diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index b0e4395b2dd8..69eaebc18554 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -2972,8 +2972,8 @@ class LibvirtDriver(driver.ComputeDriver):
         fd = None
         try:
             fd = os.open(testfile, os.O_CREAT | os.O_WRONLY | os.O_DIRECT)
-            # Check is the write allowed with 512 byte alignment
-            align_size = 512
+            # Check is the write allowed with 4096 byte alignment
+            align_size = 4096
             m = mmap.mmap(-1, align_size)
             m.write(b"x" * align_size)
             os.write(fd, m)
diff --git a/releasenotes/notes/bug-1801702-c8203d3d55007deb.yaml b/releasenotes/notes/bug-1801702-c8203d3d55007deb.yaml
new file mode 100644
index 000000000000..67fa573c49b3
--- /dev/null
+++ b/releasenotes/notes/bug-1801702-c8203d3d55007deb.yaml
@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    When testing whether direct IO is possible on the backing storage
+    for an instance, Nova now uses a block size of 4096 bytes instead
+    of 512 bytes, avoiding issues when the underlying block device has
+    sectors larger than 512 bytes. See bug
+    https://launchpad.net/bugs/1801702 for details.