HDDS-12239. Volume should not be marked as unhealthy when disk full

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/volume/StorageVolume.java

@@ -614,6 +614,15 @@ public synchronized VolumeCheckResult check(@Nullable Boolean unused)
       return VolumeCheckResult.HEALTHY;
     }
 
+    // At least some space required to check disk read/write
+    // If there are not enough space remaining,
+    // to avoid volume failure we can ignore checking disk read/write
+    int hundredMB = 100 * 1024 * 1024;
+    int minimumDiskSpace = Math.max(healthCheckFileSize * 10, hundredMB);
+    if (volumeInfo.get().getCurrentUsage().getAvailable() < minimumDiskSpace) {
+      return VolumeCheckResult.HEALTHY;
+    }
+
     // Since IO errors may be intermittent, volume remains healthy until the
     // threshold of failures is crossed.
     boolean diskChecksPassed = DiskCheckUtil.checkReadWrite(storageDir,
@@ -625,6 +634,13 @@ public synchronized VolumeCheckResult check(@Nullable Boolean unused)
           " interrupted.");
     }
 
+    // As WRITE keeps happening there is probability, disk has become full during above check.
+    // We can check again if disk is full. If it is full,
+    // in this case keep volume as healthy so that READ can still be served
+    if (!diskChecksPassed && volumeInfo.get().getCurrentUsage().getAvailable() < minimumDiskSpace) {
+      return VolumeCheckResult.HEALTHY;
+    }
+
     // Move the sliding window of IO test results forward 1 by adding the
     // latest entry and removing the oldest entry from the window.
     // Update the failure counter for the new window.

hadoop-hdds/container-service/src/test/java/org/apache/hadoop/ozone/container/common/volume/TestStorageVolumeHealthChecks.java

@@ -110,6 +110,39 @@ public boolean checkExistence(File storageDir) {
     assertEquals(VolumeCheckResult.FAILED, result);
   }
 
+  @ParameterizedTest
+  @MethodSource("volumeBuilders")
+  public void testVolumeFullHealth(StorageVolume.Builder<?> builder)
+      throws Exception {
+    StorageVolume volume = builder.build();
+
+    VolumeUsage usage = volume.getVolumeInfo().get().getUsageForTesting();
+    int hundredMB = 100 * 1024 * 1024;
+    // Keep remaining space as just less than 100 MB
+    usage.incrementUsedSpace(usage.getCurrentUsage().getAvailable() - hundredMB + 1);
+    usage.realUsage();
+    DiskCheckUtil.DiskChecks ioFailure = new DiskCheckUtil.DiskChecks() {
+      @Override
+      public boolean checkReadWrite(File storageDir, File testFileDir,
+                                    int numBytesToWrite) {
+        return false;
+      }
+    };
+    DiskCheckUtil.setTestImpl(ioFailure);
+    // Volume will remain healthy as volume don't have enough space to check READ/WRITE
+    assertEquals(VolumeCheckResult.HEALTHY, volume.check(false));
+    // Even in second try volume will remain HEALTHY
+    assertEquals(VolumeCheckResult.HEALTHY, volume.check(false));
+
+    // Now keep enough space for read/write check to go through
+    usage.decrementUsedSpace(hundredMB + 1);
+
+    // volumeIOFailureTolerance is 1, so first time it will be HEALTHY
+    assertEquals(VolumeCheckResult.HEALTHY, volume.check(false));
+    // second time volume will fail as READ/WRITE check has failed
+    assertEquals(VolumeCheckResult.FAILED, volume.check(false));
+  }
+
   @ParameterizedTest
   @MethodSource("volumeBuilders")
   public void testCheckPermissions(StorageVolume.Builder<?> builder)