains.
+		return len(subtree.Children), nil
+	}
+
+	// log.Debugf("ndomains=%d", len(subtree.Domains()))
+
+	// nr := 0
+	// for i, domain := range subtree.Domains() {
+	// 	if rank, isRank := getFaultDomainRank(domain); isRank {
+	// 		log.Debugf("domain[%d] = rank %d", i, rank)
+	// 		nr++
+	// 	}
+	// }
+
+	return len(subtree.Domains()), nil
+}
+
 const (
 	DomTreeMetadataHasFaultDom uint32 = (1 << iota)
 	DomTreeMetadataHasPerfDom
diff --git a/src/control/system/membership_test.go b/src/control/system/membership_test.go
index 7d3e2db8473..81d6668b17b 100644
--- a/src/control/system/membership_test.go
+++ b/src/control/system/membership_test.go
@@ -1299,10 +1299,11 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 	}
 
 	for name, tc := range map[string]struct {
-		tree       *FaultDomainTree
-		inputRanks []uint32
-		expResult  []uint32
-		expErr     error
+		tree        *FaultDomainTree
+		inputRanks  []uint32
+		expResult   []uint32
+		expErr      error
+		expDomainNr int
 	}{
 		"nil tree": {
 			expErr: errors.New("uninitialized fault domain tree"),
@@ -1315,6 +1316,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				ExpFaultDomainID(0),
 				0,
 			},
+			expDomainNr: 0,
 		},
 		"single branch, no rank leaves": {
 			tree: NewFaultDomainTree(
@@ -1335,6 +1337,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				ExpFaultDomainID(3),
 				0,
 			},
+			expDomainNr: 1,
 		},
 		"multi branch, no rank leaves": {
 			tree: NewFaultDomainTree(
@@ -1374,6 +1377,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				ExpFaultDomainID(8),
 				0,
 			},
+			expDomainNr: 5,
 		},
 		"single branch with rank leaves": {
 			tree: NewFaultDomainTree(
@@ -1395,6 +1399,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				1,
 				5,
 			},
+			expDomainNr: 1,
 		},
 		"multi branch with rank leaves": {
 			tree: NewFaultDomainTree(
@@ -1442,6 +1447,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				4,
 				5,
 			},
+			expDomainNr: 6,
 		},
 		"intermediate domain has name like rank": {
 			tree: NewFaultDomainTree(
@@ -1463,6 +1469,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				1,
 				1, // rank
 			},
+			expDomainNr: 1,
 		},
 		"request one rank with node only": {
 			tree: NewFaultDomainTree(
@@ -1485,6 +1492,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				// ranks
 				4,
 			},
+			expDomainNr: 1,
 		},
 		"request one rank": {
 			tree: NewFaultDomainTree(
@@ -1510,6 +1518,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				// ranks
 				4,
 			},
+			expDomainNr: 1,
 		},
 		"request multiple ranks": {
 			tree: NewFaultDomainTree(
@@ -1550,6 +1559,7 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 				4,
 				5,
 			},
+			expDomainNr: 4,
 		},
 		"request nonexistent rank": {
 			tree: NewFaultDomainTree(
@@ -1572,12 +1582,15 @@ func TestSystem_Membership_CompressedFaultDomainTree(t *testing.T) {
 			membership := NewMembership(log, db)
 
 			result, err := membership.CompressedFaultDomainTree(tc.inputRanks...)
-
 			test.CmpErr(t, tc.expErr, err)
 
 			if diff := cmp.Diff(tc.expResult, result); diff != "" {
 				t.Fatalf("(-want, +got): %s", diff)
 			}
+
+			domainNr, err := membership.DomainNr(log, tc.inputRanks...)
+			test.CmpErr(t, tc.expErr, err)
+			test.AssertEqual(t, tc.expDomainNr, domainNr, "unexpected domain number")
 		})
 	}
 }
diff --git a/src/pool/srv_pool.c b/src/pool/srv_pool.c
index fad6ef2ea25..54a1a3f8f89 100644
--- a/src/pool/srv_pool.c
+++ b/src/pool/srv_pool.c
@@ -809,6 +809,8 @@ init_pool_metadata(struct rdb_tx *tx, const rdb_path_t *kvs, uint32_t nnodes, co
 		D_GOTO(out_prop, rc);
 	}
 
+	D_ERROR("===\n");
+	D_ERROR("ndomains=%u\n", ndomains);
 	rc = gen_pool_buf(NULL /* map */, &map_buf, map_version, ndomains, nnodes, ntargets,
 			  domains, dss_tgt_nr);
 	if (rc != 0) {
@@ -822,6 +824,7 @@ init_pool_metadata(struct rdb_tx *tx, const rdb_path_t *kvs, uint32_t nnodes, co
 		if (entry->dpe_val + 1 > map_buf->pb_domain_nr) {
 			D_ERROR("ndomains(%u) could not meet specified redunc factor(%lu)\n",
 				map_buf->pb_domain_nr, entry->dpe_val);
+			D_ERROR("===\n");
 			D_GOTO(out_map_buf, rc = -DER_INVAL);
 		}
 	} else {
diff --git a/src/tests/ftest/performance/ior_easy.yaml b/src/tests/ftest/performance/ior_easy.yaml
index 139f199f53e..34b95ffb0be 100644
--- a/src/tests/ftest/performance/ior_easy.yaml
+++ b/src/tests/ftest/performance/ior_easy.yaml
@@ -24,7 +24,7 @@ server_config:
 
 pool:
   size: 95%
-  properties: rd_fac:0,space_rb:0,ec_cell_sz:1MiB
+  properties: rd_fac:3,space_rb:0,ec_cell_sz:1MiB
 
 container:
   type: POSIX