RHCE Certification

I got my results for both RHCSA and RHCE exams: pass! I've done the RH300 training earlier this months and it was a great experience.

Comments

Post a Comment

Popular posts from this blog

Networker automated recovery testing using the REST API - introduction

One feature that is lacking from Networker, compared to some of its competitors, is the built-in automatic recovery testing. However, when there's an API, there is a way.  Networker's REST API is not perfect, but it allows the backup administrator to perform queries about Networker resources (objects). As my workload is going up, I realize that one of the tasks that I tend to skip the most is the periodical recovery tests.  Don't forget that a a backup that is not tested should be considered non-successful. I also found out that my recovery tests were not diverse enough. When I started this project, I knew a little bit about REST APIs, and nothing about JSON processing. With the Networker REST API documentation, and the help of a friend and Networker Support staff, I was able to create HTTP queries with Postman,  cURL and jq . Once I got the queries that I needed, I put them in a bash script that would somehow select one backup, and then restore it. My first attem...
Read more

General linux performance troubleshooting

Here's a list of commands that you should execute and then share the output to someone who can help you figure out what resource is the bottleneck in your system. Note, it requires the  sysstat  and  procps  packages (ubuntu and RHEL and its derivatives): uptime vmstat 1 10 iostat -xN 2 10 mpstat -P ALL 3 10 pidstat 1 10 free -mw (or free -m, if your OS doesn't support -w)  uptime is to see the load averages on the system. vmstat is mostly used to tell if the system is swapping or not. If you see significant numbers in the 'si' and 'so' columns, your system is most likely swapping (using the hard drive as RAM), which usually slows performance a lot. iostat is mostly used to determine if your disk subsystem is not able to cope with the load. If you see one or more lines that shows 100 or close almost constantly, it is probably the case.  If it is your swap volume, you probably saw numbers in the 'si' and 'so' columns in the  vmsta...
Read more

Symfony - clear cache

I was a bit surprised when I learnt that the only way to clear the cache on a Symfony 4 system is to run a local command on the system, as I don't want anyone to log into a production server (deployment is automated). And when you run the command, you must run it as the user that your web server is running under.  For distros of the Red Hat family, this user is apache by default.  For the Debian family, it is www-data. Here is how I did it.  Let's say that the user that is used for automated deployment is 'user123', here's what I did: Create a file in the /etc/sudoers.d directory (example: /etc/sudoers.d/user123_bin_console) Put this line in the file: user123 ALL=(apache) NOPASSWD: /path/to/bin/console Once this file is in place, you can log into the system and execute the sudo -l command to show what commands this user is allowed to execute via sudo and make sure the command you specified in the newly created file is present To clear the cache, execute this command...
Read more