Month: September 2012

Nagios Plugin for Checking Backups via rsnapshot

We’ve just added a check_rsnapshot.php script to our nagios-plugins bundle on Github. This script will verify rsnapshot backups via Nagios using a number of checks / tests:

  • minfiles – checks the number of files in a snapshot against a minimum expected number;
  • minsize – checks the size of a snapshot against a minimum expected size;
  • log – parses the rsnapshot log to ensure the most recent runs for each retention period completed successfully;
  • timestamp – checks for files created server side containing a timestamp and thus ensuring snapshots are succeeding;
  • rotation – checks that retention directories are being rotated; and
  • dir-creation – checks that retention directories are being created.

Please see this Github wiki page for more information including instructions.

Analysing MySQL Slow Query Logs

MySQL has a really useful feature that allows it to log slow queries where slow is a minimum time defined by you in micro seconds. It helps a lot is diagnosing website outages or slow responsiveness issues after the fact.

Unfortunately I couldn’t find any nice graphical tools for analysing these but there are a few command line tools:

mysqldumpslow

MySQL’s own tool, mysqldumpslow, which aggregates queries and allows you to sort them by: query time or average query time; lock time or average lock time; rows sent or average rows sent; or the number of queries.

Percona’s MySQL Slow Query Log Analyser

Dating from 2006, Percona’s Peter Zaitsev wrote about their own version of a slow query log analyser (local copy) which has given me good results. Note that their micro time patch has since been incorporated into MySQL mainstream.

One of the main differences over MySQL’s own version is that as well as printing the aggregated query (with number and string literals wildcarded), it also prints a real example of the query allowing a copy and paste to MySQL for execution with EXPLAIN.

Example output with query details redacted:

### 230 Queries 
### Total time: 4708.948293, Average time: 20.4736882304348
### Taking 0.093420 to 203.693466 seconds to complete
### Rows analyzed 0 - 141008
SET timestamp=XXX;
SELECT ... FROM ... AS A 
        INNER JOIN ... AS C ON C.item_id = A.item_id 
    WHERE XXX AND C.item_lang = 'XXX' AND ... 
    ORDER BY CATALOG.item_sort LIMIT XXX;

SET timestamp=1348032761;
SELECT ... FROM ... AS A 
        INNER JOIN ... AS C ON C.item_id = A.item_id 
    WHERE 1 AND C.item_lang = '1' AND ... 
    ORDER BY C.item_sort LIMIT 1;

 

So it’s finally happened…

RIPE put out a press release today:

RIPE NCC Begins to Allocate IPv4 Address Space From the Last /8

14 Sep 2012

On Friday 14 September, 2012, the RIPE NCC, the Regional Internet Registry (RIR) for Europe, the Middle East and parts of Central Asia, distributed the last blocks of IPv4 address space from the available pool.

This means that we are now distributing IPv4 address space to Local Internet Registries (LIRs) from the last /8 according tosection 5.6 of “IPv4 Address Allocation and Assignment Policies for the RIPE NCC Service Region“.

This section states that an LIR may receive one /22 allocation (1,024 IPv4 addresses), even if they can justify a larger allocation. This /22 allocation will only be made to LIRs if they have already received an IPv6 allocation from an upstream LIR or the RIPE NCC. No new IPv4 Provider Independent (PI) space will be assigned.

It is now imperative that all stakeholders deploy IPv6 on their networks to ensure the continuity of their online operations and the future growth of the Internet.

In other words, for all intents and purposes, Europe (and Central Asia and the Middle East) is out of IPv4 addresses. Funnily enough, I’m actually happy that this long predicted day has arrived and we can start the next phase of IPv6 deployment.

Thunderbird 15 Released with Chat – But Shite Error Handling

I’ve just moved a couple of my chat and IRC accounts over to Thunderbird 15 to see how they look. After all, one communications application is better than three. Mozilla have a good instruction set here and they work well for standard chat accounts.

However, most corporations using in house XMPP servers with self signed certificates and these fail with no error messages whatsoever. It was by fluke I found this post: How to Make Thunderbird Chat Work with Most XMPP/Jabber Accounts. Thanks for doing the legwork Rod, this helped a lot.