January 5, 2015 By Severalnines

Cloud storage is hot. Dropbox, Apple iCloud, Google Drive, Microsoft SkyDrive and Amazon Cloud Drive all offer cloud sharing platforms where you can store documents in the cloud and access them from all your devices. For enterprises who require full control, ownCloud is an open source solution that allows files to be stored on-premises and/or a backend cloud. 

In this blog post, we’ll show you how to deploy a high availability setup using ownCloud Community Edition. We will need to set up redundancy in each of the following layers:

• file storage
• web server
• database server
• load balancer

We will use five servers. ownCloud will run on three separate servers with MySQL Galera Cluster 5.6 and GlusterFS running on RHEL 6.5 64bit. ownCloud supports GlusterFS as primary storage. ClusterControl will be co-located …

Query caching is one of the prominent features in MySQL and a vital part of query optimization. It is important to know how it works as it has the potential to cause significant performance improvements – or a slowdown – of your workload.

The MySQL query cache is a global one shared among the sessions. It caches the select query along with the result set, which enables the identical selects to execute faster as the data fetches from the in memory. It is important to have everything identical, no new comments, spaces, or most significantly differences in the WHERE clause. Basically when you trigger a select query, if it is available in the cache; it fetches from there or it considers the query as a new one and will go to the parser.

Even though it has some nice advantages, the MySQL query cache has its own downsides too. Well, let’s think about this: If you are frequently updating the table, you are then invalidating …

So assume you just uploaded the certificate you use to identify yourself to the MySQL server to Github or some other place it doesn't belong...and there is no undelete.

First: Don't panic.
Often a password is required besides a certificate to connect to the server. So someone with the certificate can't use it without the password. The certificate itself might be protected by a password, but that's really rare. Also access to MySQL and/or your account should be limited to certain IP's.

The next step is to revoke the certificate. This is possible since MySQL 5.6.3 by using a Certificate Revocation List (CRL).
A CRL is a list of the serials of the revoked certificates and signed by the CA. So this will only work if the certificates have unique serials.
…

At the last OOW MySQL Plugin for Oracle Enterprise Manager (OEM) was recognized as most popular MySQL product. If you don't have OEM installed, but want to test the plugin you can download OEM virtual box template. But, althought this is the easiest way to get started, you still need to make few additions. At least I had to do them when deployed such installation for MySQL Support Team.

Here they are. I prefer to use command line when possible.

0. Import virtual machine image and change network adapter to working one, then allow to connections via rdesktop:

sudo vboxmanage import VBox_EM12cR4.ova --vsys 0 --vmname  …

If you’ve been studying complex systems you know what minor changes might cause consequences of much greater proportions, sometimes causing some effects that are not easily explained at first. I recently ran across a great illustration of such behavior while doing MySQL benchmarks which I thought would be interesting to share.

I’m using a very simple benchmark – Sysbench 0.5 on Percona Server 5.6.21-70.1 just running update queries:

sysbench  --num-threads=64 --report-interval=10 --max-time=0 --max-requests=0 --rand-type=pareto --oltp-table-size=1000000000 --mysql-user=root --mysql-password= --mysql-db=sbinnodb  --test=/usr/share/doc/sysbench/tests/db/update_index.lua run

Some people frown upon such benchmarks due to their triviality and being irrelevant to workloads. I like them because they often allow you to study already complex system behavior in a much more controlled environment than “real” workloads – and so …

In this post ,we mainly talk about MHA GTID behavior, we test different cases and find something is different from previous versions .

we have four machines for this test.

environment:

master server: 10.0.128.77
slave server : 10.0.128.110/113/114
port : 3306 

————————————————————————————–

we first do normal failover .

kill master server

we find MHA outputs:

Tue Dec 30 13:32:14 2014 - [warning] Got error on MySQL connect ping: DBI connect(';host=10.0.128.77;port=3306;mysql_connect_timeout=1','dbadmin',...) failed: Lost connection to MySQL server at 'reading initial communication packet', system error: 111 at /usr/share/perl5/vendor_perl/MHA/HealthCheck.pm line 97
2013 (Lost connection to MySQL server at 'reading initial communication packet', system error: 111)
Tue Dec 30 13:32:14 2014 - [info] Executing secondary network check …

State Snapshot Transfer (SST) is used in Percona XtraDB Cluster (PXC) when a new node joins the cluster or to resync a failed node if Incremental State Transfer (IST) is no longer available. SST is triggered automatically but there is no magic: If it is not configured properly, it will not work and new nodes will never be able to join the cluster. Let’s have a look at a few classic issues.

Port for SST is not open

The donor and the joiner communicate on port 4444, and if the port is closed on one side, SST will always fail.

You will see in the error log of the donor that SST is started:

[...]
141223 16:08:48 [Note] WSREP: Node 2 (node1) requested state transfer from '*any*'. Selected 0 (node3)(SYNCED) as donor.
141223 16:08:48 [Note] WSREP: Shifting SYNCED -> DONOR/DESYNCED (TO: 6)
141223 16:08:48 …

Check Out Our Latest Technical Resources for MySQL, MariaDB & MongoDB Clusters

Like every month this year, we have created new content and tools for you; here is a summary of what we’ve published this December. Please do check it out and let us know if you have any comments or feedback.

And thank you for following us in the past 12 months and for your fidelity; we look forward to “seeing” you next year as well and wish you a great start to 2015!

New Live Technical Webinars

Infrastructure automation isn’t easy, but it’s not rocket science either, says Riaan Nolan. Riaan has been in operations for the past decade, and has built over a dozen eCommerce …

Some time ago, Peter Zaitsev posted a blog titled “How well does your table fits in innodb buffer pool?” He used some special INFORMATION_SCHEMA tables developed for Percona Server 5.1 to report how much of each InnoDB table and index resides in your buffer pool.

As Peter pointed out, you can use this view into the buffer pool to watch a buffer pool warm up with pages as you run queries. You can also use it for capacity planning. If you expect some tables need to be fully loaded in the buffer pool to be used efficiently, but the buffer pool isn’t large enough to hold them, then it’s time to increase the size of the buffer pool.

The problem, however, was that system tables change from version to version. Specifically, the INNODB_BUFFER_POOL_PAGES_INDEX table no longer exists in Percona Server 5.6, and the …

I helped a charity to rebuild a MySQL server and to restore a database with a lot of data of longblob type in the last two days. Fortunately there was a dump backup file for the database in question.

However, tables with longblob column(s) were not defined with “ROW_FORMAT=COMPRESSED”. I’d like to restore that database with row compression before inserting the data. Therefore I need to modify the dump sql file. The problem is that the file is 2.5 GB and the server only has 4 GB memory. So editing it is a challenge. Fortunately, Linux has sed to save the day. Don’t you love open source free software?

I am power Vi/Vim user, so I am familiar with sed and have used it in the past. But there are still a few things that I searched around for quick answers. So I’ll record noteworthy points here. I couldn’t remember how many times my own past blog entries helped me over the years. And I hope you’ll find this helpful too! …