When we completely fill up an ext4 filesystem mounted on a partition hosted in an EBS volume of Amazon Web Services and we can not do anything to free space because we do not want to lose any of the stored data, the only solution is to grow up the volume and extend the associated partition up to 100% of its capacity to obtain free space again.
DanielHow to enlarge the size of an EBS volume in AWS and extend an ext4 partition
Through the following instructions you can easily get a permanent access_token to automatically connect your applications to a Facebook page and be able to obtain for example your number of followers periodically, get new likes or comments in real time, publish new entries in the timeline, or any of the possibilities offered by the Facebook Pages API.
DanielHow to get a permanent token to access a Facebook page
This was a very interesting project related to the automotive business in which I led a technical team of 4 people in the design and development of a complete software intended for conducting live car auctions both onsite and online in a large industrial building especially conditioned for this kind of events. Unfortunately, despite the beauty of the project and being a startup with great potential and highly talented team of almost 20 people, the application could not finally be used in a real scenario because the company wound up before it could actually start due to various commercial and management issues.
However, at the technical level the application was implemented and deployed completely, fulfilling very satisfactorily the requirements and objectives initially set out. Our application was mainly inspired by the BCA and Autorola car auction softwares, and also others like CarsOnTheWeb, Manheim, EurocarBid, Subastacar, Subasto mi Coche, etc. I humbly believe that we managed to improve them in several ways.
DanielWeb application for live onsite and online car auctions
The CPU average load value is a very important metric to understand the behavior of a Linux system, and especially its current and recent past status. Many times there is confusion between this term and percentage of CPU usage, but differences are important. In this article I will try to explain the true meaning of both and how to tell if a Linux box is overloaded or underutilized.
DanielWhat is the true meaning of system average load and CPU utilization in Linux?
I am a strong supporter of simplicity and the principle that less is more, but as far as security and performance of information systems is concerned, we must be able to strike a balance between keeping things simple and exposing ourselves as little as possible to potential threats while trying to obtain the maximum performance of all system elements involved.
It is a common practice that the various distributions of Linux, and even the images used to launch Linux virtual server instances as in the case of AWS AMI’s, implement by default an extremely simple partitioning scheme consisting in a single partition that covers the entire disk. It is in this only partition where the root filesystem (/) is mounted and in which all the directories that configure the file hierarchy of a Linux operating system are placed.
But one of the features of Linux is precisely that it allows you to be highly flexible in placing each of these directories on different partitions or on different disks if necessary.
DanielThe importance of properly partitioning a disk in Linux
When we try to know a computer’s architecture and performance at CPU level using Linux commands like nproc or lscpu, we often find out that we are not able to properly interpret their results because we confuse terms such as physical CPU, logical CPU, virtual CPU, core, thread, socket, etc. If we add concepts like HyperThreading (not to be confused with multithreading), we are in a situation where we can not be sure how many cores our box has, we don’t understand why commands like htop indicate that we have 8 cpus when we thought we had bought a single quad-core processor, etc. In short, it’s a mess.
DanielDifferences between physical CPU vs logical CPU vs Core vs Thread vs Socket
One of the most common and tedious tasks of a sysadmin is to prevent file systems become completely full, because when a server runs out of space the consequences are unpredictable. Depending on how you structured the root file system and if it is divided into different partitions or volumes, those consequences will be more or less severe, but in any case undesirable.
Daniel15 most useful Linux commands for file system maintenance
Less than two days after it was detected a vulnerability (CVE-2014-6271) that affects the Bash shell on Linux, Unix and Mac OS X, a patch was released that solves this issue only partially, which forced to report a new vulnerability (CVE-2014-7169) still pending. This issue has quickly gained a simple name by which it will be remembered for a long time: Shellshock or Shell Shock.
DanielStill unresolved Shellshock major vulnerability affecting Bash on Linux, Unix and MAC OS X