diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index 9e6cfea..5e5546d 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -107,9 +107,9 @@
 struct CowHeaderV3 : public CowHeader {
     // Number of sequence data stored (each of which is a 32 byte integer)
     uint64_t sequence_data_count;
-    // number of currently written resume points
+    // Number of currently written resume points &&
     uint32_t resume_point_count;
-    // Size, in bytes, of the CowResumePoint buffer.
+    // Number of max resume points that can be written
     uint32_t resume_point_max;
     // Number of CowOperationV3 structs in the operation buffer, currently and total
     // region size.
@@ -232,19 +232,23 @@
     return op.source_info & kCowOpSourceInfoDataMask;
 }
 
-static constexpr off_t GetOpOffset(uint32_t op_index, const CowHeaderV3 header) {
-    return header.prefix.header_size + header.buffer_size +
-           (header.resume_point_max * sizeof(ResumePoint)) + (op_index * sizeof(CowOperationV3));
-}
-static constexpr off_t GetDataOffset(const CowHeaderV3 header) {
-    return header.prefix.header_size + header.buffer_size +
-           (header.resume_point_max * sizeof(ResumePoint)) +
-           header.op_count_max * sizeof(CowOperation);
-}
-static constexpr off_t GetResumeOffset(const CowHeaderV3 header) {
+static constexpr off_t GetSequenceOffset(const CowHeaderV3& header) {
     return header.prefix.header_size + header.buffer_size;
 }
 
+static constexpr off_t GetResumeOffset(const CowHeaderV3& header) {
+    return GetSequenceOffset(header) + (header.sequence_data_count * sizeof(uint32_t));
+}
+
+static constexpr off_t GetOpOffset(uint32_t op_index, const CowHeaderV3& header) {
+    return GetResumeOffset(header) + (header.resume_point_max * sizeof(ResumePoint)) +
+           (op_index * sizeof(CowOperationV3));
+}
+
+static constexpr off_t GetDataOffset(const CowHeaderV3& header) {
+    return GetOpOffset(header.op_count_max, header);
+}
+
 struct CowFooter {
     CowFooterOperation op;
     uint8_t unused[64];
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
index c87b32d..bf4c79f 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_reader.h
@@ -16,8 +16,6 @@
 
 #include <stdint.h>
 
-#include <deque>
-#include <functional>
 #include <memory>
 #include <optional>
 #include <unordered_map>
@@ -169,6 +167,12 @@
   private:
     bool ParseV2(android::base::borrowed_fd fd, std::optional<uint64_t> label);
     bool PrepMergeOps();
+    // sequence data is stored as an operation with actual data residing in the data offset.
+    bool GetSequenceDataV2(std::vector<uint32_t>* merge_op_blocks, std::vector<int>* other_ops,
+                           std::unordered_map<uint32_t, int>* block_map);
+    // v3 of the cow writes sequence data within its own separate sequence buffer.
+    bool GetSequenceData(std::vector<uint32_t>* merge_op_blocks, std::vector<int>* other_ops,
+                         std::unordered_map<uint32_t, int>* block_map);
     uint64_t FindNumCopyops();
     uint8_t GetCompressionType();
 
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 8412879..7b5370c 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -24,6 +24,7 @@
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
+#include <libsnapshot/cow_format.h>
 #include <libsnapshot/cow_reader.h>
 #include <zlib.h>
 
@@ -265,52 +266,31 @@
 //                        Replace-op-4, Zero-op-9, Replace-op-5 }
 //==============================================================
 bool CowReader::PrepMergeOps() {
-    auto merge_op_blocks = std::make_unique<std::vector<uint32_t>>();
     std::vector<int> other_ops;
-    auto seq_ops_set = std::unordered_set<uint32_t>();
-    auto block_map = std::make_unique<std::unordered_map<uint32_t, int>>();
-    size_t num_seqs = 0;
-    size_t read;
+    std::vector<uint32_t> merge_op_blocks;
+    std::unordered_map<uint32_t, int> block_map;
 
-    for (size_t i = 0; i < ops_->size(); i++) {
-        auto& current_op = ops_->data()[i];
-
-        if (current_op.type == kCowSequenceOp) {
-            size_t seq_len = current_op.data_length / sizeof(uint32_t);
-
-            merge_op_blocks->resize(merge_op_blocks->size() + seq_len);
-            if (!GetRawBytes(&current_op, &merge_op_blocks->data()[num_seqs],
-                             current_op.data_length, &read)) {
-                PLOG(ERROR) << "Failed to read sequence op!";
-                return false;
-            }
-            for (size_t j = num_seqs; j < num_seqs + seq_len; j++) {
-                seq_ops_set.insert(merge_op_blocks->data()[j]);
-            }
-            num_seqs += seq_len;
-        }
-
-        if (IsMetadataOp(current_op)) {
-            continue;
-        }
-
-        // Sequence ops must be the first ops in the stream.
-        if (seq_ops_set.empty() && IsOrderedOp(current_op)) {
-            merge_op_blocks->emplace_back(current_op.new_block);
-        } else if (seq_ops_set.count(current_op.new_block) == 0) {
-            other_ops.push_back(current_op.new_block);
-        }
-        block_map->insert({current_op.new_block, i});
+    switch (header_.prefix.major_version) {
+        case 1:
+        case 2:
+            GetSequenceDataV2(&merge_op_blocks, &other_ops, &block_map);
+            break;
+        case 3:
+            GetSequenceData(&merge_op_blocks, &other_ops, &block_map);
+            break;
+        default:
+            break;
     }
-    for (auto block : *merge_op_blocks) {
-        if (block_map->count(block) == 0) {
+
+    for (auto block : merge_op_blocks) {
+        if (block_map.count(block) == 0) {
             LOG(ERROR) << "Invalid Sequence Ops. Could not find Cow Op for new block " << block;
             return false;
         }
     }
 
-    if (merge_op_blocks->size() > header_.num_merge_ops) {
-        num_ordered_ops_to_merge_ = merge_op_blocks->size() - header_.num_merge_ops;
+    if (merge_op_blocks.size() > header_.num_merge_ops) {
+        num_ordered_ops_to_merge_ = merge_op_blocks.size() - header_.num_merge_ops;
     } else {
         num_ordered_ops_to_merge_ = 0;
     }
@@ -326,9 +306,9 @@
         std::sort(other_ops.begin(), other_ops.end(), std::greater<int>());
     }
 
-    merge_op_blocks->insert(merge_op_blocks->end(), other_ops.begin(), other_ops.end());
+    merge_op_blocks.insert(merge_op_blocks.end(), other_ops.begin(), other_ops.end());
 
-    num_total_data_ops_ = merge_op_blocks->size();
+    num_total_data_ops_ = merge_op_blocks.size();
     if (header_.num_merge_ops > 0) {
         merge_op_start_ = header_.num_merge_ops;
     }
@@ -338,24 +318,94 @@
         // the ops vector as required for merge operations.
         auto merge_ops_buffer = std::make_shared<std::vector<CowOperation>>();
         merge_ops_buffer->reserve(num_total_data_ops_);
-        for (auto block : *merge_op_blocks) {
-            merge_ops_buffer->emplace_back(ops_->data()[block_map->at(block)]);
+        for (auto block : merge_op_blocks) {
+            merge_ops_buffer->emplace_back(ops_->data()[block_map.at(block)]);
         }
         ops_->clear();
         ops_ = merge_ops_buffer;
         ops_->shrink_to_fit();
     } else {
-        for (auto block : *merge_op_blocks) {
-            block_pos_index_->push_back(block_map->at(block));
+        for (auto block : merge_op_blocks) {
+            block_pos_index_->push_back(block_map.at(block));
         }
     }
 
-    block_map->clear();
-    merge_op_blocks->clear();
+    block_map.clear();
+    merge_op_blocks.clear();
 
     return true;
 }
 
+bool CowReader::GetSequenceDataV2(std::vector<uint32_t>* merge_op_blocks,
+                                  std::vector<int>* other_ops,
+                                  std::unordered_map<uint32_t, int>* block_map) {
+    auto seq_ops_set = std::unordered_set<uint32_t>();
+    size_t num_seqs = 0;
+    size_t read;
+    for (size_t i = 0; i < ops_->size(); i++) {
+        auto& current_op = ops_->data()[i];
+
+        if (current_op.type == kCowSequenceOp) {
+            size_t seq_len = current_op.data_length / sizeof(uint32_t);
+
+            merge_op_blocks->resize(merge_op_blocks->size() + seq_len);
+            if (!GetRawBytes(&current_op, &merge_op_blocks->data()[num_seqs],
+                             current_op.data_length, &read)) {
+                PLOG(ERROR) << "Failed to read sequence op!";
+                return false;
+            }
+            for (size_t j = num_seqs; j < num_seqs + seq_len; j++) {
+                seq_ops_set.insert(merge_op_blocks->at(j));
+            }
+            num_seqs += seq_len;
+        }
+
+        if (IsMetadataOp(current_op)) {
+            continue;
+        }
+
+        // Sequence ops must be the first ops in the stream.
+        if (seq_ops_set.empty() && IsOrderedOp(current_op)) {
+            merge_op_blocks->emplace_back(current_op.new_block);
+        } else if (seq_ops_set.count(current_op.new_block) == 0) {
+            other_ops->push_back(current_op.new_block);
+        }
+        block_map->insert({current_op.new_block, i});
+    }
+    return false;
+}
+
+bool CowReader::GetSequenceData(std::vector<uint32_t>* merge_op_blocks, std::vector<int>* other_ops,
+                                std::unordered_map<uint32_t, int>* block_map) {
+    std::unordered_set<uint32_t> seq_ops_set;
+    // read sequence ops data
+    merge_op_blocks->resize(header_.sequence_data_count);
+    if (!android::base::ReadFullyAtOffset(
+                fd_, merge_op_blocks->data(),
+                header_.sequence_data_count * sizeof(merge_op_blocks->at(0)),
+                GetSequenceOffset(header_))) {
+        PLOG(ERROR) << "failed to read sequence buffer. seq_data_count: "
+                    << header_.sequence_data_count << " at offset: " << GetSequenceOffset(header_);
+        return false;
+    }
+    seq_ops_set.reserve(merge_op_blocks->size());
+    for (auto& i : *merge_op_blocks) {
+        seq_ops_set.insert(i);
+    }
+    // read ordered op data
+    for (size_t i = 0; i < ops_->size(); i++) {
+        auto& current_op = ops_->data()[i];
+        // Sequence ops must be the first ops in the stream.
+        if (seq_ops_set.empty()) {
+            merge_op_blocks->emplace_back(current_op.new_block);
+        } else if (seq_ops_set.count(current_op.new_block) == 0) {
+            other_ops->push_back(current_op.new_block);
+        }
+        block_map->insert({current_op.new_block, i});
+    }
+    return true;
+}
+
 bool CowReader::VerifyMergeOps() {
     auto itr = GetMergeOpIter(true);
     std::unordered_map<uint64_t, const CowOperation*> overwritten_blocks;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
index 9f857ee..9ac1448 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/test_v3.cpp
@@ -520,5 +520,106 @@
     resume_point_max = 4;
     */
 }
+
+TEST_F(CowTestV3, SequenceTest) {
+    CowOptions options;
+    options.op_count_max = std::numeric_limits<uint32_t>::max();
+    auto writer = CreateCowWriter(3, options, GetCowFd());
+    // sequence data. This just an arbitrary set of integers that specify the merge order. The
+    // actual calculation is done by update_engine and passed to writer. All we care about here is
+    // writing that data correctly
+    const int seq_len = std::numeric_limits<uint16_t>::max() / sizeof(uint32_t) + 1;
+    uint32_t sequence[seq_len];
+    for (int i = 0; i < seq_len; i++) {
+        sequence[i] = i + 1;
+    }
+
+    ASSERT_TRUE(writer->AddSequenceData(seq_len, sequence));
+    ASSERT_TRUE(writer->AddZeroBlocks(1, seq_len));
+    ASSERT_TRUE(writer->Finalize());
+
+    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
+
+    CowReader reader;
+    ASSERT_TRUE(reader.Parse(cow_->fd));
+    auto iter = reader.GetRevMergeOpIter();
+
+    for (int i = 0; i < seq_len; i++) {
+        ASSERT_TRUE(!iter->AtEnd());
+        const auto& op = iter->Get();
+
+        ASSERT_EQ(op->new_block, seq_len - i);
+
+        iter->Next();
+    }
+    ASSERT_TRUE(iter->AtEnd());
+}
+
+TEST_F(CowTestV3, MissingSeqOp) {
+    CowOptions options;
+    options.op_count_max = std::numeric_limits<uint32_t>::max();
+    auto writer = CreateCowWriter(3, options, GetCowFd());
+    const int seq_len = 10;
+    uint32_t sequence[seq_len];
+    for (int i = 0; i < seq_len; i++) {
+        sequence[i] = i + 1;
+    }
+    ASSERT_TRUE(writer->AddSequenceData(seq_len, sequence));
+    ASSERT_TRUE(writer->AddZeroBlocks(1, seq_len - 1));
+    ASSERT_TRUE(writer->Finalize());
+
+    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
+
+    CowReader reader;
+    ASSERT_FALSE(reader.Parse(cow_->fd));
+}
+
+TEST_F(CowTestV3, ResumeSeqOp) {
+    CowOptions options;
+    options.op_count_max = std::numeric_limits<uint32_t>::max();
+    auto writer = std::make_unique<CowWriterV3>(options, GetCowFd());
+    const int seq_len = 10;
+    uint32_t sequence[seq_len];
+    for (int i = 0; i < seq_len; i++) {
+        sequence[i] = i + 1;
+    }
+    ASSERT_TRUE(writer->Initialize());
+
+    ASSERT_TRUE(writer->AddSequenceData(seq_len, sequence));
+    ASSERT_TRUE(writer->AddZeroBlocks(1, seq_len / 2));
+    ASSERT_TRUE(writer->AddLabel(1));
+    ASSERT_TRUE(writer->AddZeroBlocks(1 + seq_len / 2, 1));
+
+    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
+    auto reader = std::make_unique<CowReader>();
+    ASSERT_TRUE(reader->Parse(cow_->fd, 1));
+    auto itr = reader->GetRevMergeOpIter();
+    ASSERT_TRUE(itr->AtEnd());
+
+    writer = std::make_unique<CowWriterV3>(options, GetCowFd());
+    ASSERT_TRUE(writer->Initialize({1}));
+    ASSERT_TRUE(writer->AddZeroBlocks(1 + seq_len / 2, seq_len / 2));
+    ASSERT_TRUE(writer->Finalize());
+
+    ASSERT_EQ(lseek(cow_->fd, 0, SEEK_SET), 0);
+
+    reader = std::make_unique<CowReader>();
+    ASSERT_TRUE(reader->Parse(cow_->fd));
+
+    auto iter = reader->GetRevMergeOpIter();
+
+    uint64_t expected_block = 10;
+    while (!iter->AtEnd() && expected_block > 0) {
+        ASSERT_FALSE(iter->AtEnd());
+        const auto& op = iter->Get();
+
+        ASSERT_EQ(op->new_block, expected_block);
+
+        iter->Next();
+        expected_block--;
+    }
+    ASSERT_EQ(expected_block, 0);
+    ASSERT_TRUE(iter->AtEnd());
+}
 }  // namespace snapshot
 }  // namespace android
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
index 81ccea9..b36c6f3 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/writer_v3.cpp
@@ -316,9 +316,14 @@
 }
 
 bool CowWriterV3::EmitSequenceData(size_t num_ops, const uint32_t* data) {
-    LOG(ERROR) << __LINE__ << " " << __FILE__ << " <- function here should never be called";
-    if (num_ops && data) return false;
-    return false;
+    // TODO: size sequence buffer based on options
+    header_.sequence_data_count = num_ops;
+    if (!android::base::WriteFullyAtOffset(fd_, data, sizeof(data[0]) * num_ops,
+                                           GetSequenceOffset(header_))) {
+        PLOG(ERROR) << "writing sequence buffer failed";
+        return false;
+    }
+    return true;
 }
 
 bool CowWriterV3::WriteOperation(const CowOperationV3& op, const void* data, size_t size) {