diff --git a/src/include/homestore/vchunk.h b/src/include/homestore/vchunk.h
index f34ed0f4a..a88f17361 100644
--- a/src/include/homestore/vchunk.h
+++ b/src/include/homestore/vchunk.h
@@ -30,6 +30,8 @@ class VChunk {
     void set_user_private(const sisl::blob& data);
     const uint8_t* get_user_private() const;
     blk_num_t available_blks() const;
+    blk_num_t get_freeable_nblks() const;
+    blk_num_t get_defrag_nblks() const;
     uint32_t get_pdev_id() const;
     uint16_t get_chunk_id() const;
     cshared< Chunk > get_internal_chunk() const;
diff --git a/src/lib/blkalloc/blk_allocator.h b/src/lib/blkalloc/blk_allocator.h
index 8f63aa0f8..172124b1b 100644
--- a/src/lib/blkalloc/blk_allocator.h
+++ b/src/lib/blkalloc/blk_allocator.h
@@ -157,6 +157,8 @@ class BlkAllocator {
     virtual void free_on_disk(BlkId const& bid) = 0;
 
     virtual blk_num_t available_blks() const = 0;
+    virtual blk_num_t get_freeable_nblks() const = 0;
+    virtual blk_num_t get_defrag_nblks() const = 0;
     virtual blk_num_t get_used_blks() const = 0;
     virtual bool is_blk_alloced(BlkId const& b, bool use_lock = false) const = 0;
     virtual bool is_blk_alloced_on_disk(BlkId const& b, bool use_lock = false) const = 0;
diff --git a/src/lib/blkalloc/fixed_blk_allocator.cpp b/src/lib/blkalloc/fixed_blk_allocator.cpp
index 3b1776d7c..2e9e5ae03 100644
--- a/src/lib/blkalloc/fixed_blk_allocator.cpp
+++ b/src/lib/blkalloc/fixed_blk_allocator.cpp
@@ -74,6 +74,19 @@ void FixedBlkAllocator::free(BlkId const& b) {
 }
 
 blk_num_t FixedBlkAllocator::available_blks() const { return m_blk_q.sizeGuess(); }
+
+blk_num_t FixedBlkAllocator::get_freeable_nblks() const {
+    // TODO: implement this
+    HS_DBG_ASSERT_EQ(false, true, "FixedBlkAllocator get_freeable_nblks Not implemented");
+    return 0;
+}
+
+blk_num_t FixedBlkAllocator::get_defrag_nblks() const {
+    // TODO: implement this
+    HS_DBG_ASSERT_EQ(false, true, "FixedBlkAllocator get_defrag_nblks Not implemented");
+    return 0;
+}
+
 blk_num_t FixedBlkAllocator::get_used_blks() const { return get_total_blks() - available_blks(); }
 
 std::string FixedBlkAllocator::to_string() const {
diff --git a/src/lib/blkalloc/varsize_blk_allocator.cpp b/src/lib/blkalloc/varsize_blk_allocator.cpp
index ac44ab1bf..edc4dbbb9 100644
--- a/src/lib/blkalloc/varsize_blk_allocator.cpp
+++ b/src/lib/blkalloc/varsize_blk_allocator.cpp
@@ -716,6 +716,19 @@ bool VarsizeBlkAllocator::is_blk_alloced(BlkId const& bid, bool use_lock) const
 }
 
 blk_num_t VarsizeBlkAllocator::available_blks() const { return get_total_blks() - get_used_blks(); }
+
+blk_num_t VarsizeBlkAllocator::get_freeable_nblks() const {
+    // TODO: implement this
+    BLKALLOC_REL_ASSERT(false, "VarsizeBlkAllocator get_freeable_nblks Not implemented")
+    return 0;
+}
+
+blk_num_t VarsizeBlkAllocator::get_defrag_nblks() const {
+    // TODO: implement this
+    BLKALLOC_REL_ASSERT(false, "VarsizeBlkAllocator get_defrag_nblks Not implemented")
+    return 0;
+}
+
 blk_num_t VarsizeBlkAllocator::get_used_blks() const { return get_alloced_blk_count(); }
 
 #ifdef _PRERELEASE
diff --git a/src/lib/blkalloc/varsize_blk_allocator.h b/src/lib/blkalloc/varsize_blk_allocator.h
index 09f13240a..c6c1aa1d1 100644
--- a/src/lib/blkalloc/varsize_blk_allocator.h
+++ b/src/lib/blkalloc/varsize_blk_allocator.h
@@ -217,6 +217,8 @@ class VarsizeBlkAllocator : public BitmapBlkAllocator {
     void free(BlkId const& blk_id) override;
 
     blk_num_t available_blks() const override;
+    blk_num_t get_freeable_nblks() const override;
+    blk_num_t get_defrag_nblks() const override;
     blk_num_t get_used_blks() const override;
     bool is_blk_alloced(BlkId const& in_bid, bool use_lock = false) const override;
     std::string to_string() const override;
diff --git a/src/lib/device/vchunk.cpp b/src/lib/device/vchunk.cpp
index 54dc54604..a154f39a9 100644
--- a/src/lib/device/vchunk.cpp
+++ b/src/lib/device/vchunk.cpp
@@ -25,6 +25,10 @@ const uint8_t* VChunk::get_user_private() const { return m_internal_chunk->user_
 
 blk_num_t VChunk::available_blks() const { return m_internal_chunk->blk_allocator()->available_blks(); }
 
+blk_num_t VChunk::get_freeable_nblks() const { return m_internal_chunk->blk_allocator()->get_freeable_nblks(); }
+
+blk_num_t VChunk::get_defrag_nblks() const { return m_internal_chunk->blk_allocator()->get_defrag_nblks(); }
+
 uint32_t VChunk::get_pdev_id() const { return m_internal_chunk->physical_dev()->pdev_id(); }
 
 uint16_t VChunk::get_chunk_id() const { return m_internal_chunk->chunk_id(); }