diff --git a/src/api-env.c b/src/api-env.c
index a1878cc3..78251213 100644
--- a/src/api-env.c
+++ b/src/api-env.c
@@ -1118,13 +1118,16 @@ __cold int mdbx_env_set_geometry(MDBX_env *env, intptr_t size_lower, intptr_t si
   }
 
   const size_t unit_ps = (globals.sys_pagesize > (size_t)pagesize) ? globals.sys_pagesize : (size_t)pagesize;
-  const size_t unit_ag = (globals.sys_allocation_granularity > unit_ps) ? globals.sys_allocation_granularity : unit_ps;
+  const size_t unit_ag = (globals.sys_allocation_granularity > unit_ps &&
+                          (growth_step < 0 || (size_t)growth_step >= globals.sys_allocation_granularity))
+                             ? globals.sys_allocation_granularity
+                             : unit_ps;
   size_lower = ceil_powerof2(size_lower, unit_ps);
   size_upper = ceil_powerof2(size_upper, unit_ag);
   size_now = ceil_powerof2(size_now, unit_ag);
 
   /* LY: подбираем значение size_upper:
-   *  - кратное размеру страницы
+   *  - кратное размеру unit_ag (размеру страницы БД и системному размеру выделения)
    *  - без нарушения MAX_MAPSIZE и MAX_PAGENO */
   while (unlikely((size_t)size_upper > MAX_MAPSIZE || (uint64_t)size_upper / pagesize > MAX_PAGENO + 1)) {
     if ((size_t)size_upper < unit_ag + MIN_MAPSIZE || (size_t)size_upper < (size_t)pagesize * (MIN_PAGENO + 1)) {
diff --git a/src/dxb.c b/src/dxb.c
index 28520e0c..6206f0f2 100644
--- a/src/dxb.c
+++ b/src/dxb.c
@@ -570,7 +570,7 @@ __cold int dxb_setup(MDBX_env *env, const int lck_rc, const mdbx_mode_t mode_bit
 
   size_t expected_filesize = 0;
   const size_t used_bytes = pgno2bytes(env, header.geometry.first_unallocated);
-  const size_t used_aligned2os_bytes = ceil_powerof2(used_bytes, globals.sys_pagesize);
+  const size_t used_aligned2os_bytes = ceil_powerof2(used_bytes, globals.sys_allocation_granularity);
   if ((env->flags & MDBX_RDONLY)    /* readonly */
       || lck_rc != MDBX_RESULT_TRUE /* not exclusive */
       || /* recovery mode */ env->stuck_meta >= 0) {
@@ -843,13 +843,13 @@ __cold int dxb_setup(MDBX_env *env, const int lck_rc, const mdbx_mode_t mode_bit
   if (lck_rc == /* lck exclusive */ MDBX_RESULT_TRUE) {
     //-------------------------------------------------- shrink DB & update geo
     /* re-check size after mmap */
-    if ((env->dxb_mmap.current & (globals.sys_pagesize - 1)) != 0 || env->dxb_mmap.current < used_bytes) {
+    if (floor_powerof2(env->dxb_mmap.current, globals.sys_pagesize) < used_bytes) {
       ERROR("unacceptable/unexpected datafile size %" PRIuPTR, env->dxb_mmap.current);
       return MDBX_PROBLEM;
     }
     if (env->dxb_mmap.current != env->geo_in_bytes.now) {
-      header.geometry.now = bytes2pgno(env, env->dxb_mmap.current);
-      NOTICE("need update meta-geo to filesize %" PRIuPTR " bytes, %" PRIaPGNO " pages", env->dxb_mmap.current,
+      header.geometry.now = bytes2pgno(env, env->geo_in_bytes.now);
+      NOTICE("need update meta-geo to filesize %" PRIuPTR " bytes, aligned %" PRIaPGNO " pages", env->geo_in_bytes.now,
              header.geometry.now);
     }
 
diff --git a/src/osal.c b/src/osal.c
index 199d2cc2..711a4477 100644
--- a/src/osal.c
+++ b/src/osal.c
@@ -3517,7 +3517,8 @@ void osal_ctor(void) {
   SYSTEM_INFO si;
   GetSystemInfo(&si);
   globals.sys_pagesize = si.dwPageSize;
-  globals.sys_allocation_granularity = si.dwAllocationGranularity;
+  globals.sys_allocation_granularity =
+      (si.dwAllocationGranularity > globals.sys_pagesize) ? si.dwAllocationGranularity : globals.sys_pagesize;
 #else
   globals.sys_pagesize = sysconf(_SC_PAGE_SIZE);
   globals.sys_allocation_granularity = (MDBX_WORDBITS > 32) ? 65536 : 16384;
@@ -3533,8 +3534,9 @@ void osal_ctor(void) {
       globals.sys_allocation_granularity = globals.sys_unified_cache_block;
   }
 #endif /* AT_UCACHEBSIZE */
-
 #endif
+  if (globals.sys_allocation_granularity > 4 * MEGABYTE && globals.sys_pagesize < MEGABYTE)
+    globals.sys_allocation_granularity = 4 * MEGABYTE;
   assert(globals.sys_pagesize > 0 && (globals.sys_pagesize & (globals.sys_pagesize - 1)) == 0);
   assert(globals.sys_allocation_granularity >= globals.sys_pagesize &&
          globals.sys_allocation_granularity % globals.sys_pagesize == 0);