It’s time for the weekly roundup of news for Percona Server and XtraBackup. To follow up on my note from last week, we’re still checking and validating the download stats. It appears that Percona Server has been downloaded well over 100,000 times, and Percona XtraBackup has been downloaded over 200,000 times. But when we changed the script to separate out the downloads for our 5.5 release series, the overall number came back slightly decreased, which makes no sense. We haven’t had the chance to vet the analysis script yet, but we should be able to do that shortly.

For Percona Server,

• We worked on Solaris builds for the server.
• Peter proposed a feature for the server to enable more efficient incremental backups with XtraBackup.
• Peter, Vadim, and Nickolay continued investigating alternative methods of implementing flush in Percona Server. (I am involved, but not as deeply.) The task is complex and …

This is a test to see if people will vote this down on Planet MySQL. If you’ll vote down some of the posts that have gotten negative marks recently, like Allan Packer saying that he’s still working on Sparc supercluster, or Drizzle going GA, or Percona Server and XtraBackup being available on Solaris, or mk-query-digest filter how-tos, or TokuDB announcing online add of columns, or XtraBackup Manager, or using WordPress on Drizzle, well…

Most people looking at a diagram showing the Cluster architecture soon want to know if the system can scale online. Api nodes such as MySQLD processes can be added online, and the storage capacity of existing data nodes can be increased online, but it was not always possible to add new data nodes to the cluster without an initial system restart requiring a backup and restore.

An online add node and data repartitioning feature was finally implemented in MySQL Cluster 7.0. It's not clear how often users actually do scale their Clusters online, but it certainly is a cool thing to be able to do.

There are two parts to the feature :

1. Online add an empty data node to an existing cluster
2. Online rebalance existing data across the existing and new data nodes

Adding an empty data node to a cluster sounds trivial, but is actually fairly complex given the cluster's …

In the following article I have summarized some steps and hints to set-up a MySQL active/passive fail-over Cluster also sometimes called MySQL HA.

With such a set-up you can achieve a 99.99% (4x9) HA set-up for MySQL (52 minutes downtime per year). The same procedure also works for PostgreSQL, Oracle and other database systems running on Linux (DRBD runs on Linux only).

The concept

The concept of an active/passive fail-over Cluster is the following:

• You have 2 servers (also called nodes).
• They communicate over a cluster software (Heartbeat, Corosync, OpenAIS, Red Hat Cluster Suite).
• They are running on …

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It's now been 12 months since Oracle absorbed Sun. A lot has happened in that time, and the good news is that Sun's technology has a new lease on life. Reviewing my blog entries over the last 2 or 3 years, most of them were focussed on MySQL and T-series systems. Lots of good things are happening with both product lines.

As for me, I've been working on SPARC Supercluster. More on this topic later... ;-)

It's now been 12 months since Oracle absorbed Sun. A lot has happened in that time, and the good news is that Sun's technology has a new lease on life. Reviewing my blog entries over the last 2 or 3 years, most of them were focussed on MySQL and T-series systems. Lots of good things are happening with both product lines.

As for me, I've been working on SPARC Supercluster. More on this topic later... ;-)

It's now been 12 months since Oracle absorbed Sun. A lot has happened in that time, and the good news is that Sun's technology has a new lease on life. Reviewing my blog entries over the last 2 or 3 years, most of them were focussed on MySQL and T-series systems. Lots of good things are happening with both product lines.

As for me, I've been working on SPARC Supercluster. More on this topic later... ;-)

The FromDual Performance Monitor for MySQL has now a new module for monitoring DRBD. Since more an more of our customers want to run MySQL High Availability solutions based on DRBD we have implemented this module.

We gather all information which are reported with the command:

# cat /proc/drbd

version: 8.3.8 (api:88/proto:86-94)
 0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r----
    ns:1241240 nr:14311680 dw:15033532 dr:1241281 al:198 bm:52 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0

Now you can easily find the DRBD version which is installed on your systems, the connection state, the role, the disk state and the used protocol of your DRBD device.

Further we have added graphs for network and disk traffic and for internal data structure activity.

When DRBD is down we will rise an alert:

The new DRBD module is included in the Version v0.6 of our MySQL …

MySQL Cluster distributes rows amongst the data nodes in a cluster, and also provides data replication. How does this work? What are the trade offs?

Table fragments

Tables are 'horizontally fragmented' into table fragments each containing a disjoint subset of the rows of the table. The union of rows in all table fragments is the set of rows in the table. Rows are always identified by their primary key. Tables with no primary key are given a hidden primary key by MySQLD.

By default, one table fragment is created for each data node in the cluster at the time the table is created.

Node groups and Fragment replicas

The data nodes in a cluster are logically divided into Node groups. The size of each Node group is controlled by the NoOfReplicas parameter. All data nodes in a Node group store the same data. In other words, where the NoOfReplicas parameter is two or greater, each …