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Displaying posts with tag: Linux (reset)
Lock Down: Enforcing SELinux with Percona XtraDB Cluster

Why do I spend time blogging about security frameworks? Because, although there are some resources available on the Web, none apply to Percona XtraDB Cluster (PXC) directly. Actually, I rarely encounter a MySQL setup where SELinux is enforced and never when Percona XtraDB Cluster (PXC) or another Galera replication implementation is used. As we’ll see, there are good reasons for that. I originally thought this post would be a simple “how to” but it ended up with a push request to modify the SST script and a few other surprises.

Some context

These days, with all the major security breaches of the last few years, the importance of security in IT cannot be highlighted enough. For that reason, …

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MySQL Performance : IP port -vs- UNIX socket impact in 8.0 GA

Generally, when I'm analyzing MySQL Performance on Linux with "localhost" test workloads, I'm configuring client connections to use IP port (loopback) to connect to MySQL Server (and not UNIX socket) -- this is still at least involving IP stack in the game, and if something is going odd on IP, we can be aware ahead about. And indeed, it already helped several times to discover such kind of problems even without network links between client/server (like this one, etc.). However, in the past we also observed a pretty significant difference in QPS results when IP port was used comparing to UNIX socket (communications via UNIX socket were going near 15% faster).. Over a time with newer OL kernel releases this gap became smaller and smaller. But in all such …

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MySQL on Fedora 27

While updating my class image to Fedora 27, I noticed that it installed the Akonadi Server. The documentation on the Akonadi server lacked some straightforward documentation. It also offered a bundled set of software that limited how to approach MySQL development.

So, I removed all those packages with the following syntax:

dnf remove `rpm -qa | grep akonadi`

After removing those Akonadi packages, I installed the MySQL Community Edition from the Fedora repo with this syntax:

yum install -y community-mysql*

Having installed MySQL Community Edition, I started the service with this command:

sudo service mysql start

Then, I ran the mysql_secure_installation script to secure the installation:

mysql_secure_installation

The script set the root user’s password, remove the anonymous user, disallow remote root login, and …

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Restore data from InnoDB file (idb & frm) using TwinDB toolkit

We have been told many times that modifying live database should be done with extreme care, we should always make a backup before doing something big to the database. However, there are countless stories on the Internet about losing data due to various reason, one of them is forgetting to create a backup (Gitlab is an example: https://about.gitlab.com/2017/02/01/gitlab-dot-com-database-incident/). I was facing the same issue when upgrading MySQL server to a new version. Luckily I was able to restore most of the data but it was still a very good lesson for me. One of lesson I learned is how we could restore the data from the *.ibd and *.frm file.

The database I worked with had many tables. There were about 5 of them using MyISAM engine while others were using InnoDB engine. I was asked to upgrade …

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Tungsten Clustering 6.0 and Tungsten Replicator 6.0 are now available!

Continuent is very pleased and excited to announce that the new Tungsten Clustering 6.0 and Tungsten Replicator 6.0 are now available for download by our customers. The 6.0 release is the culmination of over a years work within our clustering product in order to improve the functionality and manageability of what we now call our ‘Multimaster Clustering’ solution. This is the replacement for what we called the multi-site, multi-master (MSMM) clustering functionality in earlier releases. The multimaster clustering allows for multiple clusters, in multiple locations, to be linked together into a single composite cluster. Because it’s a composite cluster, you gain all of the functionality that’s already available in a cluster, such as:

  • High availability
  • Failover
  • Automated recovery
  • Read-write split
  • Maintenance without downtime

But it’s now applied to the …

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Docker Compose Setup for InnoDB Cluster

In the following we show how InnoDB cluster can be deployed in a container context. In the official documentation (Introducing InnoDB Cluster), InnoDB is described as: MySQL InnoDB cluster provides a complete high availability solution for MySQL. MySQL Shell includes AdminAPI which enables you to easily configure and administer a group of at least three […]

Handling long duration SST(timeout) in PXC with systemd

In this blog post, We will be explaining about the timeouts in SST on systemd implementation which we faced recently in Percona XtraDB Cluster  during our Consulting with a client. State Snapshot Transfers (SST) refers to complete data sync from one of the nodes from the cluster to the joining node.

SST will happen for one or more reasons listed below.

  1. Initial sync to join a node to cluster.
  2. Node is out of cluster and lost its ability to join back due to data corruption or inconsistencies and also when the node went far behind the node, …
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How to convert galera node to async slave and vice-versa with MariaDB Galera Cluster.

Recently, I was working with one of our customer and this is what their requirement as they want to automate this process for converting galera node to async slave and make async slave to galera node without shutting down any server. ———- Here are the steps for how to do that. I assumes that you already have working 3 nodes galera cluster if not, then for the testing purpose you can create it from my previous post. setup-three-nodes-mariadb-galera-cluster-on-single-server-with-mysql-sandbox ———- Btw, there is no matter how many nodes you have. Now, create one test1 table and add 3 records in galera cluster.

MariaDB [nil]> select * from test1;
+------+-----------+
| id   | name      |
+------+-----------+
|    1 | nilnandan |
|    2 | joshi     |
|    3 | niljoshi  |
+------+-----------+ …
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Making Maxscale/ProxySQL Highly Available ( 2 > 1 )

As Mydbops we are implementing Load Balancer using Maxscale or ProxySQL ( Our presentation ) for lot our client,  but these load balancers will become a SPOF (Single Point of failure) .  We have tried to explore services like HAProxy, Nginx, and Keepalived etc. Except Keepalived, all the services need to run on the standalone instance and  did not satisfy our exact need.

Keepalived does not requires any standalone instance, it can be deployed and configured with a minimal effort and provide the HA Solutions to the DB Infra. This approach not only fits for our DB setup, we can implement same …

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CPU Utilization is Not a Useful Metric

Once upon a time CPU utilization was quite a useful metric. Following are the output of several tools that provide CPU utilization metrics:

top

top reports a load of 1.66.

Is this correct? No. The correct load number is probably closer to 2.4.

# top -b -n 1| head -20
top - 11:27:45 up 151 days,  1:55,  7 users,  load average: 1.66, 1.84, 1.88
Tasks: 389 total,   3 running, 386 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.7%us, 20.6%sy,  1.2%ni, 77.3%id,  0.1%wa,  0.0%hi,  0.1%si,  0.0%st
Mem:  32639636k total, 32206476k used,   433160k free,   235732k buffers
Swap: 16359420k total, 10285664k used,  6073756k free,  2354840k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
16702 root      20   0 8274m 5.0g 5.0g S 85.1 16.1  59164:55 VirtualBox
 4657 root      20   0  9.8g 5.2g 5.1g S 45.5 16.6  26518:13 VirtualBox
 6239 root      20   0  9.8g 5.1g 5.1g S 39.6 16.5  31200:52 VirtualBox
27070 root …
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