Documentation/public-inbox-index.pod  | 5 +++--
 Documentation/public-inbox-tuning.pod | 6 ++++--

diff --git a/Documentation/public-inbox-index.pod b/Documentation/public-inbox-index.pod
index 207b2ed863f05933af57264c3801e7b83abbc58c..936516f808eaa52b15b4248a2ea91317cfbfae8d 100644
--- a/Documentation/public-inbox-index.pod
+++ b/Documentation/public-inbox-index.pod
@@ -129,8 +129,9 @@ below.
 
 When using rotational storage but abundant RAM, using a large
 value (e.g. C<500m>) with C<--sequential-shard> can
-significantly speed up the initial index and full C<--reindex>
-invocations (but not incremental updates).
+significantly speed up and reduce fragmentation during the
+initial index and full C<--reindex> invocations (but not
+incremental updates).
 
 Available in public-inbox 1.6.0 (PENDING).
 
diff --git a/Documentation/public-inbox-tuning.pod b/Documentation/public-inbox-tuning.pod
index b4e7698bcca975a972921216128d74225cb222f9..f5a25676b7aab830b91c5679fd13e70041b10b28 100644
--- a/Documentation/public-inbox-tuning.pod
+++ b/Documentation/public-inbox-tuning.pod
@@ -74,7 +74,7 @@ sharding imposes a performance penalty for read-only queries.
 
 Users with large amounts of RAM are advised to set a large value
 for C<publicinbox.indexBatchSize> as documented in
-L<public-inbox-config(5)>.
+L<public-inbox-index(1)>.
 
 C<dm-crypt> users on Linux 4.0+ are advised to try the
 C<--perf-same_cpu_crypt> C<--perf-submit_from_crypt_cpus>
@@ -95,7 +95,9 @@
 Fortunately, these SQLite and Xapian indices are designed to
 recoverable from git if missing.
 
-Disabling CoW does not prevent all fragmentation.
+Disabling CoW does not prevent all fragmentation.  Large values
+of C<publicInbox.indexBatchSize> also limit fragmentation during
+the initial index.
 
 Avoid snapshotting subvolumes containing Xapian and/or SQLite indices.
 Snapshots use CoW despite our efforts to disable it, resulting