[cs615asa] HW#N: Attend a relevant Meetup/Talk/community event

[Peixuan Ding]

Hi guys,

For Homework#N, I attended the monthly user group meeting of Red Hat in April. The information about the meetup can be found here: www.meetup.com/NYRHUG-New-York-Red-Hat-Users-Group/events/230144680/.

Red Hat is the world’s leading provider of open source products. The most well-known product of Red Hat is its operating system RHEL(Red Hat Enterprise Linux). RHEL also has a community version named CentOS, which is basically Red Hat without the technical support from Red Hat.

The reason I choose this meetup is that it’s mainly about the container technology. Container technologies, especially Docker, is getting more and more popular nowadays. A lot of companies choose to use containers make the software deployment process easier. Also, containers are based on some basic OS knowledge that a system administrator must know, so it’s very important for us to know about the basic ideas behind containers.

In this meetup there are two talks, one is RHEL 7 memory management changes, a quick talk by Mr. Andrea Arcangeli, who has been working for Red Hat as a kernel developer for 16 years. Another talk is Container Technology by Mr. Patrick Ladd, a technical account manager from Red Hat.

In the first talk, Andrea Arcangeli gives the memory management changes in the recently released RHEL 7. The most significant change is the a new technology called Automatic NUMA Balancing. NUMA(Non-uniform memory access) is a memory management design used in multiprocessing. In multiprocessing, the memory access time depends on the memory location related to the processor. By using NUMA, a processor can access its own local memory faster than non-local memory. In RHEL 7, the autocatic NUMA balancing feature improves the performance of applications running on NUMA hardware systems. Automatic NUMA balancing simply moves processes closer to the memory they are accessing and moves application data to the memory location closer to the processes that using it. Automatic NUMA balancing comes out of box with the RHEL 7 release and is handled & enabled automatically by the kernel. However, it is important for sysadmins to know how to control it in some scenarios. Andrea gave us a demo about how to enable & disable NUMA and showed us some memory benchmark results with & without automatic NUMA balancing.

I didn’t know anything about NUMA before attending the meetup, and this presentation really helps me a lot to know the idea of memory optimization in multiprocessing.

The second talk is about the container technology by Patrick Ladd. The talk is mainly about the basic ideas behind containers. Container technology mainly consists of 3 major concepts: namespace, network interface, and overlay filesystem.  

In the namespace part, we mainly talked about PID namespace. Container technology uses different PID namespace to isolate host processes and container processes. Processes in a container are in the namespace provided by the container itself and can only see the processes in the same namespace, which ensures that processes in containers can be isolated from the host OS.
The second part is about network isolation. To implement network isolation, the container technology uses a virtual network interface, which has a private IP address. For example, if we run a MySQL server in a container, the MySQL server listens to the TCP port 3306 of its virtual network and is isolated from the host network. We can also map a port from a container to the host’s network. In the previous example, we can map the TCP port 3306 from the MySQL container to the same port of the host OS, then other outside services can access to the MySQL server through the mapped port.
The third part is about the union file system, which allows multiple file systems to be transparently overlaid into a single file system so that each container can have its own isolated filesystem.
In the end of this talk, Patrick gave us a demo of some basic operations on a Docker container.

In this meet up, I consolidated my OS knowledge and learned the basic idea behind the container technology. It’s totally worth the time and I would definitely love to attend their next monthly meet up.

Best,

Peixuan Ding

Peixuan Ding
Stevens Institute of Technology
Email	pding2 at stevens.edu
Telephone	+1 201 208 9980
        

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