diff --git a/src/engine/blkalloc/blk.h b/src/engine/blkalloc/blk.h
index 5429f77bf..a5e71296d 100644
--- a/src/engine/blkalloc/blk.h
+++ b/src/engine/blkalloc/blk.h
@@ -57,7 +57,11 @@ struct BlkId {
     static constexpr uint64_t s_chunk_num_mask{(static_cast< uint64_t >(1) << CHUNK_NUM_BITS) - 1};
 
 public:
-    [[nodiscard]] static constexpr blk_count_t max_blks_in_op() { return (1 << NBLKS_BITS); }
+    [[nodiscard]] static constexpr blk_count_t max_blks_in_op() {
+        static_assert(NBLKS_BITS <= std::numeric_limits< blk_count_t >::digits,
+                      "NBLKS_BITS is too large and may cause overflow in blk_count_t");
+        return (1 << NBLKS_BITS);
+    }
     [[nodiscard]] static constexpr uint64_t max_id_int() {
         return (1ull << (BLK_NUM_BITS + NBLKS_BITS + CHUNK_NUM_BITS)) - 1;
     }
diff --git a/src/engine/blkstore/blkstore.hpp b/src/engine/blkstore/blkstore.hpp
index 9c534b137..db6141ea3 100644
--- a/src/engine/blkstore/blkstore.hpp
+++ b/src/engine/blkstore/blkstore.hpp
@@ -325,11 +325,14 @@ class BlkStore {
     BlkAllocStatus alloc_contiguous_blk(const uint32_t size, blk_alloc_hints& hints, BlkId* const out_blkid) {
         // Allocate a block from the device manager
         assert(size % m_pagesz == 0);
-        const uint32_t nblks{static_cast< uint32_t >(size / m_pagesz)};
+        static uint32_t max_suppoted_size = m_pagesz * std::numeric_limits< blk_count_t >::max();
+        HS_REL_ASSERT_LE(size, max_suppoted_size, "size {} more than max size limit of {}", size, max_suppoted_size);
+
+        const blk_count_t nblks{static_cast< blk_count_t >(size / m_pagesz)};
         hints.is_contiguous = true;
         HS_DBG_ASSERT_LE(nblks, BlkId::max_blks_in_op(), "nblks {} more than max blks {}", nblks,
                          BlkId::max_blks_in_op());
-        return (m_vdev.alloc_contiguous_blk(static_cast< blk_count_t >(nblks), hints, out_blkid));
+        return (m_vdev.alloc_contiguous_blk(nblks, hints, out_blkid));
     }
 
     /* Allocate a new block of the size based on the hints provided */
@@ -341,8 +344,6 @@ class BlkStore {
         // pages * 4096 bytes/page).
         uint32_t nblks{static_cast< uint32_t >(size / m_pagesz)};
         if (nblks <= BlkId::max_blks_in_op()) {
-            auto max_val = std::numeric_limits< blk_count_t >::max();
-            HS_DBG_ASSERT_LE(nblks, max_val, "max_blks_in_op must be less than {}", max_val);
             return (m_vdev.alloc_blk(static_cast< blk_count_t >(nblks), hints, out_blkid));
         } else {
             while (nblks != 0) {
diff --git a/src/homeblks/volume/tests/vol_gtest.cpp b/src/homeblks/volume/tests/vol_gtest.cpp
index 517e3e7f1..d8aa4ef17 100644
--- a/src/homeblks/volume/tests/vol_gtest.cpp
+++ b/src/homeblks/volume/tests/vol_gtest.cpp
@@ -2607,7 +2607,7 @@ SISL_OPTION_GROUP(
     (oob_unmap_enable, "", "oob_unmap_enable", "out-of-band unmap enable 0 or 1",
      ::cxxopts::value< uint32_t >()->default_value("0"), "flag"),
     (max_disk_capacity, "", "max_disk_capacity", "max disk capacity",
-     ::cxxopts::value< uint64_t >()->default_value("10"), "GB"),
+     ::cxxopts::value< uint64_t >()->default_value("20"), "GB"),
     (max_volume, "", "max_volume", "max volume", ::cxxopts::value< uint64_t >()->default_value("50"), "number"),
     (max_num_writes, "", "max_num_writes", "max num of writes", ::cxxopts::value< uint64_t >()->default_value("100000"),
      "number"),
diff --git a/src/homeblks/volume/tool/hs_svc_tool.cpp b/src/homeblks/volume/tool/hs_svc_tool.cpp
index 531d622ca..82a3b0aa6 100644
--- a/src/homeblks/volume/tool/hs_svc_tool.cpp
+++ b/src/homeblks/volume/tool/hs_svc_tool.cpp
@@ -117,7 +117,7 @@ SISL_OPTION_GROUP(hs_svc_tool,
                   (device_list, "", "device_list", "List of device paths",
                    ::cxxopts::value< std::vector< std::string > >(), "path [...]"),
                   (dev_size_gb, "", "dev_size_gb", "size of each device in GB",
-                   ::cxxopts::value< uint64_t >()->default_value("5"), "number"),
+                   ::cxxopts::value< uint64_t >()->default_value("10"), "number"),
                   (zero_boot_sb, "", "zero_boot_sb", "mark homestore init state",
                    ::cxxopts::value< bool >()->default_value("false"), "true or false"),
                   (spdk, "", "spdk", "spdk", ::cxxopts::value< bool >()->default_value("false"), "true or false"));