diff --git a/tests/v1/kv_offload/test_fs_tier.py b/tests/v1/kv_offload/tiering/test_fs_tier.py
similarity index 100%
rename from tests/v1/kv_offload/test_fs_tier.py
rename to tests/v1/kv_offload/tiering/test_fs_tier.py
diff --git a/tests/v1/kv_offload/test_tiering_offloading.py b/tests/v1/kv_offload/tiering/test_tiering_offloading.py
similarity index 100%
rename from tests/v1/kv_offload/test_tiering_offloading.py
rename to tests/v1/kv_offload/tiering/test_tiering_offloading.py
diff --git a/vllm/v1/kv_offload/tiering/fs/manager.py b/vllm/v1/kv_offload/tiering/fs/manager.py
index c2bc720275..a33de02f43 100644
--- a/vllm/v1/kv_offload/tiering/fs/manager.py
+++ b/vllm/v1/kv_offload/tiering/fs/manager.py
@@ -52,6 +52,14 @@ class FileSystemTierManager(SecondaryTierManager):
     submit_store / submit_load are non-blocking: they enqueue tasks and return.
     get_finished_jobs() polls job completion and returns completed JobResults.
 
+    Cross-process sharing:
+        In order to enable KV cache sharing between multiple vLLM instances
+        using the same ``root_dir`` (e.g., via a shared PVC) the environment
+        variable ``PYTHONHASHSEED`` must be set to the same fixed value
+        (e.g., "0") on all instances. Without this, each process initializes
+        ``NONE_HASH`` (the chain-hash seed for block content hashes) with
+        random bytes, producing different block filenames for identical token
+        content.
     """
 
     def __init__(