Archivio tag: troubleshooting

Bookmarks for 15 mag 2015 through 17 mag 2015

These are my links for 15 mag 2015 through 17 mag 2015:

Bookmarks for 2 ott 2014 through 3 ott 2014

These are my links for 2 ott 2014 through 3 ott 2014:

Bookmarks for 25 set 2014 from 12:03 to 17:40

These are my links for 25 set 2014 from 12:03 to 17:40:

  • sebsauvage/rss-bridge – The RSS feed for websites missing it
  • debsecan – The debsecan program evaluates the security status of a host running the Debian operation system. It reports missing security updates and known vulnerabilities in the programs which are installed on the host. debsecan accesses the dpkg database and obtains a list of installed packages and their versions. This list is then evaluated against a feed of vulnerability information which ultimately comes from a database maintained by Debian's Testing Security Team . Various output formats are supported, including incremental reporting via email. Beginning with version 0.2, debsecan includes a script called debsecan-create-cron, which allows you to create a cron job which periodically sends you mail (once per day) when the security status of the system changes.
  • Barriers, Caches, Filesystems | monolight – With the recent proliferation of ext4 as the new “default” Linux filesystem there’s been much talk of write barrier support. The flurry of post-2.6.18 barrier related development in most storage subsystems has left some novice users and administrators perplexed. I hope I can clear it up a bit with this primer/refresher.
  • SMTP, testing via Telnet – FreeBSDwiki – When troubleshooting problems with SMTP service – your own, or others – it is frequently very helpful to be able to "speak" to the SMTP server directly, rather than going through a mail client which won't necessarily tell you exactly what the SMTP server is saying. You can easily do this with the telnet client. Note that many ISPs do not allow outbound connections on port 25 to any SMTP server but their own – if you get timeouts when trying to connect to port 25, you should try port 587, which is the standard ESMTP port. (Port 587 connections normally require SMTP AUTH, which is covered below.)

Bookmarks for 26 ago 2014 through 27 ago 2014

These are my links for 26 ago 2014 through 27 ago 2014:

  • Regular Expressions – Regular expressions ("regexes") are supercharged Find/Replace string operations. Regular expressions are used when editing text in a text editor, to: check whether the text contains a certain pattern find those pattern matches, if there are any pull information (i.e. substrings) out of the text make modifications to the text. As well as text editors, almost every high-level programming language includes support for regular expressions. In this context "the text" is just a string variable, but the operations available are the same. Some programming languages (Perl, JavaScript) even provide dedicated syntax for regular expression operations.
  • MySQL active-passive cluster | Your IT goes Linux – We will use the iSCSI Lun defined in our iSCSI cluster as a shared storage and we will run MySQL in active-passive (fail-over) mode using Pacemaker and Corosync cluster engine. The cluster will have to connect to the iSCSI target, mount the iSCSI partition on one node and start a MySQL service which has all its data on this partition.
  • Perl – […] Perl has horrors, but it also has some great redeeming features. In this respect it is like every other programming language ever created. This document is intended to be informative, not evangelical. It is aimed at people who, like me: dislike the official Perl documentation at for being intensely technical and giving far too much space to very unusual edge cases learn new programming languages most quickly by "axiom and example" wish Larry Wall would get to the point already know how to program in general terms don't care about Perl beyond what's necessary to get the job done. This document is intended to be as short as possible, but no shorter[…]
  • Linux Performance – This page links to various Linux performance material I've created, including the tools maps on the right, which show: Linux observability tools, Linux benchmarking tools, Linux tuning tools, and Linux observability sar. For more diagrams, see my slide decks below.
  • AIXchange: Useful Storage Links – Here's an assortment of really good storage-related articles — the majority of which are found on IBM developerWorks — that are worth your time. While some of them are a few years old, they still provide relevant information.