The fsfreeze command, is used to suspend and resume access to a file system. This allows consistent snapshots to be taken of the filesystem. fsfreeze supports Ext3/4, ReiserFS, JFS and XFS.

A filesystem can be frozen using following command:

# /sbin/fsfreeze -f /data

Now if you are writing to this filesystem, the process/command will be stuck. For example, following command will be stuck in D (UNINTERUPTEBLE_SLEEP) state:

# echo “testing” > /data/file

Only after the filesystem is unfreezed using the following command, can it continue:

# /sbin/fsfreeze -u /data

As per the fsfreeze main page, “fsfreeze is unnecessary for device-mapper devices. The device-mapper (and LVM) automatically freezes filesystem on the device when a snapshot creation is requested.”

fsfreeze is provided by the util-linux package in RHEL systems. Along with userspace support, fsfreeze also …

First of all a disclaimer: I don’t work for Oracle nor do I speak for them. I believe this information to be correct, but for licensing questions, Oracle themselves have the final word.

With that out of the way, followers of this blog may have seen some of the results from my testing of actual CPU capacity with public clouds like Amazon Web Services, Microsoft Azure, and Google Compute Engine. In each of these cases, a CPU “core” was actually measured to be equivalent to an x86 HyperThread, or half a physical core. So when provisioning public cloud resources, it’s important to include twice as many CPU cores as the equivalent …

In Mo’ Data, Mo’ Problems, we explored the paradox that “Big Data” projects pose to organizations and how Tokutek is taking an innovative approach to solving those problems. In this post, we’re going to talk about another hot topic in IT, “The Cloud,” and how enterprises undertaking Cloud efforts often struggle with idea of “problem trading.” Also, for some reason, databases are just given a pass as traditionally “noisy neighbors” and that there is nothing that can be done about it. Lets take a look at why we disagree.

With the birth of the information age came a coupling of business and IT. Increasingly strategic business projects and objectives were reliant on information infrastructure to provide information storage and retrieval instead of paper and filing cabinets. This was the dawn of the database and what gave rise to companies like Oracle, Sybase and MySQL. With the appearance of true Enterprise Grade …

Join 29,000 others and follow Sean Hull on twitter @hullsean. Can RDS worsen an outage ?? That’s another way to think about this question. In my experience, it very clearly increases outages, by tying one or both hands behind your back. Believe me when I say, that is terribly frustrating when you’re putting out fires! […]

February 4, 2015 By Severalnines Check Out Our Latest Technical Resources for MySQL, MariaDB & MongoDB Clusters

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

New Live Technical Webinars

A DevOps Guide to Database Infrastructure Automation for eCommerce

Tuesday, February 17th

Infrastructure automation isn’t easy, but it’s not rocket science either, says Riaan Nolan. Automation is a worthwhile investment for retailers serious about eCommerce, but deciding on which …

Mydumper is known as the faster (much faster) mysqldump alternative. So, if you take a logical backup you will choose Mydumper instead of mysqldump. But what about the restore? Well, who needs to restore a logical backup? It takes ages! Even with Myloader. But this could change just a bit if we are able to take advantage of Fast Index Creation.

As you probably know, Mydumper and mysqldump export the struct of a table, with all the indexes and the constraints, and of course, the data. Then, Myloader and MySQL import the struct of the table and import the data. The most important difference is that you can configure Myloader to import the data using a certain amount of threads. The import steps are:

1. Create the complete struct of the table
2. Import the data

When you execute Myloader, internally it first creates the tables executing the “-schema.sql” files and then takes all the filenames …

Background on Backup Locks

I was very excited to see Backup locks support in release notes for the latest Percona XtraDB Cluster 5.6.21 release. For those who are not aware, backup locks offer an alternative to FLUSH TABLES WITH READ LOCK (FTWRL) in Xtrabackup. While Xtrabackup can hot-copy Innodb, everything else in MySQL must be locked (usually briefly) to get a consistent snapshot that lines up with Innodb. This includes all other storage engines, but also things like table schemas (even on Innodb) and async replication binary logs. You can skip this lock, but it isn’t …

Thanks to everyone who attended and participated in last week’s webinar on 'Galera Cluster for MySQL vs MySQL (NDB) Cluster: A High Level Comparison'. If you missed the sessions or would like to watch the webinar again & browse through the slides, they are now available online.

In this webinar, Severalnines VP of Products, Alex Yu, who was part of the team at Ericsson who originally developed the NDB storage engine in 2001, gave an overview of the two clustering architectures and discussed their respective strengths and weaknesses: 

1. MySQL Cluster architecture: strengths and limitations
2. Galera Architecture: strengths and limitations
3. Deployment scenarios
4. Data migration
5. Read and write workloads (Optimistic/pessimistic locking)
6. WAN/Geographical replication
7. Schema changes
8. Management and monitoring …

Amazon recently announced RDS Aurora a new addition to their database as a service offerings. Here’s Mark Callaghan’s take on what’s happening under the hood and thoughts from Fusheng Han. Amazon is uniquely positioned with RDS to take on offerings like Clustrix. So it’s definitely worth reading Dave Anselmi’s take on Aurora. Join 28,000 others […]

One of the big announcements at the Amazon Web Services re:Invent 2014 conference this week was the unveiling of Aurora. The result of years of internal work, Aurora, currently in preview, is a MySQL 5.6-compatible option that “combines the speed and availability of high-end commercial databases with the simplicity and cost-effectiveness of open source databases” on the AWS infrastructure. The Aurora database engine will be made available through the Amazon RDS for Aurora service. This new database option is another example of the vibrant innovation coming from the MySQL ecosystem and key role that relational databases play in applications of today and …