diff --git a/block-cache/block_cache.h b/block-cache/block_cache.h
index 4bc6667..5de2c44 100644
--- a/block-cache/block_cache.h
+++ b/block-cache/block_cache.h
@@ -26,12 +26,14 @@ namespace bcache {
 		virtual ~validator() {}
 
 		virtual void check(void const *data, block_address location) const = 0;
+		virtual bool check_raw(void const *data) const = 0;
 		virtual void prepare(void *data, block_address location) const = 0;
 	};
 
 	class noop_validator : public validator {
 	public:
 		void check(void const *data, block_address location) const {}
+		bool check_raw(void const *data) const {return true;}
 		void prepare(void *data, block_address location) const {}
 	};
 
diff --git a/caching/superblock.cc b/caching/superblock.cc
index 2edd6c1..3270b3f 100644
--- a/caching/superblock.cc
+++ b/caching/superblock.cc
@@ -292,6 +292,15 @@ namespace validator {
 				throw checksum_error("bad checksum in superblock");
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(raw);
+			crc32c sum(SUPERBLOCK_CSUM_SEED);
+			sum.append(&sbd->flags, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(sbd->csum))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			superblock_disk *sbd = reinterpret_cast<superblock_disk *>(raw);
 			crc32c sum(SUPERBLOCK_CSUM_SEED);
diff --git a/era/superblock.cc b/era/superblock.cc
index e013064..f61a542 100644
--- a/era/superblock.cc
+++ b/era/superblock.cc
@@ -219,6 +219,15 @@ namespace era_validator {
 				throw checksum_error("bad checksum in superblock");
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(raw);
+			crc32c sum(SUPERBLOCK_CSUM_SEED);
+			sum.append(&sbd->flags, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(sbd->csum))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			superblock_disk *sbd = reinterpret_cast<superblock_disk *>(raw);
 			crc32c sum(SUPERBLOCK_CSUM_SEED);
diff --git a/persistent-data/data-structures/array.h b/persistent-data/data-structures/array.h
index 1b87160..d7b1f70 100644
--- a/persistent-data/data-structures/array.h
+++ b/persistent-data/data-structures/array.h
@@ -43,6 +43,15 @@ namespace persistent_data {
 					throw checksum_error("bad block nr in array block");
 			}
 
+			virtual bool check_raw(void const *raw) const {
+				array_block_disk const *data = reinterpret_cast<array_block_disk const *>(raw);
+				crc32c sum(ARRAY_CSUM_XOR);
+				sum.append(&data->max_entries, MD_BLOCK_SIZE - sizeof(uint32_t));
+				if (sum.get_sum() != to_cpu<uint32_t>(data->csum))
+					return false;
+				return true;
+			}
+
 			virtual void prepare(void *raw, block_address location) const {
 				array_block_disk *data = reinterpret_cast<array_block_disk *>(raw);
 				data->blocknr = to_disk<base::le64, uint64_t>(location);
diff --git a/persistent-data/data-structures/btree.tcc b/persistent-data/data-structures/btree.tcc
index 06d0deb..3fc96e4 100644
--- a/persistent-data/data-structures/btree.tcc
+++ b/persistent-data/data-structures/btree.tcc
@@ -32,7 +32,6 @@ namespace {
 	using namespace persistent_data;
 	using namespace btree_detail;
 	using namespace std;
-
 }
 
 //----------------------------------------------------------------
diff --git a/persistent-data/space-maps/disk.cc b/persistent-data/space-maps/disk.cc
index cab9583..ed7bae8 100644
--- a/persistent-data/space-maps/disk.cc
+++ b/persistent-data/space-maps/disk.cc
@@ -50,6 +50,15 @@ namespace {
 				throw checksum_error("bad block nr in space map bitmap");
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			bitmap_header const *data = reinterpret_cast<bitmap_header const *>(raw);
+			crc32c sum(BITMAP_CSUM_XOR);
+			sum.append(&data->not_used, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(data->csum))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			bitmap_header *data = reinterpret_cast<bitmap_header *>(raw);
 			data->blocknr = to_disk<base::le64, uint64_t>(location);
@@ -77,6 +86,15 @@ namespace {
 				throw checksum_error("bad block nr in metadata index block");
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			metadata_index const *mi = reinterpret_cast<metadata_index const *>(raw);
+			crc32c sum(INDEX_CSUM_XOR);
+			sum.append(&mi->padding_, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(mi->csum_))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			metadata_index *mi = reinterpret_cast<metadata_index *>(raw);
 			mi->blocknr_ = to_disk<base::le64, uint64_t>(location);
diff --git a/persistent-data/validators.cc b/persistent-data/validators.cc
index b9c163c..a50947d 100644
--- a/persistent-data/validators.cc
+++ b/persistent-data/validators.cc
@@ -31,6 +31,16 @@ namespace {
 			}
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			disk_node const *data = reinterpret_cast<disk_node const *>(raw);
+			node_header const *n = &data->header;
+			crc32c sum(BTREE_CSUM_XOR);
+			sum.append(&n->flags, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(n->csum))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			disk_node *data = reinterpret_cast<disk_node *>(raw);
 			node_header *n = &data->header;
diff --git a/thin-provisioning/superblock.cc b/thin-provisioning/superblock.cc
index fb0d17e..f63ed52 100644
--- a/thin-provisioning/superblock.cc
+++ b/thin-provisioning/superblock.cc
@@ -98,6 +98,15 @@ namespace {
 			}
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			superblock_disk const *sbd = reinterpret_cast<superblock_disk const *>(raw);
+			crc32c sum(SUPERBLOCK_CSUM_SEED);
+			sum.append(&sbd->flags_, MD_BLOCK_SIZE - sizeof(uint32_t));
+			if (sum.get_sum() != to_cpu<uint32_t>(sbd->csum_))
+				return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			superblock_disk *sbd = reinterpret_cast<superblock_disk *>(raw);
 			crc32c sum(SUPERBLOCK_CSUM_SEED);
diff --git a/unit-tests/block_t.cc b/unit-tests/block_t.cc
index c2a6d58..1a61d2b 100644
--- a/unit-tests/block_t.cc
+++ b/unit-tests/block_t.cc
@@ -44,6 +44,14 @@ namespace {
  					throw runtime_error("validator check zero");
 		}
 
+		virtual bool check_raw(void const *raw) const {
+			unsigned char const *data = reinterpret_cast<unsigned char const *>(raw);
+			for (unsigned b = 0; b < BlockSize; b++)
+				if (data[b] != 0)
+					return false;
+			return true;
+		}
+
 		virtual void prepare(void *raw, block_address location) const {
 			unsigned char *data = reinterpret_cast<unsigned char *>(raw);
 			for (unsigned b = 0; b < BlockSize; b++)