diff --git a/doc/admin-guide/files/volume.config.en.rst b/doc/admin-guide/files/volume.config.en.rst
index ebae6d4e12a..a05a4b63ef4 100644
--- a/doc/admin-guide/files/volume.config.en.rst
+++ b/doc/admin-guide/files/volume.config.en.rst
@@ -52,6 +52,34 @@ do not allocate all the disk space in the cache, then the extra disk
 space is not used. You can use the extra space later to create new
 volumes without deleting and clearing the existing volumes.
 
+
+Exclusive spans and volume sizes
+================================
+
+In the following sample configuration 2 spans `/dev/disk1` and `/dev/disk2` are defined
+in :file:`storage.config`, where span `/dev/disk2` is assigned to `volume 3` exclusively
+(`volume 3` is forced to an "exclusive" span `/dev/disk2`).
+In :file:`volume.config` there are 3 volumes defined, where `volume 1` and `volume 2`
+occupy span `/dev/disk1` taking each 50% of its space and `volume 3` takes 100% of span
+`/dev/disk2` exclusively.
+
+storage.config::
+
+      /dev/disk1
+      /dev/disk2 volume=3 # <- exclusinve span
+
+volume.config::
+
+      volume=1 scheme=http size=50%
+      volume=2 scheme=http size=50%
+      volume=3 scheme=http size=512 # <- volume forced to a specific exclusive span
+
+It is important to note that when percentages are used to specify volume sizes
+and "exclusive" spans are assigned (forced) to a particular volume (in this case `volume 3`),
+the "exclusive" spans (in this case `/dev/disk2`) are excluded from the total cache
+space when the "non-forced" volumes sizes are calculated (in this case `volume 1` and `volume 2`).
+
+
 Examples
 ========
 
diff --git a/iocore/cache/Cache.cc b/iocore/cache/Cache.cc
index 5ef523e11f9..d1f2a3eb7ae 100644
--- a/iocore/cache/Cache.cc
+++ b/iocore/cache/Cache.cc
@@ -2654,6 +2654,8 @@ cplist_init()
   }
 }
 
+static int fillExclusiveDisks(CacheVol *cp);
+
 void
 cplist_update()
 {
@@ -2709,6 +2711,37 @@ cplist_update()
       cp = cp->link.next;
     }
   }
+
+  // Look for (exclusive) spans forced to a specific volume but not yet referenced by any volumes in cp_list,
+  // if found then create a new volume. This also makes sure new exclusive disk volumes are created first
+  // before any other new volumes to assure proper span free space calculation and proper volume block distribution.
+  for (config_vol = config_volumes.cp_queue.head; config_vol; config_vol = config_vol->link.next) {
+    if (nullptr == config_vol->cachep) {
+      // Find out if this is a forced volume assigned exclusively to a span which was cleared (hence not referenced in cp_list).
+      // Note: non-exclusive cleared spans are not handled here, only the "exclusive"
+      for (int d_no = 0; d_no < gndisks; d_no++) {
+        if (gdisks[d_no]->forced_volume_num == config_vol->number) {
+          CacheVol *new_cp = new CacheVol();
+          if (nullptr != new_cp) {
+            new_cp->disk_vols = (DiskVol **)ats_malloc(gndisks * sizeof(DiskVol *));
+            if (nullptr != new_cp->disk_vols) {
+              memset(new_cp->disk_vols, 0, gndisks * sizeof(DiskVol *));
+              new_cp->vol_number = config_vol->number;
+              new_cp->scheme     = config_vol->scheme;
+              config_vol->cachep = new_cp;
+              fillExclusiveDisks(config_vol->cachep);
+              cp_list.enqueue(new_cp);
+            } else {
+              delete new_cp;
+            }
+          }
+        }
+      }
+    } else {
+      // Fill if this is exclusive disk.
+      fillExclusiveDisks(config_vol->cachep);
+    }
+  }
 }
 
 static int
@@ -2722,20 +2755,31 @@ fillExclusiveDisks(CacheVol *cp)
     if (gdisks[i]->forced_volume_num != volume_number) {
       continue;
     }
-    /* The user had created several volumes before - clear the disk
-       and create one volume for http */
+
+    /* OK, this should be an "exclusive" disk (span). */
+    diskCount++;
+
+    /* There should be a single "forced" volume and no other volumes should exist on this "exclusive" disk (span) */
+    bool found_nonforced_volumes = false;
     for (int j = 0; j < (int)gdisks[i]->header->num_volumes; j++) {
       if (volume_number != gdisks[i]->disk_vols[j]->vol_number) {
-        Note("Clearing Disk: %s", gdisks[i]->path);
-        gdisks[i]->delete_all_volumes();
+        found_nonforced_volumes = true;
         break;
       }
     }
-    diskCount++;
 
+    if (found_nonforced_volumes) {
+      /* The user had created several volumes before - clear the disk and create one volume for http */
+      Note("Clearing Disk: %s", gdisks[i]->path);
+      gdisks[i]->delete_all_volumes();
+    } else if (1 == gdisks[i]->header->num_volumes) {
+      /* "Forced" volumes take the whole disk (span) hence nothing more to do for this span. */
+      continue;
+    }
+
+    /* Now, volumes have been either deleted or did not existing to begin with so we need to create them. */
     int64_t size_diff = gdisks[i]->num_usable_blocks;
     DiskVolBlock *dpb;
-
     do {
       dpb = gdisks[i]->create_volume(volume_number, size_diff, cp->scheme);
       if (dpb) {
@@ -2751,6 +2795,8 @@ fillExclusiveDisks(CacheVol *cp)
       }
     } while ((size_diff > 0));
   }
+
+  /* Report back the number of disks (spans) that were assigned to volume specified by volume_number. */
   return diskCount;
 }
 
@@ -2815,7 +2861,11 @@ cplist_reconfigure()
     /* sum up the total space available on all the disks.
        round down the space to 128 megabytes */
     for (int i = 0; i < gndisks; i++) {
-      tot_space_in_blks += (gdisks[i]->num_usable_blocks / blocks_per_vol) * blocks_per_vol;
+      // Exclude exclusive disks (with forced volumes) from the following total space calculation,
+      // in such a way forced volumes will not impact volume percentage calculations.
+      if (-1 == gdisks[i]->forced_volume_num) {
+        tot_space_in_blks += (gdisks[i]->num_usable_blocks / blocks_per_vol) * blocks_per_vol;
+      }
     }
 
     double percent_remaining = 100.00;
@@ -2843,16 +2893,8 @@ cplist_reconfigure()
       Debug("cache_hosting", "Volume: %d Size: %" PRId64, config_vol->number, (int64_t)config_vol->size);
     }
     cplist_update();
-    /* go through volume config and grow and create volumes */
-
-    for (config_vol = config_volumes.cp_queue.head; config_vol; config_vol = config_vol->link.next) {
-      // if volume is given exclusive disks, fill here and continue
-      if (!config_vol->cachep) {
-        continue;
-      }
-      fillExclusiveDisks(config_vol->cachep);
-    }
 
+    /* go through volume config and grow and create volumes */
     for (config_vol = config_volumes.cp_queue.head; config_vol; config_vol = config_vol->link.next) {
       size = config_vol->size;
       if (size < 128) {