Update XDCR compatibility matrix for 8-0 (#3953)

Author: rao-shwe

modules/learn/pages/buckets-memory-and-storage/vbuckets.adoc

@@ -24,6 +24,8 @@ The number of vBuckets depends on the bucket's storage backend (the system that
 * Buckets that use the Couchstore storage engine use 1024 vBuckets on Linux and Windows.
 * Buckets that use Magma storage engine can use either 128 or 1024 vBuckets on Linux and Windows.
 You choose the number of vBuckets when you create the bucket.
+If you're using XDCR, review the xref:learn:clusters-and-availability/xdcr-overview.adoc#xdcr-compatibility[XDCR Compatibility] information
+on vBuckets for Server versions earlier than 8.0.
 
 The system distributes vBuckets evenly across the memory and storage resources of nodes that run the xref:services-and-indexes/services/data-service.adoc[Data Service].
 The bucket's data is distributed evenly across its vBuckets.

modules/learn/pages/clusters-and-availability/xdcr-enable-crossclusterversioning.adoc

@@ -12,6 +12,26 @@ Therefore, you must not enable `enableCrossClusterVersioning` casually.
 When you set the bucket property `enableCrossClusterVersioning` (ECCV) to `true`, for each document processed by XDCR, XDCR stores additional metadata for the document in the extended attributes.
 This metadata is also called Hybrid Logical Vector (HLV), which is a set of Hybrid Logical Clock (HLC) information.
 
+[NOTE]
+====
+Cross Cluster Versioning (ECCV) Compatibility with Couchbase Server Versions::
+
+Starting in Couchbase Server 7.6.6, buckets include the `enableCrossClusterVersioning` (ECCV) property, which is set to `false` (disabled) by default.
++
+If you set ECCV to `true` (enabled) on a bucket in an XDCR replication topology,
+then you must set ECCV to `true` on all buckets participating in the XDCR replication topology.
+Otherwise, dependent features may not function.
++
+As the Couchbase Server versions earlier than 7.6.6 do not support the `enableCrossClusterVersioning` bucket property,
+those buckets cannot participate in a replication topology containing ECCV-enabled buckets.
++
+XDCR does not automatically validate ECCV property consistency across buckets.
+If you want to prevent a bucket without ECCV from participating in an XDCR replication topology, then before creating or modifying XDCR replications,
+you must manually verify that ECCV is disabled for all participating buckets.
++
+For more information about XDCR compatibility between different versions of Couchbase Server Enterprise edition, see xref:learn:clusters-and-availability/xdcr-overview.adoc#xdcr-compatibility[XDCR Compatibility].
+====
+
 [#hlv-data-maintained-in-xattr]
 == Hybrid Logical Vector (HLV) Data Maintained in the Extended Attributes
 

modules/learn/pages/clusters-and-availability/xdcr-overview.adoc

@@ -267,7 +267,7 @@ If either a source or a target bucket needs to be flushed after a replication ha
 [#xdcr-and-bucket-expiration]
 == XDCR and Expiration
 
-Buckets, collections, and documents have a _TTL_ setting, which determines the maximum expiration times of individual items.
+Buckets, collections, and documents have a TTL setting, which determines the maximum expiration times of individual items.
 This is explained in detail in xref:learn:data/expiration.adoc[Expiration].
 For specific information on how TTL is affected by XDCR, see the section xref:learn:data/expiration.adoc#bucket-expiration-and-xdcr[Expiration and XDCR].
 
@@ -278,65 +278,87 @@ Detailed information is provided in xref:manage:manage-xdcr/monitor-xdcr-replica
 
 [#xdcr-compatibility]
 == XDCR Compatibility
+[.edition]#{enterprise}#
 
-The following table indicates XDCR compatibility between different versions of Couchbase Enterprise Server, used for source and target clusters.
+The following table indicates XDCR compatibility between different versions of Couchbase Server Enterprise edition, used for source and target clusters.
 
-[cols="6,3,3,3,3,3,3"]
+[cols="4,4,4,4"]
 |===
 | *Enterprise Server Version*
-| *7.6.x*
-| *7.2.x*
-| *7.1.4*, *7.1.3*, *7.1.2*, *7.1.1*
-| *7.1.0*
-| *7.0.x*
-| *6.6.x*
-
-| 7.6.x
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
+| *8.0.x*
+| *7.6.6 and later versions*
+| *7.6.5*, *7.6.4*, *7.6.3*, *7.6.2*, *7.6.1*, *7.6.0*, *7.2.x*, *7.1.x*, *7.0.x*
 
-| 7.2.x
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
+| 8.0.x
 | ✓
+| ✓*
+| ✓**
 
-| 7.1.4, 7.1.3, 7.1.2, 7.1.1
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
+No ECCV
 
-| 7.1.0
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
-| ❌
+| 7.6.6 and later
+| ✓*
+| ✓*
+| ✓**
 
-| 7.0.x
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
-| ✓
+No ECCV
 
-| 6.6.x
-| ✓
-| ✓
-| ✓
-| ❌
-| ✓
+| 7.6.5, 7.6.4, 7.6.3, 7.6.2, 7.6.1, 7.6.0, 7.2.x, 7.1.x, 7.0.x
+| ✓**
+
+No ECCV
+| ✓**
+
+No ECCV
 | ✓
 
 |===
+
+[NOTE]
+====
+XDCR Compatibility with vBucket Configuration (for both * and **)::
+
+Starting in Couchbase Server 8.0, Magma storage backend buckets can have either 128 or 1024 vBuckets.
+In earlier versions, all buckets had 1024 vBuckets, except on macOS.
++
+When creating XDCR replications between the Couchbase Server clusters, make sure of the compatibility of number of vBuckets with the Couchbase Server version as follows:
+
++
+--
+* From pre-8.0 to 8.0:
++
+The source and destination buckets must have the same number of vBuckets.
+For example, when replicating from a 7.x cluster to an 8.x cluster, create the target 8.x bucket with 1024 vBuckets.
+
+* From 8.0 to pre-8.0:
++
+The vBucket counts do not need to match.
+However, the vBucket count mismatch, in the source and target buckets of an XDCR topology, does not support the bi-directional replication.
+
+* Between 8.0 and later versions:
++
+Replications are supported even if the buckets have different vBucket counts.
+--
++
+For more information about Magma storage, see xref:learn:buckets-memory-and-storage/storage-engines.adoc[Storage Engines].
++
+For more information about vBuckets, see xref:learn:buckets-memory-and-storage/vbuckets.adoc[vBuckets].
+
+
+Cross Cluster Versioning (ECCV) Compatibility (for ** only)::
+
+Starting in Couchbase Server 7.6.6, buckets include the `enableCrossClusterVersioning` (ECCV) property, which is set to `false` (disabled) by default.
++
+If you set ECCV to `true` (enabled) on a bucket in an XDCR replication topology,
+then you must set ECCV to `true` on all buckets participating in the XDCR replication topology.
+Otherwise, dependent features may not function.
++
+As the Couchbase Server versions earlier than 7.6.6 do not support the `enableCrossClusterVersioning` bucket property,
+those buckets cannot participate in a replication topology containing ECCV-enabled buckets.
++
+XDCR does not automatically validate ECCV property consistency across buckets.
+If you want to prevent a bucket without ECCV from participating in an XDCR replication topology, then before creating or modifying XDCR replications,
+you must manually verify that ECCV is disabled for all participating buckets.
++
+For more information about ECCV, see xref:learn:clusters-and-availability/xdcr-enable-crossclusterversioning.adoc[XDCR enableCrossClusterVersioning].
+====