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Displaying posts with tag: Yves Trudeau (reset)
Q&A: High availability when using MySQL in the cloud

Last week I hosted a webinar on using MySQL in the cloud for High Availability (HA) alongside 451 Research analyst Jason Stamper. You can watch the recording and also download the slides (free) here. Just click the “Register” button at the end of that page.

We had several excellent questions and we didn’t have time to get to several of them in the allotted time. I’m posting them here along with the answers. Feel free to ask follow-up questions in the comments below.

Q: Can the TokuDB engine be used in a PXC environment?

A: No, TokuDB cannot currently be used in a PXC environment, the only supported engine in …

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Update on the InnoDB double-write buffer and EXT4 transactions

In a post, written a few months ago, I found that using EXT4 transactions with the “data=journal” mount option, improves the write performance significantly, by 55%, without putting data at risk. Many people commented on the post mentioning they were not able to reproduce the results and thus, I decided to further investigate in order to find out why my results were different.

So, I ran sysbench benchmarks on a few servers and found when the InnoDB double-write buffer limitations occur and when they don’t. I also made sure some of my colleagues were able to reproduce the results. Basically, in order to reproduce the results you need the following conditions:

  • Spinning disk (no SSD)
  • Enough CPU power
  • A dataset that fits in the InnoDB buffer pool
  • A continuous high write …
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MaxScale: A new tool to solve your MySQL scalability problems

Ever since MySQL replication has existed, people have dreamed of a good solution to automatically split read from write operations, sending the writes to the MySQL master and load balancing the reads over a set of MySQL slaves. While if at first it seems easy to solve, the reality is far more complex.

First, the tool needs to make sure it parses and analyses correctly all the forms of SQL MySQL supports in order to sort writes from reads, something that is not as easy as it seems. Second, it needs to take into account if a session is in a transaction or not.

While in a transaction, the default transaction isolation level in InnoDB, Repeatable-read, and the MVCC framework insure that you’ll get a consistent view for the duration of the transaction. That means all statements executed inside a transaction must run on the master but, when the transaction commits or rollbacks, the following select statements on the session can be again …

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New in Percona Replication Manager: Slave resync, Async stop

Percona Replication Manager (PRM) continues to evolve and improve, I want to introduce two new features: Slave resync and Async stop.

Slave resync

This behavior is for regular non-gtid replication.  When a master crashes and is no longer available, how do we make sure all the slaves are in a consistent state. It is easy to find the most up to date slave and promote it to be the new master based on the master execution position, the PRM agent already does that but how do we apply the missing transactions to the other slaves.

In order to solve that problem, I modified a tool originally written by Yelp, that outputs the MD5 sums of the payload (XID boundaries) and the commit positions of a binlog file. It produces an output like:

root@yves-desktop:/home/yves/src/PRM/percona-pacemaker-agents/tools/prm_binlog_parser# ./prm_binlog_parser.static.x86_64 /opt/prm/binlog.000382 | tail -n 5 …
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Exploring message brokers

Message brokers are not regularly covered here but are, nonetheless, important web-related technologies. Some time ago, I was asked by one of our customer to review a selection of OSS message brokers and propose a couple of good candidates. The requirements were fairly simple: behave well when there’s a large backlog of messages, be able to create a cluster and in case of the failure of a node in a cluster, try to protect the data but never blocks the publishers even though that might imply data lost. Nothing fancy regarding queues and topics management. I decided to write my findings here, before I forget…

I don’t consider myself a message broker specialist and I spent only about a day or two on each so, I may have done some big mistakes configuration wise. I’ll take the blame if something is misconfigured or not used correctly.

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Percona Replication Manager (PRM) now supporting 5.6 GTID

Over the last few days, I integrated the MySQL 5.6 GTID version of the Percona Replication Manager (PRM) work of Frédéric Descamps, a colleague at Percona. The agent supports the GTID replication mode of MySQL 5.6 and if the master suffers a hard crash, it picks the slave having applied the highest transaction ID from the dead master. Given the nature of GTID-based replication, that causes all the other slaves to resync appropriately to their new master which is pretty cool and must yet be matched by the regular PRM agent.

For now, it is part of a separate agent, mysql_prm56, which may be integrated with the regular agent in the future. To use it, download the agent with the link above, the pacemaker configuration is similar to the one of the regular PRM agent. If you start from scratch, have a look …

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How to add VIPs to Percona XtraDB Cluster or MHA with Pacemaker

It is a rather frequent problem to have to manage Virtual IP addresses (VIPs) with a Percona XtraDB Cluster (PXC) or with MySQL master HA (MHA). In order to help solving these problems, I wrote a Pacemaker agent, mysql_monitor that is a simplified version of the mysql_prm agent. The mysql_monitor agent only monitors MySQL and set attributes according to the state of MySQL, the read-only variable, the slave status and/or the output of the clustercheck script for PXC. The agent can operate in 3 modes or cluster types: replication (default), pxc and read-only.

The simplest mode is read-only, only the state of the read_only variable is looked at. If the node has the read_only variable set to OFF, then the writer is set to 1 and reader attributes is set to 1 while if the node has read_only set to ON, the writer attributes will …

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LVM read performance during snapshots

For the same customer I am exploring ZFS for backups, the twin server is using regular LVM and XFS. On this twin, I have setup mylvmbackup for a more conservative backup approach. I quickly found some odd behaviors, the backup was taking much longer than what I was expecting. It is not the first time I saw that, but here it was obvious. So I recorded some metrics, bi from vmstat and percent of cow space used from lvs during a backup. Cow space is the Copy On Write buffer used by LVM to record the modified pages like they were at the beginning of the snapshot. Upon reads, LVM must scan the list to verify that there’s no newer version. Here’s the other details about the backup:

  • Filesystem: 2TB, xfs
  • Snapsize: 60GB
  • Amount to backup: ~600GB
  • Backup tool: mylvmbackup
  • Compressor: pbzip2

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Percona welcomes Yves Trudeau and Fernando Ipar

I'm happy to extend a warm welcome to two new members of the Percona team.

First is Yves Trudeau, about whom I can say many things:

  • One of the top MySQL Cluster (NDB Cluster) experts in the world.
  • An expert on all things High Availability, including DRBD and Heartbeat.
  • Many years of experience with Huge Data.
  • Half of the Waffle Grid team.
  • A really nice person!

Yves joins us after a tenure of several years as a senior consultant at Sun/MySQL. Together with Matt Yonkovit, he plans to work on WaffleGrid (but as a new project under a new name, to be determined), and integration with XtraDB. Yves lives in Quebec with his family.

Next is Fernando Ipar. Fernando is our first dedicated Shift Support Captain[1]. Fernando specializes in MySQL, GNU/Linux, systems administration, and high availability. Fernando has been involved in computer programming since …

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Showing entries 1 to 9