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14 votes
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How to restart MariaDB Galera cluster?

MariaDB Galera Cluster: Solution 1: 1) I've changed safe_to_bootstrap parameter to 1 on one of the node in the file /var/lib/mysql/grastate.dat: safe_to_bootstrap: 1 2) After that I killed all mysql ...
Oleksandr's user avatar
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8 votes
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How to recover MariaDB Galera Cluster after full crash?

Pre-Recovery Settings: Ensure that the MYSQL_HOME path is being exported in the .profile. If the MySQL install is in a different location, then make that change to the MYSQL_HOME.(Example: MYSQL_HOME=...
Siero Sierikas's user avatar
6 votes
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MariaDB 10.1.16 on Ubuntu fails to start: WSREP Failed to recover position

There was a bug in galera_recovery.sh script. https://jira.mariadb.org/browse/MDEV-10396
Nirbhay Choubey's user avatar
6 votes

Galera cluster into Google cloud platform

but I have difficulties to see the added value compared to Cloud SQL instances with replication and backup. I am not very familiar in scaling heavy load systems. Galera-based clusters like ...
MarcosAlbe's user avatar
5 votes
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How to verify galera is synced

If wsrep_local_state_comment, wsrep_ready, and wsrep_connected show the correct values, then that particular node is good. There's no Seconds_Behind_Master equivalent, because Galera is synchronous ...
Michael - sqlbot's user avatar
5 votes
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ERROR WSREP`: gcs/src/gcs.cpp:gcs_open():1379:` Failed to open channel 'test_cluster'

We should start the first node without below parameter in my.cnf : wsrep_cluster_address="gcomm://192.168.120.107,192.168.120.111,192.168.120.117" Then start the other nodes normally : /etc/init....
amir jj's user avatar
  • 289
5 votes
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'kill <thread id>' gives ERROR 1095 (HY000): You are not owner of thread ... even though I am

The error message is misleading. Galera can mark user threads as high priority which means they can't be killed. Currently, this gives the ERROR 1095 (HY000): You are not owner of thread... See MDEV-...
dbdemon's user avatar
  • 6,301
4 votes

ERROR WSREP`: gcs/src/gcs.cpp:gcs_open():1379:` Failed to open channel 'test_cluster'

Please bootstrap the first node with below option service mysql start --wsrep-new-cluster Make sure you have the settings below in all config files: wsrep_cluster_address="gcomm://192.168.120.107,...
user134461's user avatar
4 votes
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Stop INNODB MONITOR OUTPUT

The variable you're looking for is innodb_status_output. Setting it to OFF should stop the innodb status from being dumped into the error log.
G-Nugget's user avatar
  • 688
4 votes
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100x less insert performance with Galera multi-master

I've hit the same issue. The first thing to do is to check the following variables: select @@innodb_flush_log_at_trx_commit; select @@sync_binlog; Setting innodb_flush_log_at_trx_commit to 2 and ...
Ilshat Karazbayev's user avatar
4 votes
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Percona - Unable to start mysql after restart

Yes Rick is right. Because all of nodes are down you have to bootstrap Cluster again. You stopped all nodes gracefully. If you know What is the last one (node) stopped, choice this node too ...
HamoonDBA's user avatar
  • 617
4 votes
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what is MDL? (e.g. 'MDL semantics' or 'MDL locks') Probably Galera related

It stands for "MetaData Locking" seeing the sources of MySQL https://dev.mysql.com/doc/dev/mysql-server/8.0.0/mdl_8h.html It's a way to keep an ACID database by avoiding concurrent access to the same ...
Xenos's user avatar
  • 195
3 votes

MySQL cluster write performance with Galera (MariaDB)

Data Warehousing (your app) and OLTP are somewhat different. So, I question the relevancy of the benchmark. OLTP, if I am not mistaken, involves very short 'transactions', which can suffer from the ...
Rick James's user avatar
  • 77.6k
3 votes

The right way of starting up a Galera Cluster

At MariaDB 10.1 where Galera included you need to start first node with key --wsrep-new-cluster e.g. /etc/init.d/mysql start --wsrep-new-cluster All other nodes starts as usually: /etc/init.d/mysql ...
Roman Bogachev's user avatar
3 votes

How to get number of active users with one SQL-Query?

I don't know how to translate your tables into any of n_active_users; n_users_created_classified; n_user_sent_msg; n_user_read_msg. But here are some clues: A simple query for the immediately ...
Rick James's user avatar
  • 77.6k
3 votes

What are the drawbacks of using Galera Cluster instead of Master/Slave Replication?

Some drawbacks of Galera include: Storage engine support: limited to InnoDB/XtraDB (plus experimental support for MyISAM) OS support: only Linux/Unix-like Oses There are also some limitations which ...
dbdemon's user avatar
  • 6,301
3 votes

Is Galera Arbitrator really required?

If you have minimum of three active nodes in your cluster, you don't need to add garbd. You should use a garbd with the following conditions: When you have an even number of nodes and you can't add ...
HamoonDBA's user avatar
  • 617
3 votes
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Is it safe to disable sync_binlogs, innodb_flush_log_at_trx_commit and innodb_doublewrite on a site-redundant galera cluster?

I've done some research on this now, so I'll answer on my own question. Summary first If the performance problems are observed only on one node, it's perfectly safe to turn off innodb_doublewrite ...
tobixen's user avatar
  • 211
3 votes

100x less insert performance with Galera multi-master

While Galera can work correctly in multi-master use, it still means that the "certification" at commit must check all conflicts. If you insert records into the same table at multiple nodes, such ...
Jörg Brühe's user avatar
3 votes

How to perform backup on quite active 500G+ MariaDB Galera Cluster?

Plan A: Using just the nodes of the cluster: take a node out of the cluster: SET GLOBAL wsrep_desync = ON; SET GLOBAL wsrep_on = OFF; (See wsrep_desync and wsrep_on.) back it up via Xtrabackup (or ...
Rick James's user avatar
  • 77.6k
3 votes
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Galera SST fails

wsrep_sst_donor=2.2.2.2 wsrep_sst_donor should have the node name, not the IP address. A similar case was reported in the MariaDB Jira as MDEV-13687.
dbdemon's user avatar
  • 6,301
3 votes
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Galera not working with Replication

Your node2 needs to have log-slave-updates=1. See also SeveralNines' article on the topic which states: log-slaves-updates=1 is necessary for the writes to propagate from the slave to the other ...
dbdemon's user avatar
  • 6,301
3 votes
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MySQL Galera Cluster mass update delay

Galera replication is not synchronous, only what they call 'virtually synchronous'. It's synchronous only up to the point where the write set is to be applied. There might be a small period of time ...
dbdemon's user avatar
  • 6,301
3 votes
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MySQL XtraDB/Galera Cluster High Availability RamDisk *SuperFast*

OK, 3 Galera nodes, with: Each having all disk stuff sitting in RAM disks. Enough RAM to make that possible. The nodes separated geographically so that a volcano, flood, etc, cannot take out all of ...
Rick James's user avatar
  • 77.6k
3 votes
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MySQL PXC node failing to receive state

First of all, thanks for providing enough debug information, not everybody does that. Your SST (data copy) is failing. Apparently, netcat is failing with "no route to host" error- that tells you that ...
jynus's user avatar
  • 14.8k
3 votes
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mysql_insert_id() on galera mysql cluster

The "insert_id" is local to the connection. No locking is needed to get the value. This applies in all flavors of multi-processing, clustering, engines, etc. Still, you may need "transactions" for ...
Rick James's user avatar
  • 77.6k
3 votes

single node stuck in WSREP has not yet prepared node for application use

I met this issue too, and solved it by re-sync that node through SST. I use RSYNC as SST method to make sure the consistence between nodes.
Sender's user avatar
  • 31
3 votes
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How Can I Find the Problems Occurred on MySQL-MariadbDB Systems?

You should look at the MariaDB error log. The authoritative documentation on this is found in the MariaDB Knowledgebase: Error Log. If you're using Ubuntu, then I assume you have systemd, which means ...
dbdemon's user avatar
  • 6,301
2 votes

WSREP: failed to report last committed and stop

warning WSREP: Failed to report last committed This is just a warning, and in itself isn't a cause for concern. I think it's unlikely that this caused the node to stop. See also Percona's blog post ...
dbdemon's user avatar
  • 6,301
2 votes
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MariaDB/Galera Cluster with 3 nodes - Change ENGINE from MyISAM to InnoDB without crash

I need the tables to be InnoDB and in sync. Those two statements crashing. Does it crash with a stack trace in the server logs? Could you share it here? I tried the above two commands on a 2-node ...
Nirbhay Choubey's user avatar

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