Sometimes (especially when system works on heavy load) Linux buffers and caches contains a lot of objects. This behaviour is generally highly desirable but let’s take a look at following scenario.
Web server is a victim of a DDoS attack. Most of free RAM is used by caches. DDoS has ended and we quickly need to free some RAM for our main application and database system. Cache will warm-up again but it take some time. We need to initiate cache warm-up now! Continue Reading
Default CentOS repositories contain only most popular packages and doesn’t offer useful packages that are available in other Linux distributions. EPEL repository is an Extra Packages for Enterprise Linux. It provides rebuild of Enterprise Linux packages of Fedora for EL6 and EL7. Generally using that repository is safe and significantly improves system functionality. How to install it? Continue Reading
DU command doesn’t take into account hidden files and directories. For example if you want check disk usage of all files and directories in current directory you can use the following command:
$ du -sm *
Unfortunately this command doesn’t show hidden files and directories. Continue Reading
Varnish is extremely fast and configurable reverse proxy server so it’s very popular. This examples shows how common task can be done using varnishadm command.
How to flush whole varnish’s cache?
# varnishadm ban "req.url ~ ."