diff --git a/nexus/db-model/src/schema_versions.rs b/nexus/db-model/src/schema_versions.rs
index ad80039d57c..9fcc215496b 100644
--- a/nexus/db-model/src/schema_versions.rs
+++ b/nexus/db-model/src/schema_versions.rs
@@ -16,7 +16,7 @@ use std::{collections::BTreeMap, sync::LazyLock};
 ///
 /// This must be updated when you change the database schema.  Refer to
 /// schema/crdb/README.adoc in the root of this repository for details.
-pub const SCHEMA_VERSION: Version = Version::new(309, 0, 0);
+pub const SCHEMA_VERSION: Version = Version::new(310, 0, 0);
 
 /// List of all past database schema versions, in *reverse* order
 ///
@@ -28,6 +28,7 @@ pub static KNOWN_VERSIONS: LazyLock<Vec<KnownVersion>> = LazyLock::new(|| {
         // |  leaving the first copy as an example for the next person.
         // v
         // KnownVersion::new(next_int, "unique-dirname-with-the-sql-files"),
+        KnownVersion::new(310, "add-unadopted-sled-and-rack-tables"),
         KnownVersion::new(309, "fm-certificate-de"),
         KnownVersion::new(308, "inv-power-shelf-psu"),
         KnownVersion::new(307, "add-rack-id-to-inv-sled-agent"),
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up01.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up01.sql
new file mode 100644
index 00000000000..438337dcd7c
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up01.sql
@@ -0,0 +1,21 @@
+-- Tracks other racks that have joined the underlay network but haven't been
+-- adopted into the multirack cluster.
+--
+-- If/when a rack is adopted, its row in this table should be marked deleted,
+-- and a corresponding row should be inserted into the `rack` table.
+CREATE TABLE IF NOT EXISTS omicron.public.unadopted_rack (
+    -- This should be the same id that gets used for the `rack` table, as well
+    -- as the `rack_id` column in `unadopted_sled`:
+    id UUID PRIMARY KEY,
+
+    time_created TIMESTAMPTZ NOT NULL,
+    time_modified TIMESTAMPTZ NOT NULL,
+    time_deleted TIMESTAMPTZ,
+
+    -- The IPv6 underlay /56 prefix for the rack:
+    rack_subnet INET NOT NULL,
+
+    -- Underlay address of the particular sled-agent instance on the unadopted
+    -- rack that's running the multirack join service:
+    join_service_ip INET NOT NULL
+);
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up02.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up02.sql
new file mode 100644
index 00000000000..36e8eaa5ded
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up02.sql
@@ -0,0 +1,34 @@
+-- Tracks sleds from other racks that have joined the underlay network but
+-- haven't been adopted into the multirack cluster.
+--
+-- If/when these sleds are adopted, these rows should be marked deleted, and
+-- there will subsequently be corresponding rows created in the `sled` and
+-- `inv_sled_agent` tables via the normal mechanisms.
+CREATE TABLE IF NOT EXISTS omicron.public.unadopted_sled (
+    id UUID PRIMARY KEY,
+    -- Foreign key into the `unadopted_rack` table (though, also, the rack ID
+    -- that gets used in the `rack` table should be the same if/when the rack
+    -- is adopted)
+    rack_id UUID NOT NULL,
+
+    time_created TIMESTAMPTZ NOT NULL,
+    time_modified TIMESTAMPTZ NOT NULL,
+    time_deleted TIMESTAMPTZ,
+
+    -- Baseboard information about the sled
+    serial_number STRING(63) NOT NULL,
+    part_number STRING(63) NOT NULL,
+
+    sled_agent_ip INET NOT NULL,
+
+    -- This tracks whether this particular sled's sled-agent has been
+    -- successfully started by the multirack join service:
+    sled_agent_started BOOL NOT NULL,
+    -- This nullable column should be set to the last error we've seen for this
+    -- particular sled's sled-agent startup process, if any:
+    last_start_error_seen TEXT,
+
+    CONSTRAINT start_error_is_null_if_started CHECK (
+        (NOT sled_agent_started) OR (last_start_error_seen IS NULL)
+    )
+);
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up03.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up03.sql
new file mode 100644
index 00000000000..55a678732fd
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up03.sql
@@ -0,0 +1,3 @@
+CREATE UNIQUE INDEX IF NOT EXISTS lookup_unadopted_rack_by_id ON omicron.public.unadopted_rack (
+    id
+) WHERE time_deleted IS NULL;
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up03.verify.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up03.verify.sql
new file mode 100644
index 00000000000..109627899aa
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up03.verify.sql
@@ -0,0 +1,2 @@
+-- DO NOT EDIT. Generated by test_migration_verification_files.
+SELECT CAST(IF((SELECT true WHERE EXISTS (SELECT index_name FROM omicron.crdb_internal.table_indexes WHERE descriptor_name = 'unadopted_rack' AND index_name = 'lookup_unadopted_rack_by_id')),'true','Schema change verification failed: index lookup_unadopted_rack_by_id on table unadopted_rack does not exist') AS BOOL);
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up04.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up04.sql
new file mode 100644
index 00000000000..b35285c83ee
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up04.sql
@@ -0,0 +1,3 @@
+CREATE UNIQUE INDEX IF NOT EXISTS lookup_unadopted_sled_by_id ON omicron.public.unadopted_sled (
+    id
+) WHERE time_deleted IS NULL;
diff --git a/schema/crdb/add-unadopted-sled-and-rack-tables/up04.verify.sql b/schema/crdb/add-unadopted-sled-and-rack-tables/up04.verify.sql
new file mode 100644
index 00000000000..957185e5e74
--- /dev/null
+++ b/schema/crdb/add-unadopted-sled-and-rack-tables/up04.verify.sql
@@ -0,0 +1,2 @@
+-- DO NOT EDIT. Generated by test_migration_verification_files.
+SELECT CAST(IF((SELECT true WHERE EXISTS (SELECT index_name FROM omicron.crdb_internal.table_indexes WHERE descriptor_name = 'unadopted_sled' AND index_name = 'lookup_unadopted_sled_by_id')),'true','Schema change verification failed: index lookup_unadopted_sled_by_id on table unadopted_sled does not exist') AS BOOL);
diff --git a/schema/crdb/dbinit.sql b/schema/crdb/dbinit.sql
index 695be128c8b..92742f3b6d4 100644
--- a/schema/crdb/dbinit.sql
+++ b/schema/crdb/dbinit.sql
@@ -9730,6 +9730,70 @@ CREATE TABLE IF NOT EXISTS omicron.public.fm_config (
     )
 );
 
+-- Tracks other racks that have joined the underlay network but haven't been
+-- adopted into the multirack cluster.
+--
+-- If/when a rack is adopted, its row in this table should be marked deleted,
+-- and a corresponding row should be inserted into the `rack` table.
+CREATE TABLE IF NOT EXISTS omicron.public.unadopted_rack (
+    -- This should be the same id that gets used for the `rack` table, as well
+    -- as the `rack_id` column in `unadopted_sled`:
+    id UUID PRIMARY KEY,
+
+    time_created TIMESTAMPTZ NOT NULL,
+    time_modified TIMESTAMPTZ NOT NULL,
+    time_deleted TIMESTAMPTZ,
+
+    -- The IPv6 underlay /56 prefix for the rack:
+    rack_subnet INET NOT NULL,
+
+    -- Underlay address of the particular sled-agent instance on the unadopted
+    -- rack that's running the multirack join service:
+    join_service_ip INET NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS lookup_unadopted_rack_by_id ON omicron.public.unadopted_rack (
+    id
+) WHERE time_deleted IS NULL;
+
+-- Tracks sleds from other racks that have joined the underlay network but
+-- haven't been adopted into the multirack cluster.
+--
+-- If/when these sleds are adopted, these rows should be marked deleted, and
+-- there will subsequently be corresponding rows created in the `sled` and
+-- `inv_sled_agent` tables via the normal mechanisms.
+CREATE TABLE IF NOT EXISTS omicron.public.unadopted_sled (
+    id UUID PRIMARY KEY,
+    -- Foreign key into the `unadopted_rack` table (though, also, the rack ID
+    -- that gets used in the `rack` table should be the same if/when the rack
+    -- is adopted)
+    rack_id UUID NOT NULL,
+
+    time_created TIMESTAMPTZ NOT NULL,
+    time_modified TIMESTAMPTZ NOT NULL,
+    time_deleted TIMESTAMPTZ,
+
+    -- Baseboard information about the sled
+    serial_number STRING(63) NOT NULL,
+    part_number STRING(63) NOT NULL,
+
+    sled_agent_ip INET NOT NULL,
+
+    -- This tracks whether this particular sled's sled-agent has been
+    -- successfully started by the multirack join service:
+    sled_agent_started BOOL NOT NULL,
+    -- This nullable column should be set to the last error we've seen for this
+    -- particular sled's sled-agent startup process, if any:
+    last_start_error_seen TEXT,
+
+    CONSTRAINT start_error_is_null_if_started CHECK (
+        (NOT sled_agent_started) OR (last_start_error_seen IS NULL)
+    )
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS lookup_unadopted_sled_by_id ON omicron.public.unadopted_sled (
+    id
+) WHERE time_deleted IS NULL;
 
 -- Keep this at the end of file so that the database does not contain a version
 -- until it is fully populated.
@@ -9740,7 +9804,7 @@ INSERT INTO omicron.public.db_metadata (
     version,
     target_version
 ) VALUES
-    (TRUE, NOW(), NOW(), '309.0.0', NULL)
+    (TRUE, NOW(), NOW(), '310.0.0', NULL)
 ON CONFLICT DO NOTHING;
 
 COMMIT;