HA-OSCAR: the Birth of Highly Available OSCAR
One important factor to consider is the time it takes to build, boot and have the cluster ready to service requests. This is not a major issue for small clusters, but as we move to large installations of 256 nodes and higher, having the capabilities of installing and booting all cluster nodes in an automated and timely manner becomes an asset. HA-OSCAR is considering implementing hierarchical clustering by dividing the cluster into multiple zones. This type of experimentation also can be helpful in identifying the slow processes in the system installation procedure, which allows us to bring it up to speed. LinuxBIOS, for instance, can be included in place of the normal BIOS—with a little bit of hardware initialization and a compressed Linux kernel that can be booted from a cold start—to achieve faster startup times. The upcoming OSCAR release uses multicast technology, which was tested on about 500 nodes, to speed up install times and return impressive numbers. HA-OSCAR plans to adopt this method as the base install mechanism and improve on it.
Similar to the base OSCAR installation, users of HA-OSCAR have the freedom of deciding which application packages to install. By default, HA-OSCAR automatically installs the essential parts to build a cluster and then prompts the user to select the applications they want.
The installation procedure takes into consideration any existing configuration and the packages already installed on the node. Some packages are sensitive to certain system libraries, such as glibc. Users should be aware that installing HA-OSCAR may require them to upgrade their systems based on such dependencies. In the same manner, a de-installation procedure is provided to clean up every HA-OSCAR-specific addition without disturbing the system integrity. This option is important for users who want to test only HA-OSCAR.
It is also worth mentioning that package install and uninstall options are available in the base OSCAR release since v2.0, and a newly enhanced version is coming out soon.
HA-OSCAR plans to investigate the possibility of providing mechanisms for selective network software upgrades without bringing down the system. Network upgrades are an interesting way of patching an operating system and its applications. As an example, most Linux distributions now come with an automatic network upgrade that eases this tedious administrative task. In the case of administrating a large cluster, HA-OSCAR users can use such a feature to upgrade their application version seamlessly, without service interruption. Network upgrade simplifies cluster administration and promotes better software management across all computing nodes.
In addition, HA-OSCAR provides a tool that allows users to change the configuration of the cluster at runtime by using a tool somewhat similar to LinuxConf. This is still a basic idea that will be investigated further in the near future.
Generally, one cannot trust a computing system if there is no backup or recovery mechanism. For mission-critical applications, including telecom applications, it is important to be able to recover from any software or hardware failure. Thus, providing efficient backup and recovery mechanisms is an essential part of any HA system.
In case a disaster occurs, recovery ability and speed are critical. Every time HA-OSCAR is completely re-installed or the kernel updated, ghost images of before and after are saved in a designated location on a backup server and tape. Ghost for Unix takes a snapshot of an old and new kernel, gzips it and sends the image to the secondary head node as well as to a predefined disaster recovery site. Important data as well as application and configuration files also can be included in the ghost image. Normally, tape backup schedules include nightly snapshots for incremental images and weekly snapshots for full images. For faster recovery and highly reliable backups, ghost imaging, file journaling and data replication are implemented.
One goal of HA-OSCAR is to be deployed optionally as a Web server cluster providing highly available Web services to a large number of clients. One step toward this goal is to set up a Web server, such as Apache, on every node; Apache can be one of the packages copied to the nodes. Then, a single IP interface is provided for the cluster, possibly using LVS Direct Routing, because it has proven to be the scalable implementation.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Tech Tip: Really Simple HTTP Server with Python
- Doing for User Space What We Did for Kernel Space
- Rogue Wave Software's Zend Server
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide