Every true sysadmin has been in this predicament — “I need to run this command on a bunch of machines.” The typical approach is to create a for loop, and run the command serially. This works well, but if a) you have tons of hosts, or b) the command takes […]

Run multiple ssh commands in parallel with GNU Parallel

If a replica shard is in an INITIALIZATION state and the primary shard is healthy, then the shard is being replicated from the primary to the replica. You can use the cat API to get this state: [crayon-5a17fae61cf23436846479/] Now, we have no clue from this view what progress has been […]

Elasticsearch cluster administration notes

Promox has built-in support for installing templates, but they’re pretty outdated and not well-maintained.  openvz.org, on the other hand, regularly updates their templates, and has a wide selection to choose from. In order to make these templates available for use in Proxmox, it’s simple.  Get the links for the templates […]

Installing OpenVZ templates in Proxmox

The Cyrus IMAP server (which is used by FastMail, FYI), is pretty picky when it comes to enforcing RFCs.  When performing a recent email migration (from Zoho, which is less picky), I got a boatload of errors along the way. With each of my messages as individual files (downloaded as […]

IMAP Append – Message contains bare newlines

There are times when I need to create a number of OpenVZ containers in Proxmox at once, which would take way too long via the user interface.  There are a number of ways to accomplish this programmatically, but the most straightforward (assuming you have root access) is via [crayon-5a17fae61d984096921242-i/] . Below is […]

Create multiple Proxmox containers via script

  [crayon-5a17fae61e1aa943715332/] You’ll now need to have this module loaded in PHP; this varies depending on which handler you use: [crayon-5a17fae61e1b2613014948/] cd into wp-content/plugins [crayon-5a17fae61e1b7756518809/] In wp-config.php: [crayon-5a17fae61e1bb839209199/] In your admin dashboard, enable “WP XHProf Profiler” from the plugins section. You will have “Profiler output” links at the very bottom […]

Enable XHProf for WordPress

It happens — you’re on a server that just can’t be upgraded any further, and you need more resources.  Or, you need to backup a Chef server.  Or, you need to setup a QA instance.  Or, you need to finally migrate from Chef 10 to Chef 11.  Or, you have […]

Migrating from one Chef server to another

Just about every significant aspect of Chef Server is configurable, although the defaults are okay for most.  The configuration options are documented at http://docs.opscode.com/config_rb_chef_server_optional_settings.html . Note, though, that the chef-server.rb described in the article was nowhere to be found on my server.  Instead, after some digging, I found what I needed at [crayon-5a17fae61f0ad504807445-i/] . […]

Change Chef Server settings after installation

Everyone loves speed.  That includes your site’s visitors.  If you run a WordPress site, WP Super Cache is a pretty cool plugin that generates static files from your dynamic content, and serves those to your users instead of dynamically generating the same page for each user, which can really put your database […]

Use nginx as a reverse proxy to speed up your ...