diff --git a/plugins/nf-float/src/main/com/memverge/nextflow/FloatConf.groovy b/plugins/nf-float/src/main/com/memverge/nextflow/FloatConf.groovy
index 7159c64..d8be188 100644
--- a/plugins/nf-float/src/main/com/memverge/nextflow/FloatConf.groovy
+++ b/plugins/nf-float/src/main/com/memverge/nextflow/FloatConf.groovy
@@ -40,6 +40,7 @@ class FloatConf {
     static final String NF_TASK_NAME = 'nextflow-io-task-name'
     static final String FLOAT_INPUT_SIZE = 'input-size'
     static final String FLOAT_JOB_KIND = 'job-kind'
+    static final long MIN_VOL_SIZE = 6
     static final int DFT_MAX_CPU_FACTOR = 4
     static final int DFT_MAX_MEM_FACTOR = 4
 
diff --git a/plugins/nf-float/src/main/com/memverge/nextflow/FloatGridExecutor.groovy b/plugins/nf-float/src/main/com/memverge/nextflow/FloatGridExecutor.groovy
index 7ccc0e2..3ef71f8 100644
--- a/plugins/nf-float/src/main/com/memverge/nextflow/FloatGridExecutor.groovy
+++ b/plugins/nf-float/src/main/com/memverge/nextflow/FloatGridExecutor.groovy
@@ -40,7 +40,6 @@ import java.nio.file.StandardCopyOption
 class FloatGridExecutor extends AbstractGridExecutor {
     private static final int DFT_MEM_GB = 1
     private static final long FUSION_MIN_VOL_SIZE = 80
-    private static final long MIN_VOL_SIZE = 40
     private static final long DISK_INPUT_FACTOR = 5
 
     private FloatJobs _floatJobs
@@ -403,8 +402,8 @@ class FloatGridExecutor extends AbstractGridExecutor {
         return cmd
     }
 
-    private void addVolSize(List<String> cmd, TaskRun task) {
-        long size = MIN_VOL_SIZE
+    void addVolSize(List<String> cmd, TaskRun task) {
+        long size = FloatConf.MIN_VOL_SIZE
 
         def disk = task.config.getDisk()
         if (disk) {
@@ -413,9 +412,11 @@ class FloatGridExecutor extends AbstractGridExecutor {
         if (isFusionEnabled()) {
             size = Math.max(size, FUSION_MIN_VOL_SIZE)
         }
-        long inputSizeGB =  (long)(getInputFileSize(task) / 1024 / 1024 / 1024)
-        long minDiskSizeBasedOnInput = inputSizeGB * DISK_INPUT_FACTOR
-        size = Math.max(size, minDiskSizeBasedOnInput)
+        if (task.scratch) {
+            double inputSizeGB =  (double)(getInputFileSize(task)) / 1024 / 1024 / 1024
+            long minDiskSizeBasedOnInput = Math.round(inputSizeGB * DISK_INPUT_FACTOR)
+            size = Math.max(size, minDiskSizeBasedOnInput)
+        }
         cmd << '--imageVolSize' << size.toString()
     }
 
diff --git a/plugins/nf-float/src/test/com/memverge/nextflow/FloatBaseTest.groovy b/plugins/nf-float/src/test/com/memverge/nextflow/FloatBaseTest.groovy
index 200db36..cfc58a8 100644
--- a/plugins/nf-float/src/test/com/memverge/nextflow/FloatBaseTest.groovy
+++ b/plugins/nf-float/src/test/com/memverge/nextflow/FloatBaseTest.groovy
@@ -122,6 +122,6 @@ class FloatBaseTest extends BaseTest {
                 '--customTag', "${FloatConf.NF_TASK_NAME}:foo--$taskIDStr-",
                 '--customTag', "${FloatConf.FLOAT_INPUT_SIZE}:0",
                 '--customTag', "${FloatConf.NF_RUN_NAME}:test-run",
-                '--imageVolSize', '40']
+                '--imageVolSize', FloatConf.MIN_VOL_SIZE]
     }
 }
diff --git a/plugins/nf-float/src/test/com/memverge/nextflow/FloatGridExecutorTest.groovy b/plugins/nf-float/src/test/com/memverge/nextflow/FloatGridExecutorTest.groovy
index 6de3d9c..302d26c 100644
--- a/plugins/nf-float/src/test/com/memverge/nextflow/FloatGridExecutorTest.groovy
+++ b/plugins/nf-float/src/test/com/memverge/nextflow/FloatGridExecutorTest.groovy
@@ -78,7 +78,7 @@ class FloatGridExecutorTest extends FloatBaseTest {
         given:
         final exec = newTestExecutor()
         exec.floatJobs.updateJob(FloatJob.parse(
-            """
+                """
                   id: a
                   customTags:
                       nf-job-id: tJob-1
@@ -211,7 +211,7 @@ class FloatGridExecutorTest extends FloatBaseTest {
                 '10']
 
         then:
-        cmd  == expected
+        cmd.join(' ') == expected.join(' ')
     }
 
     def "add specific extras"() {
@@ -421,10 +421,10 @@ class FloatGridExecutorTest extends FloatBaseTest {
     def "use time directive"() {
         given:
         final exec = newTestExecutor([
-                float: [address: addr,
-                        username: user,
-                        password: pass,
-                        nfs: nfs,
+                float: [address         : addr,
+                        username        : user,
+                        password        : pass,
+                        nfs             : nfs,
                         ignoreTimeFactor: false]
         ])
         final task = newTask(exec, 0, new TaskConfig(
@@ -442,12 +442,12 @@ class FloatGridExecutorTest extends FloatBaseTest {
     def "use timeout factor"() {
         given:
         final exec = newTestExecutor(
-                [float: [address   : addr,
-                         username  : user,
-                         password  : pass,
-                         nfs       : nfs,
+                [float: [address         : addr,
+                         username        : user,
+                         password        : pass,
+                         nfs             : nfs,
                          ignoreTimeFactor: false,
-                         timeFactor: 1.1]])
+                         timeFactor      : 1.1]])
         final task = newTask(exec, 0, new TaskConfig(
                 container: image,
                 time: '1h',
@@ -629,7 +629,7 @@ class FloatGridExecutorTest extends FloatBaseTest {
         when:
         final count = taskMap.size()
         // update a list of the task status
-        for ( def entry : taskMap.entrySet()) {
+        for (def entry : taskMap.entrySet()) {
             exec.floatJobs.updateJob(FloatJob.parse(taskStatus(entry.key, entry.value)))
         }
         def res = exec.parseQueueStatus("")
@@ -692,4 +692,43 @@ class FloatGridExecutorTest extends FloatBaseTest {
         setEnv('MMC_USERNAME')
         setEnv('MMC_PASSWORD')
     }
+
+    def "get disk size when scratch is not enabled"() {
+        given:
+        final exec = newTestExecutor()
+        final task = newTask(exec, 0)
+
+        when:
+        List<String> cmd = []
+        exec.addVolSize(cmd, task)
+
+        then:
+        cmd.join(' ') == "--imageVolSize ${FloatConf.MIN_VOL_SIZE}"
+    }
+
+    def "get disk size when specified in task"() {
+        given:
+        final exec = newTestExecutor()
+        final task = newTask(exec, 0, new TaskConfig(disk: '18.GB'))
+
+        when:
+        List<String> cmd = []
+        exec.addVolSize(cmd, task)
+
+        then:
+        cmd.join(' ') == "--imageVolSize 18"
+    }
+
+    def "get disk size when specified size is smaller than min"() {
+        given:
+        final exec = newTestExecutor()
+        final task = newTask(exec, 0, new TaskConfig(disk: '2.GB'))
+
+        when:
+        List<String> cmd = []
+        exec.addVolSize(cmd, task)
+
+        then:
+        cmd.join(' ') == "--imageVolSize ${FloatConf.MIN_VOL_SIZE}"
+    }
 }