doc/geo-rep: Geo-rep Release notes - 3.7

Change-Id: I60afbbd597edcae002954a02fde3e632536fbfa3
Signed-off-by: Aravinda VK <avishwan@redhat.com>
Reviewed-on: http://review.gluster.org/10745
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 211 insertions, 0 deletions

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+### Improved Node fail-over issues handling by using Gluster Meta Volume
+
+In replica pairs one Geo-rep worker should be active and all
+the other replica workers should be passive. When Active worker goes
+down, Passive worker will become active. In previous releases, this logic
+was based on node-uuid, but now it is based on Lock file in Meta
+Volume. Now it is possible to decide Active/Passive more accurately
+and multiple Active worker scenarios minimized.
+
+Geo-rep works without Meta Volume also, this feature is backward
+compatible. By default config option `use_meta_volume` is False. This
+feature can be turned on with geo-rep config `use_meta_volume`
+true. Without this feature Geo-rep works as it was working in previous
+releases.
+
+Issues if meta_volume is turned off:
+
+1. Multiple workers becoming active and participate in
+syncing. Duplicate efforts and all the issues related to concurrent
+execution exists.
+
+2. Failover only works at node level, if a brick process goes down but
+node is alive then fail-back will not happen and delay in syncing.
+
+3. Very difficult documented steps about placements of bricks in case
+of replica 3. For example, first brick in each replica should not be
+placed in same node. etc.
+
+4. Consuming Changelogs from previously failed node when it comes
+back, which may lead to issues like delayed syncing and data
+inconsistencies in case of Renames.
+
+**Fixes**: [1196632](https://bugzilla.redhat.com/show_bug.cgi?id=1196632),
+[1217939](https://bugzilla.redhat.com/show_bug.cgi?id=1217939)
+
+
+### Improved Historical Changelogs consumption
+
+Support for consuming Historical Changelogs introduced in previous
+releases, with this release this is more stable and improved. Use of
+Filesystem crawl is minimized and limited only during initial sync.In
+previous release, Node reboot or brick process going down was treated as
+Changelog Breakage and Geo-rep was fallback to XSync for that
+duration. With this release, Changelog session will be considered
+broken only if Changelog is turned off. All the other scenarios
+considered as safe.
+
+This feature is also required by glusterfind.
+
+**Fixes**: [1217944](https://bugzilla.redhat.com/show_bug.cgi?id=1217944)
+
+
+### Improved Status and Checkpoint
+
+Status got many improvements, Showing accurate details of Session
+info, User info, Slave node to which master node is connected, Last
+Synced Time etc. Initializing time is reduced, Status change will
+happen as soon as geo-rep workers ready.(In previous releases
+Initializing time was 60 sec)
+
+**Fixes**: [1212410](https://bugzilla.redhat.com/show_bug.cgi?id=1212410)
+
+### Worker Restart improvements
+
+Workers going down and coming back is very common in geo-rep for
+reasons like network failure, Slave node going down etc. When it comes
+up it has to reprocess the changelogs again because worker died before
+updating the last sync time. The batch size is now optimized such that
+the amount of reprocess is minimized.
+
+**Fixes**: [1210965](https://bugzilla.redhat.com/show_bug.cgi?id=1210965)
+
+
+### Improved RENAME handling
+
+When renamed filename hash falls to other brick, respective brick's
+changelog records RENAME, but rest of the fops like CREATE, DATA are
+recorded in first brick. Each Geo-rep worker per brick syncs data to
+Slave Volume independently, These things go out of order and Master
+and Slave Volume become inconsistent. With the help of DHT team,
+RENAMEs are recorded where CREATE and DATA are recorded.
+
+**Fixes**: [1141379](https://bugzilla.redhat.com/show_bug.cgi?id=1141379)
+
+
+### Syncing xattrs and acls
+
+Syncing both xattrs and acls to Slave cluster are now supported. These
+can be disabled setting config options sync-xattrs or sync-acls to
+false.
+
+**Fixes**: [1187021](https://bugzilla.redhat.com/show_bug.cgi?id=1187021),
+[1196690](https://bugzilla.redhat.com/show_bug.cgi?id=1196690)
+
+
+### Identifying Entry failures
+
+Logging improvements to identify exact reason for Entry failures, GFID
+conflicts, I/O errors etc.  Safe errors are not logged in Mount logs
+in Slave, Safe errors are post processed and only genuine errors are
+logged in Master logs.
+
+**Fixes**: [1207115](https://bugzilla.redhat.com/show_bug.cgi?id=1207115),
+[1210562](https://bugzilla.redhat.com/show_bug.cgi?id=1210562)
+
+
+### Improved rm -rf issues handling
+
+Successive deletes and creates had issues, Handling these issues
+minimized. (Not completely fixed since it depends on Open issues of
+DHT)
+
+**Fixes**: [1211037](https://bugzilla.redhat.com/show_bug.cgi?id=1211037)
+
+
+### Non root Geo-replication simplified
+
+Manual editing of Glusterd vol file is simplified by introducing
+`gluster system:: mountbroker` command
+
+**Fixes**: [1136312](https://bugzilla.redhat.com/show_bug.cgi?id=1136312)
+
+### Logging Rsync performance on request basis
+
+Rsync performance can be evaluated by enabling a config option. After
+this Geo-rep starts recording rsync performance in log file, which can
+be post processed to get meaningful metrics.
+
+**Fixes**: [764827](https://bugzilla.redhat.com/show_bug.cgi?id=764827)
+
+### Initial sync issues due to upper limit comparison during Filesystem Crawl
+
+Bug fix, Fixed wrong logic in Xsync Change detection. Upper limit was
+considered during xsync crawl. Geo-rep XSync was missing many files
+considering Changelog will take care. But Changelog will not have
+complete details of the files created before enabling Geo-replication.
+
+When rsync/tarssh fails, geo-rep is now capable of identifying safe
+errors and continue syncing by ignoring those issues. For example,
+rsync fails to sync a file which is deleted in master during
+sync. This can be ignored since the file is unlinked and no need to
+try syncing.
+
+**Fixes**: [1200733](https://bugzilla.redhat.com/show_bug.cgi?id=1200733)
+
+
+### Changelog failures and Brick failures handling
+
+When Brick process goes down, or any Changelog exception Geo-rep
+worker was failing back to XSync crawl. Which was bad since Xsync
+fails to identify Deletes and Renames. Now this is prevented, worker
+goes to Faulty and wait for that Brick process to comeback.
+
+
+**Fixes**: [1202649](https://bugzilla.redhat.com/show_bug.cgi?id=1202649)
+
+
+### Archive Changelogs in working directory after processing
+
+Archive Changelogs after processing not generate empty changelogs when
+no data is available. This is great improvement in terms of reducing
+the inode consumption in Brick.
+
+**Fixes**: [1169331](https://bugzilla.redhat.com/show_bug.cgi?id=1169331)
+
+
+### Virtual xattr to trigger sync
+
+Since we use Historical Changelogs when Geo-rep worker restarts. Only
+`SETATTR` will be recorded when we touch a file. In previous versions,
+Re triggering a file sync is stop geo-rep, touch files and start
+geo-replication. Now touch will not help since it records only `SETATTR`.
+Virtual Xattr is introduced to retrigger the sync. No Geo-rep restart
+required.
+
+**Fixes**: [1176934](https://bugzilla.redhat.com/show_bug.cgi?id=1176934)
+
+
+### SSH Keys overwrite issues during Geo-rep create
+
+Parallel creates or multiple Geo-rep session creation was overwriting
+the pem keys written by first one. This leads to connectivity issues
+when Geo-rep is started.
+
+**Fixes**: [1183229](https://bugzilla.redhat.com/show_bug.cgi?id=1183229)
+
+
+### Ownership sync improvements
+
+Geo-rep was failing to sync ownership information from master cluster
+to Slave cluster.
+
+**Fixes**: [1104954](https://bugzilla.redhat.com/show_bug.cgi?id=1104954)
+
+
+### Slave node failover handling improvements
+
+When slave node goes down, Master worker which is connected to that
+brick will go to faulty. Now it tries to connect to another slave node
+instead of waiting for that Slave node to come back.
+
+**Fixes**: [1151412](https://bugzilla.redhat.com/show_bug.cgi?id=1151412)
+
+
+### Support of ssh keys custom location
+
+If ssh `authorized_keys` are configured in non standard location instead
+of default `$HOME/.ssh/authorized_keys`. Geo-rep create was failing, now
+this is supported.
+
+**Fixes**: [1181117](https://bugzilla.redhat.com/show_bug.cgi?id=1181117)