diff --git a/scripts/mace.sh b/scripts/mace.sh
index 796bc18..1d6c0cc 100755
--- a/scripts/mace.sh
+++ b/scripts/mace.sh
@@ -52,7 +52,7 @@ for workload in "${workloads[@]}"; do
               --prefill-keys "${prefill_keys}" \
               --warmup-secs "${warmup_secs}" \
               --measure-secs "${measure_secs}" \
-              --shared-keyspace true \
+              --shared-keyspace \
               --read-path "${read_path}" \
               --result-file "${result_file}"
         done
diff --git a/scripts/phase1.sh b/scripts/phase1.sh
index b95f649..2b98fbf 100755
--- a/scripts/phase1.sh
+++ b/scripts/phase1.sh
@@ -84,7 +84,7 @@ run_case() {
           --prefill-keys "${prefill_keys}" \
           --warmup-secs "${warmup_secs}" \
           --measure-secs "${measure_secs}" \
-          --shared-keyspace true \
+          --shared-keyspace \
           --read-path "${read_path}" \
           --result-file "${result_file}"
     else
diff --git a/scripts/phase2.sh b/scripts/phase2.sh
index a404f77..7a0de81 100755
--- a/scripts/phase2.sh
+++ b/scripts/phase2.sh
@@ -102,7 +102,7 @@ run_case() {
           --prefill-keys "${prefill_keys}" \
           --warmup-secs "${warmup_secs}" \
           --measure-secs "${measure_secs}" \
-          --shared-keyspace true \
+          --shared-keyspace \
           --read-path "${read_path}" \
           --result-file "${result_file}"
     else
diff --git a/scripts/phase3.sh b/scripts/phase3.sh
index 35a8f1b..31b297f 100755
--- a/scripts/phase3.sh
+++ b/scripts/phase3.sh
@@ -60,7 +60,7 @@ run_case() {
           --prefill-keys "${prefill_keys}" \
           --warmup-secs "${warmup_secs}" \
           --measure-secs "${measure_secs}" \
-          --shared-keyspace true \
+          --shared-keyspace \
           --read-path "${read_path}" \
           --durability "${durability}" \
           --result-file "${result_file}"
diff --git a/scripts/phase4_soak.sh b/scripts/phase4_soak.sh
index 285cb2b..bdd1dd8 100755
--- a/scripts/phase4_soak.sh
+++ b/scripts/phase4_soak.sh
@@ -55,43 +55,149 @@ run_cmd() {
     local skip_prefill="$3"
 
     if [ "${engine}" = "mace" ]; then
-        local cleanup_flag
-        cleanup_flag="false"
-        "${root_dir}/target/release/kv_bench" \
-          --path "${db_path}" \
-          --workload "${workload}" \
-          --threads "${threads}" \
-          --key-size "${key_size}" \
-          --value-size "${value_size}" \
-          --prefill-keys "${prefill_keys}" \
-          --warmup-secs "${warmup_secs}" \
-          --measure-secs "${measure_secs}" \
-          --shared-keyspace true \
-          --read-path "${read_path}" \
-          --durability "${durability}" \
-          --cleanup "${cleanup_flag}" \
-          --reuse-path \
-          $( [ "${skip_prefill}" = "1" ] && printf '%s' "--skip-prefill" ) \
-          --result-file "${result_file}"
+        if [ "${skip_prefill}" = "1" ]; then
+            "${root_dir}/target/release/kv_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --shared-keyspace \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --reuse-path \
+              --skip-prefill \
+              --result-file "${result_file}"
+        else
+            "${root_dir}/target/release/kv_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --shared-keyspace \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --reuse-path \
+              --result-file "${result_file}"
+        fi
     else
-        "${root_dir}/rocksdb/build/release/rocksdb_bench" \
-          --path "${db_path}" \
-          --workload "${workload}" \
-          --threads "${threads}" \
-          --key-size "${key_size}" \
-          --value-size "${value_size}" \
-          --prefill-keys "${prefill_keys}" \
-          --warmup-secs "${warmup_secs}" \
-          --measure-secs "${measure_secs}" \
-          --read-path "${read_path}" \
-          --durability "${durability}" \
-          --no-cleanup \
-          --reuse-path \
-          $( [ "${skip_prefill}" = "1" ] && printf '%s' "--skip-prefill" ) \
-          --result-file "${result_file}"
+        if [ "${skip_prefill}" = "1" ]; then
+            "${root_dir}/rocksdb/build/release/rocksdb_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --no-cleanup \
+              --reuse-path \
+              --skip-prefill \
+              --result-file "${result_file}"
+        else
+            "${root_dir}/rocksdb/build/release/rocksdb_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --no-cleanup \
+              --reuse-path \
+              --result-file "${result_file}"
+        fi
     fi
 }
 
+start_run_bg() {
+    local workload="$1"
+    local measure_secs="$2"
+    local skip_prefill="$3"
+
+    if [ "${engine}" = "mace" ]; then
+        if [ "${skip_prefill}" = "1" ]; then
+            "${root_dir}/target/release/kv_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --shared-keyspace \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --reuse-path \
+              --skip-prefill \
+              --result-file "${result_file}" &
+        else
+            "${root_dir}/target/release/kv_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --shared-keyspace \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --reuse-path \
+              --result-file "${result_file}" &
+        fi
+    else
+        if [ "${skip_prefill}" = "1" ]; then
+            "${root_dir}/rocksdb/build/release/rocksdb_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --no-cleanup \
+              --reuse-path \
+              --skip-prefill \
+              --result-file "${result_file}" &
+        else
+            "${root_dir}/rocksdb/build/release/rocksdb_bench" \
+              --path "${db_path}" \
+              --workload "${workload}" \
+              --threads "${threads}" \
+              --key-size "${key_size}" \
+              --value-size "${value_size}" \
+              --prefill-keys "${prefill_keys}" \
+              --warmup-secs "${warmup_secs}" \
+              --measure-secs "${measure_secs}" \
+              --read-path "${read_path}" \
+              --durability "${durability}" \
+              --no-cleanup \
+              --reuse-path \
+              --result-file "${result_file}" &
+        fi
+    fi
+    runner_pid=$!
+}
+
 if [ ! -f "${restart_file}" ]; then
     printf "cycle,start_epoch,kill_sent,worker_exit,restart_status,restart_ready_ms\n" > "${restart_file}"
 fi
@@ -107,8 +213,7 @@ while [ "$(date +%s)" -lt "${end_epoch}" ]; do
     printf "[phase4][%s] cycle=%s start=%s\n" "${engine}" "${cycle}" "${cycle_start}"
 
     # long run in background; kill after interval
-    (run_cmd "${workload_main}" "${run_measure_secs}" 1) &
-    runner_pid=$!
+    start_run_bg "${workload_main}" "${run_measure_secs}" 1
 
     sleep "${crash_interval_secs}"