SYSbible

A bible next to an old computer.

  • VMware Virtual Disk Manager examples

    Converting growable into preallocated disk This line will convert the growable virtual disk ‘WebFileServer.vmdk’ to type 3 (aka ‘preallocated virtual disk split in 2Gb files’). The resulting virtual disk will be created as ‘WebFileServer_pre-alloc.vmdk’. See Also Manipulating VMWare Virtual Disks with Virtual Disk Manager VMware Virtual Disk Manager usage

  • Using ejabberd with MySQL native driver

    Get mysql driver (if ejabberd < 2.0.0) If you are using an ejabberd version previous to 2.0.0 (about end of 2007) then you need to put the MySQL .beam files somewhere in your Erlang path (possibly with your ejabberd .beam files): Mysql initialization Empty database creation: Schema creation: Check that the database structure has been […]

  • Sticky sessions (aka persistence)

    While working with load balancers it is sometimes required that the client connects to the same backend server all the time. This concept has several names (e.g.: sticky sessions, session stickiness, persistent sessions, persistence, etc…). Wikipedia explains this concept clearly: One dilemma when operating a load-balanced service, is what to do if the backend servers […]

  • Opening Large Capture Files with WireShark (aka Ethereal)

    Sometimes it might be needed to open ”’big”’ network traffic capture files (a.k.a. .cap) . This challenge is commonly encountered since this sort of logging it is usually very verbose. Leaving a packet sniffer (such as tcpdump) overnight logging all the packets that go through a network interface card might generate several gigs of data. […]

  • Showing MySQL Permissions

    Usage: Example: See Also Granting MySQL Permissions Show Permission MySQL Commands

  • Manipulating VMWare Virtual Disks with Virtual Disk Manager

    From Using VMware Virtual Disk Manager: VMware Virtual Disk Manager is a utility in VMware Server that lets you create, manage, and modify virtual disk files from the command line or within scripts. One key feature is the ability to enlarge a virtual disk so its maximum capacity is larger than it was when you […]

  • HAProxy hot-reconfiguration

    As of version 1.2.8, a new soft-reconfiguration mechanism has been introduced. It is now possible to “pause” all the proxies by sending a SIGTTOU signal to the processes. This will disable the listening socket without breaking existing connections. After that, sending a SIGTTIN signal to those processes enables the listening sockets again. This is very […]

  • Fixing VMWare vmxnet driver networking issues under Debian Linux

    It seems that using particular combinations of VMWare Server and Linux Kernel version(s) while installing VMWare Tools under Linux guest machines, may render the virtual machine’s networking down. This page provides a “hacky” workaround to solve this situation. There might be other deeper and more proper solutions out there but I came up with this […]

  • HAProxy 1.3.15.2 installation under Debian Etch (compiling from sources)

    HAProxy is an excellent load balancer which performs extremely well. This page explains how to install HAProxy 1.3.15.2 since this is one of the recommended versions on the ”HAProxy Mailing List”: Server response time discrepancy Also, it has been recommended on that thread to use one of the following kernels: 2.6.22 2.6.25 2.6.18 Installation Steps […]

  • Granting MySQL Permissions

    Usage Examples Notes WITH GRANT OPTION should only be added when really needed; this privilege allows a user to grant to others (more info). The location from where a user can connect (i.e. ‘username’@’server’) can be also a network if specified as  ‘username’@’10.120.%.%’ See Also Showing MySQL Permissions GRANT Syntax