Do not select zones with <5% free after upload (#9877)

Looking into full disk errors on zoned setup. We don't take the
5% space requirement into account when selecting a zone.

The interesting part is that even considering this we don't
know the size of the object the user wants to upload when
they do multipart uploads.

It seems quite defensive to always upload multiparts to
the zone where there is the most space since all load will
be directed to a part of the cluster.

In these cases we make sure it can at least hold a 1GiB file
and we disadvantage fuller zones more by subtracting the
expected size before weighing.

cmd/erasure-zones.go

@@ -103,12 +103,13 @@ func (p zonesAvailableSpace) TotalAvailable() uint64 {
 	return total
 }
 
-func (z *erasureZones) getAvailableZoneIdx(ctx context.Context) int {
-	zones := z.getZonesAvailableSpace(ctx)
+// getAvailableZoneIdx will return an index that can hold size bytes.
+// -1 is returned if no zones have available space for the size given.
+func (z *erasureZones) getAvailableZoneIdx(ctx context.Context, size int64) int {
+	zones := z.getZonesAvailableSpace(ctx, size)
 	total := zones.TotalAvailable()
 	if total == 0 {
-		// Houston, we have a problem, maybe panic??
-		return zones[0].Index
+		return -1
 	}
 	// choose when we reach this many
 	choose := rand.Uint64() % total
@@ -120,10 +121,17 @@ func (z *erasureZones) getAvailableZoneIdx(ctx context.Context) int {
 		}
 	}
 	// Should not happen, but print values just in case.
-	panic(fmt.Errorf("reached end of zones (total: %v, atTotal: %v, choose: %v)", total, atTotal, choose))
+	logger.LogIf(ctx, fmt.Errorf("reached end of zones (total: %v, atTotal: %v, choose: %v)", total, atTotal, choose))
+	return -1
 }
 
-func (z *erasureZones) getZonesAvailableSpace(ctx context.Context) zonesAvailableSpace {
+// getZonesAvailableSpace will return the available space of each zone after storing the content.
+// If there is not enough space the zone will return 0 bytes available.
+// Negative sizes are seen as 0 bytes.
+func (z *erasureZones) getZonesAvailableSpace(ctx context.Context, size int64) zonesAvailableSpace {
+	if size < 0 {
+		size = 0
+	}
 	var zones = make(zonesAvailableSpace, len(z.zones))
 
 	storageInfos := make([]StorageInfo, len(z.zones))
@@ -144,6 +152,24 @@ func (z *erasureZones) getZonesAvailableSpace(ctx context.Context) zonesAvailabl
 		for _, davailable := range zinfo.Available {
 			available += davailable
 		}
+		var total uint64
+		for _, dtotal := range zinfo.Total {
+			total += dtotal
+		}
+		// Make sure we can fit "size" on to the disk without getting above the diskFillFraction
+		if available < uint64(size) {
+			available = 0
+		}
+		if available > 0 {
+			// How much will be left after adding the file.
+			available -= -uint64(size)
+
+			// wantLeft is how much space there at least must be left.
+			wantLeft := uint64(float64(total) * (1.0 - diskFillFraction))
+			if available <= wantLeft {
+				available = 0
+			}
+		}
 		zones[i] = zoneAvailableSpace{
 			Index:     i,
 			Available: available,
@@ -154,7 +180,7 @@ func (z *erasureZones) getZonesAvailableSpace(ctx context.Context) zonesAvailabl
 
 // getZoneIdx returns the found previous object and its corresponding zone idx,
 // if none are found falls back to most available space zone.
-func (z *erasureZones) getZoneIdx(ctx context.Context, bucket, object string, opts ObjectOptions) (idx int, err error) {
+func (z *erasureZones) getZoneIdx(ctx context.Context, bucket, object string, opts ObjectOptions, size int64) (idx int, err error) {
 	if z.SingleZone() {
 		return 0, nil
 	}
@@ -179,7 +205,13 @@ func (z *erasureZones) getZoneIdx(ctx context.Context, bucket, object string, op
 		// Success case and when DeleteMarker is true return.
 		return i, nil
 	}
-	return z.getAvailableZoneIdx(ctx), nil
+
+	// We multiply the size by 2 to account for erasure coding.
+	idx = z.getAvailableZoneIdx(ctx, size*2)
+	if idx < 0 {
+		return -1, toObjectErr(errDiskFull)
+	}
+	return idx, nil
 }
 
 func (z *erasureZones) Shutdown(ctx context.Context) error {
@@ -508,7 +540,7 @@ func (z *erasureZones) PutObject(ctx context.Context, bucket string, object stri
 		return z.zones[0].PutObject(ctx, bucket, object, data, opts)
 	}
 
-	idx, err := z.getZoneIdx(ctx, bucket, object, opts)
+	idx, err := z.getZoneIdx(ctx, bucket, object, opts, data.Size())
 	if err != nil {
 		return ObjectInfo{}, err
 	}
@@ -590,7 +622,7 @@ func (z *erasureZones) CopyObject(ctx context.Context, srcBucket, srcObject, dst
 		return z.zones[0].CopyObject(ctx, srcBucket, srcObject, dstBucket, dstObject, srcInfo, srcOpts, dstOpts)
 	}
 
-	zoneIdx, err := z.getZoneIdx(ctx, dstBucket, dstObject, dstOpts)
+	zoneIdx, err := z.getZoneIdx(ctx, dstBucket, dstObject, dstOpts, srcInfo.Size)
 	if err != nil {
 		return objInfo, err
 	}
@@ -1310,7 +1342,8 @@ func (z *erasureZones) NewMultipartUpload(ctx context.Context, bucket, object st
 		return z.zones[0].NewMultipartUpload(ctx, bucket, object, opts)
 	}
 
-	idx, err := z.getZoneIdx(ctx, bucket, object, opts)
+	// We don't know the exact size, so we ask for at least 1GiB file.
+	idx, err := z.getZoneIdx(ctx, bucket, object, opts, 1<<30)
 	if err != nil {
 		return "", err
 	}

cmd/globals.go

@@ -96,6 +96,9 @@ const (
 
 	// Maximum size of default bucket encryption configuration allowed
 	maxBucketSSEConfigSize = 1 * humanize.MiByte
+
+	// diskFillFraction is the fraction of a disk we allow to be filled.
+	diskFillFraction = 0.95
 )
 
 var globalCLIContext = struct {

cmd/xl-storage.go

@@ -288,7 +288,7 @@ var ignoreDiskFreeOS = []string{
 func checkDiskMinTotal(di disk.Info) (err error) {
 	// Remove 5% from total space for cumulative disk space
 	// used for journalling, inodes etc.
-	totalDiskSpace := float64(di.Total) * 0.95
+	totalDiskSpace := float64(di.Total) * diskFillFraction
 	if int64(totalDiskSpace) <= diskMinTotalSpace {
 		return errMinDiskSize
 	}
@@ -298,7 +298,7 @@ func checkDiskMinTotal(di disk.Info) (err error) {
 // check if disk free has minimum required size.
 func checkDiskMinFree(di disk.Info) error {
 	// Remove 5% from free space for cumulative disk space used for journalling, inodes etc.
-	availableDiskSpace := float64(di.Free) * 0.95
+	availableDiskSpace := float64(di.Free) * diskFillFraction
 	if int64(availableDiskSpace) <= diskMinFreeSpace {
 		return errDiskFull
 	}
@@ -328,7 +328,7 @@ func checkDiskFree(diskPath string, neededSpace int64) (err error) {
 	}
 
 	// Check if we have enough space to store data
-	if neededSpace > int64(float64(di.Free)*0.95) {
+	if neededSpace > int64(float64(di.Free)*diskFillFraction) {
 		return errDiskFull
 	}