diff --git a/src/api-copy.c b/src/api-copy.c
index a87c6ea7..d767839f 100644
--- a/src/api-copy.c
+++ b/src/api-copy.c
@@ -479,7 +479,7 @@ __cold static int copy_with_compacting(MDBX_env *env, MDBX_txn *txn, mdbx_fileha
   if (meta->geometry.now != meta->geometry.first_unallocated) {
     const size_t whole_size = pgno2bytes(env, meta->geometry.now);
     if (!dest_is_pipe)
-      return osal_ftruncate(fd, whole_size);
+      return osal_fallocate(fd, whole_size);
 
     const size_t used_size = pgno2bytes(env, meta->geometry.first_unallocated);
     memset(data_buffer, 0, (size_t)MDBX_ENVCOPY_WRITEBUF);
@@ -648,7 +648,7 @@ retry_snap_meta:
   /* Extend file if required */
   if (likely(rc == MDBX_SUCCESS) && whole_size != used_size) {
     if (!dest_is_pipe)
-      rc = osal_ftruncate(fd, whole_size);
+      rc = osal_fallocate(fd, whole_size);
     else {
       memset(data_buffer, 0, (size_t)MDBX_ENVCOPY_WRITEBUF);
       for (size_t offset = used_size; rc == MDBX_SUCCESS && offset < whole_size;) {
diff --git a/src/dxb.c b/src/dxb.c
index 6f500636..4136a9e4 100644
--- a/src/dxb.c
+++ b/src/dxb.c
@@ -532,7 +532,7 @@ __cold int dxb_setup(MDBX_env *env, const int lck_rc, const mdbx_mode_t mode_bit
     if (unlikely(err != MDBX_SUCCESS))
       return err;
 
-    err = osal_ftruncate(env->lazy_fd, env->dxb_mmap.filesize = env->dxb_mmap.current = env->geo_in_bytes.now);
+    err = osal_fallocate(env->lazy_fd, env->dxb_mmap.filesize = env->dxb_mmap.current = env->geo_in_bytes.now);
     if (unlikely(err != MDBX_SUCCESS))
       return err;
 
@@ -682,7 +682,7 @@ __cold int dxb_setup(MDBX_env *env, const int lck_rc, const mdbx_mode_t mode_bit
       !(env->flags & MDBX_NORDAHEAD) && mdbx_is_readahead_reasonable(used_bytes, 0) == MDBX_RESULT_TRUE;
 
   err = osal_mmap(env->flags, &env->dxb_mmap, env->geo_in_bytes.now, env->geo_in_bytes.upper,
-                  (lck_rc && env->stuck_meta < 0) ? MMAP_OPTION_TRUNCATE : 0, env->pathname.dxb);
+                  (lck_rc && env->stuck_meta < 0) ? MMAP_OPTION_SETLENGTH : 0, env->pathname.dxb);
   if (unlikely(err != MDBX_SUCCESS))
     return err;
 
diff --git a/src/lck.c b/src/lck.c
index 73ce13e0..b71a7588 100644
--- a/src/lck.c
+++ b/src/lck.c
@@ -62,9 +62,9 @@ __cold static int lck_setup_locked(MDBX_env *env) {
   }
   env->max_readers = (maxreaders <= MDBX_READERS_LIMIT) ? (unsigned)maxreaders : (unsigned)MDBX_READERS_LIMIT;
 
-  err =
-      osal_mmap((env->flags & MDBX_EXCLUSIVE) | MDBX_WRITEMAP, &env->lck_mmap, (size_t)size, (size_t)size,
-                lck_seize_rc ? MMAP_OPTION_TRUNCATE | MMAP_OPTION_SEMAPHORE : MMAP_OPTION_SEMAPHORE, env->pathname.lck);
+  err = osal_mmap((env->flags & MDBX_EXCLUSIVE) | MDBX_WRITEMAP, &env->lck_mmap, (size_t)size, (size_t)size,
+                  lck_seize_rc ? MMAP_OPTION_SETLENGTH | MMAP_OPTION_SEMAPHORE : MMAP_OPTION_SEMAPHORE,
+                  env->pathname.lck);
   if (unlikely(err != MDBX_SUCCESS))
     return err;
 
diff --git a/src/osal.c b/src/osal.c
index b83e2776..b32b74c3 100644
--- a/src/osal.c
+++ b/src/osal.c
@@ -1594,6 +1594,7 @@ MDBX_INTERNAL int osal_is_pipe(mdbx_filehandle_t fd) {
 #endif
 }
 
+/* truncate file: just set the length of a file */
 MDBX_INTERNAL int osal_ftruncate(mdbx_filehandle_t fd, uint64_t length) {
 #if defined(_WIN32) || defined(_WIN64)
   if (imports.SetFileInformationByHandle) {
@@ -1613,6 +1614,23 @@ MDBX_INTERNAL int osal_ftruncate(mdbx_filehandle_t fd, uint64_t length) {
 #endif
 }
 
+/* extend file: set the length of a file AND ensure the space has been allocated */
+MDBX_INTERNAL int osal_fallocate(mdbx_filehandle_t fd, uint64_t length) {
+  assert(length > 0);
+  int err = MDBX_RESULT_TRUE;
+#if (defined(__linux__) || defined(__gnu_linux__)) &&                                                                  \
+    ((defined(_GNU_SOURCE) && __GLIBC_PREREQ(2, 10)) || (defined(__ANDROID_API__) && __ANDROID_API__ >= 21))
+  err = fallocate(fd, 0, 0, length) ? ignore_enosys_and_eremote(errno) : MDBX_SUCCESS;
+#elif defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L && !defined(__APPLE__)
+  err = posix_fallocate(fd, 0, length) ? ignore_enosys_and_eremote(errno) : MDBX_SUCCESS;
+#elif defined(__APPLE__)
+  fstore_t store = {F_ALLOCATEALL, F_PEOFPOSMODE, 0, length, 0};
+  if (fcntl(fd, F_PREALLOCATE, &store))
+    err = ignore_enosys_and_eremote(errno);
+#endif /* Apple */
+  return (err == MDBX_RESULT_TRUE) ? osal_ftruncate(fd, length) : err;
+}
+
 MDBX_INTERNAL int osal_fseek(mdbx_filehandle_t fd, uint64_t pos) {
 #if defined(_WIN32) || defined(_WIN64)
   LARGE_INTEGER li;
@@ -2063,8 +2081,8 @@ MDBX_INTERNAL int osal_mmap(const int flags, osal_mmap_t *map, size_t size, cons
   if (unlikely(err != MDBX_SUCCESS))
     return err;
 
-  if ((flags & MDBX_RDONLY) == 0 && (options & MMAP_OPTION_TRUNCATE) != 0) {
-    err = osal_ftruncate(map->fd, size);
+  if ((flags & MDBX_RDONLY) == 0 && (options & MMAP_OPTION_SETLENGTH) != 0) {
+    err = osal_fallocate(map->fd, size);
     VERBOSE("ftruncate %zu, err %d", size, err);
     if (err != MDBX_SUCCESS)
       return err;
@@ -2310,7 +2328,7 @@ retry_file_and_section:
   }
 
   if ((flags & MDBX_RDONLY) == 0 && map->filesize != size) {
-    err = osal_ftruncate(map->fd, size);
+    err = osal_fallocate(map->fd, size);
     if (err == MDBX_SUCCESS)
       map->filesize = size;
     /* ignore error, because Windows unable shrink file
@@ -2388,10 +2406,15 @@ retry_mapview:;
       rc = MDBX_EPERM;
     map->current = (map->filesize > limit) ? limit : (size_t)map->filesize;
   } else {
-    if (size > map->filesize || (size < map->filesize && (flags & txn_shrink_allowed))) {
-      rc = osal_ftruncate(map->fd, size);
-      VERBOSE("ftruncate %zu, err %d", size, rc);
-      if (rc != MDBX_SUCCESS)
+    if (map->filesize != size) {
+      if (size > map->filesize) {
+        rc = osal_fallocate(map->fd, size);
+        VERBOSE("f%s-%s %zu, err %d", "allocate", "extend", size, rc);
+      } else if (flags & txn_shrink_allowed) {
+        rc = osal_ftruncate(map->fd, size);
+        VERBOSE("f%s-%s %zu, err %d", "truncate", "shrink", size, rc);
+      }
+      if (unlikely(rc != MDBX_SUCCESS))
         return rc;
       map->filesize = size;
     }
diff --git a/src/osal.h b/src/osal.h
index 7622d432..6202ff47 100644
--- a/src/osal.h
+++ b/src/osal.h
@@ -434,6 +434,7 @@ enum osal_syncmode_bits {
 
 MDBX_INTERNAL int osal_fsync(mdbx_filehandle_t fd, const enum osal_syncmode_bits mode_bits);
 MDBX_INTERNAL int osal_ftruncate(mdbx_filehandle_t fd, uint64_t length);
+MDBX_INTERNAL int osal_fallocate(mdbx_filehandle_t fd, uint64_t length);
 MDBX_INTERNAL int osal_fseek(mdbx_filehandle_t fd, uint64_t pos);
 MDBX_INTERNAL int osal_filesize(mdbx_filehandle_t fd, uint64_t *length);
 
@@ -470,7 +471,7 @@ MDBX_INTERNAL int osal_removedirectory(const pathchar_t *pathname);
 MDBX_INTERNAL int osal_is_pipe(mdbx_filehandle_t fd);
 MDBX_INTERNAL int osal_lockfile(mdbx_filehandle_t fd, bool wait);
 
-#define MMAP_OPTION_TRUNCATE 1
+#define MMAP_OPTION_SETLENGTH 1
 #define MMAP_OPTION_SEMAPHORE 2
 MDBX_INTERNAL int osal_mmap(const int flags, osal_mmap_t *map, size_t size, const size_t limit, const unsigned options,
                             const pathchar_t *pathname4logging);