Universal Serial Bus, more commonly known as the USB has been around for quite some time now with almost every device following the standard. From our I/O devices to storage drives and even mobile phones can be connected using the USB standard. USB ports version will be explained below
This standard has evolved over the years from its inception in the mid 90’s and has had multiple versions through its history.
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Disks getting full on Linux is a common scenario any administrator have probably experienced. There are usually some large files in /var/log directory that can be compressed or deleted to save disk space. Have you ever experienced deleting a large log file and noticed that the disk usage remained the same ? It’s as if the file size usage is not released even though you’ve deleted it?
This scenario can happen if you deleted/renamed/moved an existing file that is currently in use by a running program. This usually happens on log files that are not rotated regularly and then when the file size becomes large, you deleted (or compressed) the file without even checking if it is in-use. Don’t worry, you can still recover your disk space as shown from the example below.
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If you are installing an application on HP-UX (usually Database programs) and it requires specific kernel parameters, you can make adjustments using the kctune command. Here’s an example of changing kernel parameters on HP-UX.
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In HP-UX if you need to adjust an existing LVM Volume Group Max Size to accommodate a new physical disk, here is an example which use the vgmodify command.
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Load balancers are used to distribute the requests/queries to multiple server instances. Most web infrastructures have multiple front-end servers that share the load of the application. Although there are multiple server instances, the end-user only see them a single node. In this tutorial, I’ll walk you on how to configure an Elastic Load Balancer on Amazon, add your web server nodes and point your domain name to the EC2 load balancer.
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Multiple front-end web server setups are almost always in use these days. Instead of just one server serving web traffic, you create two or more servers which will share the load evenly to serve requests from users. These servers usually connect to a backend database server. On this tutorial, we’ll walk through the steps on adding another web-front end server by cloning you current web server node.
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Amazon VPS instances, by default only have a single disk for the whole filesystem of the server. Unless you chose to add an additional disk when you provision the server, adding disk space to your VPS can be tricky. Here’s a run down on how to add more storage to your server on amazon by mounting a new drive.
In this tutorial, I’ve mounted the new drive to /var/lib/mysql since I need to increase the disk space used by the database. This tutorial is still applicable even if you want to increase a different folder. The process will be the same.
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Unison is a file-synchronization tool similar to rsync. The main difference is that unison tracks changes on both directions so you don’t to have two separate rsync to pull and push data on both folders. This means files changed on server1 will be replicated to server2 and vice versa. It’s also easier to setup since no scripting necessary.
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