diff --git a/java/com/google/gerrit/server/group/db/AuditLogReader.java b/java/com/google/gerrit/server/group/db/AuditLogReader.java
index fb58577..77e0e0c 100644
--- a/java/com/google/gerrit/server/group/db/AuditLogReader.java
+++ b/java/com/google/gerrit/server/group/db/AuditLogReader.java
@@ -27,7 +27,6 @@
 import com.google.gerrit.reviewdb.client.AccountGroupMemberAudit;
 import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.server.config.AllUsersName;
-import com.google.gerrit.server.config.GerritServerId;
 import com.google.gerrit.server.notedb.NoteDbUtil;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -51,12 +50,10 @@
 public class AuditLogReader {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
-  private final String serverId;
   private final AllUsersName allUsersName;
 
   @Inject
-  public AuditLogReader(@GerritServerId String serverId, AllUsersName allUsersName) {
-    this.serverId = serverId;
+  public AuditLogReader(AllUsersName allUsersName) {
     this.allUsersName = allUsersName;
   }
 
@@ -143,7 +140,7 @@
   }
 
   private Optional<ParsedCommit> parse(AccountGroup.UUID uuid, RevCommit c) {
-    Optional<Account.Id> authorId = NoteDbUtil.parseIdent(c.getAuthorIdent(), serverId);
+    Optional<Account.Id> authorId = NoteDbUtil.parseIdent(c.getAuthorIdent());
     if (!authorId.isPresent()) {
       // Only report audit events from identified users, since this was a non-nullable field in
       // ReviewDb. May be revisited.
@@ -179,7 +176,7 @@
   private Optional<Account.Id> parseAccount(AccountGroup.UUID uuid, RevCommit c, FooterLine line) {
     Optional<Account.Id> result =
         Optional.ofNullable(RawParseUtils.parsePersonIdent(line.getValue()))
-            .flatMap(ident -> NoteDbUtil.parseIdent(ident, serverId));
+            .flatMap(ident -> NoteDbUtil.parseIdent(ident));
     if (!result.isPresent()) {
       logInvalid(uuid, c, line);
     }
diff --git a/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java b/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
index 9cc1c84..10bae48 100644
--- a/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
+++ b/java/com/google/gerrit/server/notedb/AbstractChangeNotes.java
@@ -25,6 +25,7 @@
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.config.AllUsersName;
+import com.google.gerrit.server.config.GerritServerId;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.notedb.ChangeNotesCommit.ChangeNotesRevWalk;
 import com.google.gerrit.server.project.NoSuchChangeException;
@@ -51,6 +52,7 @@
     public final AllUsersName allUsers;
     public final LegacyChangeNoteRead legacyChangeNoteRead;
     public final NoteDbMetrics metrics;
+    public final String serverId;
 
     // Providers required to avoid dependency cycles.
 
@@ -64,7 +66,8 @@
         ChangeNoteJson changeNoteJson,
         LegacyChangeNoteRead legacyChangeNoteRead,
         NoteDbMetrics metrics,
-        Provider<ChangeNotesCache> cache) {
+        Provider<ChangeNotesCache> cache,
+        @GerritServerId String serverId) {
       this.failOnLoadForTest = new AtomicBoolean();
       this.repoManager = repoManager;
       this.allUsers = allUsers;
@@ -72,6 +75,7 @@
       this.changeNoteJson = changeNoteJson;
       this.metrics = metrics;
       this.cache = cache;
+      this.serverId = serverId;
     }
   }
 
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotes.java b/java/com/google/gerrit/server/notedb/ChangeNotes.java
index e1217c2..929974d 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotes.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotes.java
@@ -22,6 +22,7 @@
 
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableSet;
@@ -503,6 +504,19 @@
     ChangeNotesCache.Value v =
         args.cache.get().get(getProjectName(), getChangeId(), rev, handle::walk);
     state = v.state();
+
+    String stateServerId = state.serverId();
+    /**
+     * In earlier Gerrit versions serverId wasn't part of the change notes cache. That's why the
+     * earlier cached entries don't have the serverId attribute. That's fine because in earlier
+     * gerrit version serverId was already validated. Another approach to simplify the check would
+     * be to bump the cache version, but that would invalidate all persistent cache entries, what we
+     * rather try to avoid.
+     */
+    checkState(
+        Strings.isNullOrEmpty(stateServerId) || args.serverId.equals(stateServerId),
+        String.format("invalid server id, expected %s: actual: %s", args.serverId, stateServerId));
+
     state.copyColumnsTo(change);
     revisionNoteMap = v.revisionNoteMap();
   }
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
index 27c2aa6..b5087ff 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotesParser.java
@@ -135,6 +135,7 @@
   private Timestamp createdOn;
   private Timestamp lastUpdatedOn;
   private Account.Id ownerId;
+  private String serverId;
   private String changeId;
   private String subject;
   private String originalSubject;
@@ -223,6 +224,7 @@
         createdOn,
         lastUpdatedOn,
         ownerId,
+        serverId,
         branch,
         buildCurrentPatchSetId(),
         subject,
@@ -334,6 +336,10 @@
     Account.Id accountId = parseIdent(commit);
     if (accountId != null) {
       ownerId = accountId;
+      PersonIdent personIdent = commit.getAuthorIdent();
+      serverId = NoteDbUtil.extractHostPartFromPersonIdent(personIdent);
+    } else {
+      serverId = "UNKNOWN_SERVER_ID";
     }
     Account.Id realAccountId = parseRealAccountId(commit, accountId);
 
diff --git a/java/com/google/gerrit/server/notedb/ChangeNotesState.java b/java/com/google/gerrit/server/notedb/ChangeNotesState.java
index 2728516..5adc196 100644
--- a/java/com/google/gerrit/server/notedb/ChangeNotesState.java
+++ b/java/com/google/gerrit/server/notedb/ChangeNotesState.java
@@ -96,6 +96,7 @@
       Timestamp createdOn,
       Timestamp lastUpdatedOn,
       Account.Id owner,
+      String serverId,
       String branch,
       @Nullable PatchSet.Id currentPatchSetId,
       String subject,
@@ -154,6 +155,7 @@
                 .build())
         .pastAssignees(pastAssignees)
         .hashtags(hashtags)
+        .serverId(serverId)
         .patchSets(patchSets.entrySet())
         .approvals(approvals.entries())
         .reviewers(reviewers)
@@ -276,6 +278,9 @@
 
   abstract ImmutableSet<String> hashtags();
 
+  @Nullable
+  abstract String serverId();
+
   abstract ImmutableList<Map.Entry<PatchSet.Id, PatchSet>> patchSets();
 
   abstract ImmutableList<Map.Entry<PatchSet.Id, PatchSetApproval>> approvals();
@@ -376,6 +381,8 @@
 
     abstract Builder columns(ChangeColumns columns);
 
+    abstract Builder serverId(String serverId);
+
     abstract Builder pastAssignees(Set<Account.Id> pastAssignees);
 
     abstract Builder hashtags(Iterable<String> hashtags);
@@ -427,6 +434,10 @@
           .setChangeId(object.changeId().get())
           .setColumns(toChangeColumnsProto(object.columns()));
 
+      if (object.serverId() != null) {
+        b.setServerId(object.serverId());
+        b.setHasServerId(true);
+      }
       object.pastAssignees().forEach(a -> b.addPastAssignee(a.get()));
       object.hashtags().forEach(b::addHashtag);
       object
@@ -549,6 +560,7 @@
               .metaId(ObjectIdConverter.create().fromByteString(proto.getMetaId()))
               .changeId(changeId)
               .columns(toChangeColumns(changeId, proto.getColumns()))
+              .serverId(proto.getHasServerId() ? proto.getServerId() : null)
               .pastAssignees(
                   proto.getPastAssigneeList().stream().map(Account::id).collect(toImmutableSet()))
               .hashtags(proto.getHashtagList())
diff --git a/java/com/google/gerrit/server/notedb/LegacyChangeNoteRead.java b/java/com/google/gerrit/server/notedb/LegacyChangeNoteRead.java
index 36bfe47..7e301f7 100644
--- a/java/com/google/gerrit/server/notedb/LegacyChangeNoteRead.java
+++ b/java/com/google/gerrit/server/notedb/LegacyChangeNoteRead.java
@@ -50,14 +50,11 @@
 
   public Account.Id parseIdent(PersonIdent ident, Change.Id changeId)
       throws ConfigInvalidException {
-    return NoteDbUtil.parseIdent(ident, serverId)
+    return NoteDbUtil.parseIdent(ident)
         .orElseThrow(
             () ->
                 parseException(
-                    changeId,
-                    "invalid identity, expected <id>@%s: %s",
-                    serverId,
-                    ident.getEmailAddress()));
+                    changeId, "cannot retrieve account id: %s", ident.getEmailAddress()));
   }
 
   private static boolean match(byte[] note, MutableInteger p, byte[] expected) {
diff --git a/java/com/google/gerrit/server/notedb/NoteDbUtil.java b/java/com/google/gerrit/server/notedb/NoteDbUtil.java
index c53f4b9..bfbdd18 100644
--- a/java/com/google/gerrit/server/notedb/NoteDbUtil.java
+++ b/java/com/google/gerrit/server/notedb/NoteDbUtil.java
@@ -37,25 +37,28 @@
       ImmutableSet.of(
           "com.google.gerrit.httpd.restapi.RestApiServlet", RetryingRestModifyView.class.getName());
 
-  /**
-   * Returns an AccountId for the given email address. Returns empty if the address isn't on this
-   * server.
-   */
-  public static Optional<Account.Id> parseIdent(PersonIdent ident, String serverId) {
+  /** Returns an AccountId for the given email address. */
+  public static Optional<Account.Id> parseIdent(PersonIdent ident) {
     String email = ident.getEmailAddress();
     int at = email.indexOf('@');
     if (at >= 0) {
-      String host = email.substring(at + 1);
-      if (host.equals(serverId)) {
-        Integer id = Ints.tryParse(email.substring(0, at));
-        if (id != null) {
-          return Optional.of(Account.id(id));
-        }
+      Integer id = Ints.tryParse(email.substring(0, at));
+      if (id != null) {
+        return Optional.of(Account.id(id));
       }
     }
     return Optional.empty();
   }
 
+  public static String extractHostPartFromPersonIdent(PersonIdent ident) {
+    String email = ident.getEmailAddress();
+    int at = email.indexOf('@');
+    if (at >= 0) {
+      return email.substring(at + 1);
+    }
+    throw new IllegalArgumentException("No host part found: " + email);
+  }
+
   public static String formatTime(PersonIdent ident, Timestamp t) {
     GitDateFormatter dateFormatter = new GitDateFormatter(Format.DEFAULT);
     // TODO(dborowitz): Use a ThreadLocal or use Joda.
diff --git a/javatests/com/google/gerrit/server/group/db/AuditLogReaderTest.java b/javatests/com/google/gerrit/server/group/db/AuditLogReaderTest.java
index a5b755e..81108ea 100644
--- a/javatests/com/google/gerrit/server/group/db/AuditLogReaderTest.java
+++ b/javatests/com/google/gerrit/server/group/db/AuditLogReaderTest.java
@@ -37,7 +37,7 @@
 
   @Before
   public void setUp() throws Exception {
-    auditLogReader = new AuditLogReader(SERVER_ID, allUsersName);
+    auditLogReader = new AuditLogReader(allUsersName);
   }
 
   @Test
diff --git a/javatests/com/google/gerrit/server/notedb/ChangeNotesStateTest.java b/javatests/com/google/gerrit/server/notedb/ChangeNotesStateTest.java
index 3e54863..a4602e19 100644
--- a/javatests/com/google/gerrit/server/notedb/ChangeNotesStateTest.java
+++ b/javatests/com/google/gerrit/server/notedb/ChangeNotesStateTest.java
@@ -56,6 +56,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.UUID;
 import org.eclipse.jgit.lib.ObjectId;
 import org.junit.Before;
 import org.junit.Test;
@@ -66,6 +67,7 @@
       ObjectId.fromString("1234567812345678123456781234567812345678");
   private static final ByteString SHA_BYTES = ObjectIdConverter.create().toByteString(SHA);
   private static final String CHANGE_KEY = "Iabcdabcdabcdabcdabcdabcdabcdabcdabcdabcd";
+  private static final String DEFAULT_SERVER_ID = UUID.randomUUID().toString();
 
   private ChangeColumns cols;
   private ChangeColumnsProto colsProto;
@@ -717,6 +719,7 @@
             ImmutableMap.<String, Type>builder()
                 .put("metaId", ObjectId.class)
                 .put("changeId", Change.Id.class)
+                .put("serverId", String.class)
                 .put("columns", ChangeColumns.class)
                 .put("pastAssignees", new TypeLiteral<ImmutableSet<Account.Id>>() {}.getType())
                 .put("hashtags", new TypeLiteral<ImmutableSet<String>>() {}.getType())
@@ -918,6 +921,19 @@
                 .build());
   }
 
+  @Test
+  public void serializeServerId() throws Exception {
+    assertRoundTrip(
+        newBuilder().serverId(DEFAULT_SERVER_ID).build(),
+        ChangeNotesStateProto.newBuilder()
+            .setMetaId(SHA_BYTES)
+            .setChangeId(ID.get())
+            .setServerId(DEFAULT_SERVER_ID)
+            .setHasServerId(true)
+            .setColumns(colsProto.toBuilder())
+            .build());
+  }
+
   private static ChangeNotesStateProto toProto(ChangeNotesState state) throws Exception {
     return ChangeNotesStateProto.parseFrom(Serializer.INSTANCE.serialize(state));
   }
diff --git a/proto/cache.proto b/proto/cache.proto
index 77b6908..7e6abcc 100644
--- a/proto/cache.proto
+++ b/proto/cache.proto
@@ -186,6 +186,9 @@
 
   // Number of updates to the change's meta ref.
   int32 update_count = 19;
+
+  string server_id = 20;
+  bool has_server_id = 21;
 }