Adding upstream version 1.44.3.upstream/1.44.3

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/health/guides/redis/redis_master_link_down.md b/health/guides/redis/redis_master_link_down.md
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+### Understand the alert
+
+The `redis_master_link_down` alert is triggered when there is a disconnection between a Redis master and its slave for more than 10 seconds. This alert indicates a potential problem with the replication process and can impact the data consistency across multiple instances.
+
+### Troubleshoot the alert
+
+1. Check the Redis logs
+
+   Examine the Redis logs for any errors or issues regarding the disconnection between the master and slave instances. By default, Redis log files are located at `/var/log/redis/redis.log`. Look for messages related to replication, network errors or timeouts.
+
+   ```
+   grep -i "replication" /var/log/redis/redis.log
+   grep -i "timeout" /var/log/redis/redis.log
+   ```
+
+2. Check the Redis replication status
+
+   Connect to the Redis master using the `redis-cli` tool, and execute the `INFO` command to get the detailed information about the master instance:
+
+   ```
+   redis-cli
+   INFO REPLICATION
+   ```
+
+   Also, check the replication status on the slave instance. If you have access to the IP address and port of the slave, connect to it and run the same `INFO` command.
+
+3. Verify the network connection between the master and slave instances
+
+   Test the network connectivity using `ping` and `telnet` or `nc` commands, ensuring that the connection between the master and slave instances is stable and there are no issues with firewalls or network policies.
+
+   ```
+   ping <slave_ip_address>
+   telnet <slave_ip_address> <redis_port>
+   ```
+
+4. Restart the Redis instances (if needed)
+
+   If Redis instances are experiencing issues or are unable to reconnect, consider restarting them. Be cautious as restarting instances might result in data loss or consistency issues.
+
+   ```
+   sudo systemctl restart redis
+   ```
+
+5. Monitor the situation
+
+   After addressing the potential issues, keep an eye on the Redis instances to ensure that the problem doesn't reoccur.
+
+### Useful resources
+
+1. [Redis Replication Documentation](https://redis.io/topics/replication)