Oracle DynDNS with Booth Geo-Clustering

Pacemaker was never designed to operate across the WAN, or any high latency networks. However, there has always been a need and desire to orchestrate active/passive failovers between data centers and across long distances. To address this issue the Booth Pacemaker add-on was conceived back in late 2011. LINBIT has been involved in the development of Booth since 2013, and has been offering it as a supported solution since 2015.

Booth addresses the shortcomings of Pacemaker by introducing the concept of “tickets”. We constrain particular resources to tickets, and only the site which holds the ticket may start the particular resources. This can be thought of like the old token ring networks of days past. In order for Booth to ensure there is no cluster split, and two sites never possess the ticket at the same time, we utilize arbitration nodes to achieve quorum, and set an expiration period upon the tickets. If a site loses communication with the rest of the Booth cluster its ticket will not renew and it will stop resources within the expected time frame.

While Pacemaker with Booth addresses the issues of High Availability across the WAN, one issue which has always proven difficult is redirecting client traffic to the new site. In most of our demonstrations of Booth we have simply used a round-robin DNS (such as in my demonstration here: Booth Geo Cluster Demo). While round-robin DNS is easy to configure and simple, it is quite inefficient as every other request is discarded.

LINBIT has recently been working with Oracle DynDNS in order to find a more efficient and better solution. Fortunately, Oracle DynDNS offers a Managed DNS service toting a feature aptly named, “Active Failover”. The Active Failover feature can be configured to monitor several things for health. The managed Oracle DynDNS servers can monitor an IP address via ping, SMTP, HTTP(S) or a particular listening TCP port, and then update the DNS destinations only when the service fails and Pacemaker switches the sites. This makes it much more efficient and a perfect match for Pacemaker clusters utilizing Booth.

To demonstrate this solution in detail we have developed a tech-guide which outlines, step-by-step, how to configure this using RHEL 7, Pacemaker, Booth, and Oracle DynDNS Managed DNS, to provide a Highly Available, Geo-Clustered, MariaDB service. This document can be found in the documentation section of our website at the link below.

https://www.linbit.com/en/resources/102-disaster-recovery/geo-clustering-drbd-8-rhel-7/

Would you want to be your own car mechanic?

Data seems to be on everyone’s mind these days.  From employee to financial data, your company has to keep it available through seamless replication — without downtime. LINBIT DRBD is the open source software that ensures High Availability for your enterprise.

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Red Hat Summit KeyNote: How to survive rapid change – Jim Whitehurst

In Jim Whitehurst’s Red Hat Summit 2017 keynote, he opened by making a bold claim: planning is dead. He followed up his statement with predictions from the past that have turned out to be grossly inaccurate. He referred to a prominent example from 1899 when the US Patent office stated that “Everything that can be invented has been invented,” a quote that received soft laughs from the audience of 10,000.

 

Following the claim that traditional planning is dead, Jim backed it up with a statement of fact when he stated that “cognitive bias makes us terrible at predicting the future. The faster the rate of change, the worse we are at planning.” So, how do companies succeed if they can’t plan linearly? Both companies and people are fighting to keep pace with change, and change is coming from every direction. For example: how would car manufacturers have planned for Uber? Uber came out of nowhere with a few dollars of venture funding. Now, car companies are building their businesses around providing cars for new-age taxi services like Uber. No doubt that your industry has a similar analogy.

Because things are no longer planned, but rather “emerge,” the key is to participate in the communities who are initiating change, and help drive the forward-moving innovation.  Think about the “Big Data” market where tons of companies making small steps forward are creating massive market changes. The same is happening with AI.
Organizing humans is now about creating context for individual action. The new model for industry success is “Try, Learn, & Modify.” Organizations who figure out how to reward fast failure, continually adapt to changing plans, and participate inside their respective market communities at scale will thrive. If you embrace, rather than fear the rapid change in the world, you will have the chance to be apart of it.

DRBD 9 Now Supports Fencing In Pacemaker

Fencing is the process of isolating a node from a computer cluster or protecting shared resources when a node appears to be malfunctioning. As the number of nodes in a cluster increases, so does the likelihood of failure.1

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Albireo Virtual Data Optimizer (VDO) on DRBD

TL;DR: Pairing DRBD with VDO reduces the replication network and storage utilization by ~85% while increasing load by ~0.8.

VDO (Virtual Data Optimizer)[1] is a ready-to-run software package that delivers block-level deduplication, compression, and thin provisioning capabilities to Linux. VDO operates inline at a 4 KB granularity, delivering the best possible balance of performance and data reduction rates.

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DRBD 9 over RDMA with Micron SSDs

We have been testing out some 240GB Micron M500DC SSDs with DRBD 9 and DRBD’s RDMA Transport layer.  Micron, based in Boise Idaho, is a leader in NAND, flash production and storage.  We found that that their M500DC SSD’s are write optimized for data center use cases and in some cases exceeded the expected performance.

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Persistent and Replicated Docker Volumes with DRBD9 and DRBD Manage

Nowadays, Docker has support for plugins; for LINBIT, volume plugins are certainly the most interesting feature. Volume plugins open the way for storing content residing in usual Docker volumes on DRBD backed storage.

In this blog post we show a simple example of using our new Docker volume plugin to create a WordPress powered blog with a MariaDB database, where both the content of the blog and the database is replicated among two cluster nodes. Read more

RDMA Performance with Real Storage

As an update to the previous post, we now have the Tech Guide for RDMA performance with non-volatile storage available online.

Just head over to the LINBIT Tech Guide area and read the HGST Ultrastar SN150 NVMe performance report! (Free registration required.)

Having Fun with the DRBD Manage Control Volume

As you might know, DRBD Manage is a tool that is used in the DRBD9 stack to manage (create, remove, snapshot) DRBD resources in a multi-node DRBD cluster. DRBD Manage stores the cluster information in the so called Control Volume. The control volume is a DRBD9 resource itself which is then replicated across the whole cluster. This means that the control volume itself is just a block device, like all the regular DRBD resources. Read more