Category Archives: Blog

Blog posts by Nick

apc.php for rhel / centos

Note to self: The apc.php (script for monitroing apc performance) is stored in – /usr/share/doc/php-pecl-apc-3.1.3p1

rxalarm – Alarm Console (webhook) for Rackspace Cloud Monitoring.

When rackspace launched cloud monitoring I was really interested, especially since leaving AWS… I kind of felt a bit blind to what my servers were doing.

By default, the monitoring service sends you emails for up/down alarms… just what we need more emails! … So I have started to write an alarm console which is a compatible webhook for their API…. i.e. you can send alarms to it!

My Webhook is called [rx]Alarm… rx as in receive :)

The source code is on github (rxalam repo) and a working copy is on openshift (rxalam site).

This may end up being yet-another-project-I-don’t-finish … or it maybe not, only time will tell!

php basic twitter oauth example

Oauth it seems tricky, to help me understand I’ve attempted to code up an example which allows users to log into a php app with their twitter credentials.

The code has been pushed to a branch of my abandonware repo as I don’t plan to make on any future changes, checkout README.md for some info on how the code works.

https://github.com/linickx/a/tree/oauth

I found it quite difficult to find some simple code to do this, so hopefully ^that^ will help someone else :)

Speed, I am Speed

Recently I’ve been focusing on getting linickx.com not only available, but snappy too!

  1. HA Proxy distributes the load across two cloud servers
  2. Varnish Caches have a hit rate of between 30% & 49%
  3. WP Super Cache serves up static files to Varnish
  4. HypderDB distributes MySQL Requests across my two servers

My next step is to get some minification going, either with page-speed or a WP-Plugin.. they seem to be a bit tricky to troubleshoot tho!

If you are looking to measure your websites performance, I’ve been using pingdom for server response times and webpagetest.org for gathering client load speeds.

OCFS2 issues

This morning I’ve had issues with my linickx.com cluster, the file system on both nodes went to read-only and I ended up in a world of pain.

[root@georgia ~]# sudo /etc/init.d/httpd start
Starting httpd:
[root@georgia ~]# tail -f /var/log/messages
Jan  9 09:48:35 georgia kernel: [  474.259265] (httpd,1712,0):ocfs2_reserve_clusters_with_limit:1190 ERROR: status = -22
Jan  9 09:48:35 georgia kernel: [  474.259271] (httpd,1712,0):ocfs2_lock_allocators:2546 ERROR: status = -22
Jan  9 09:48:35 georgia kernel: [  474.259276] (httpd,1712,0):ocfs2_write_begin_nolock:1732 ERROR: status = -22
Jan  9 09:48:35 georgia kernel: [  474.259282] (httpd,1712,0):ocfs2_write_begin:1856 ERROR: status = -22
Jan  9 09:49:31 georgia kernel: [  530.660071] o2net: no longer connected to node amy (num 1) at 10.176.128.7:7777
Jan  9 09:49:31 georgia kernel: [  530.661856] ocfs2: Unmounting device (147,0) on (node 2)
Jan  9 09:59:46 georgia kernel: [ 1145.772174] o2dlm: Nodes in domain E9447DBE28154DAEA1B988CEC573EB64: 2
Jan  9 10:01:05 georgia kernel: [ 1223.911192] o2net: connected to node amy (num 1) at 10.176.128.7:7777
Jan  9 10:01:09 georgia kernel: [ 1227.933348] o2dlm: Nodes in domain E9447DBE28154DAEA1B988CEC573EB64: 1 2
Jan  9 10:01:09 georgia kernel: [ 1227.938693] ocfs2: Mounting device (147,0) on (node 2, slot 1) with ordered data mode.
Jan  9 10:02:35 georgia kernel: [ 1314.467741] OCFS2: ERROR (device drbd0): ocfs2_validate_gd_self: Group descriptor #419328 has bit count 32256 but claims that 45941 are free
Jan  9 10:02:35 georgia kernel: [ 1314.467754] File system is now read-only due to the potential of on-disk corruption. Please run fsck.ocfs2 once the file system is unmounted.
Jan  9 10:02:35 georgia kernel: [ 1314.467764] (httpd,2389,0):ocfs2_search_chain:1729 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467771] (httpd,2389,0):ocfs2_claim_suballoc_bits:1902 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467778] (httpd,2389,0):__ocfs2_claim_clusters:2185 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467783] (httpd,2389,0):ocfs2_local_alloc_new_window:1204 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467790] (httpd,2389,0):ocfs2_local_alloc_slide_window:1306 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467798] (httpd,2389,0):ocfs2_reserve_local_alloc_bits:695 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467803] (httpd,2389,0):ocfs2_reserve_clusters_with_limit:1190 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467809] (httpd,2389,0):ocfs2_lock_allocators:2546 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467814] (httpd,2389,0):ocfs2_write_begin_nolock:1732 ERROR: status = -22
Jan  9 10:02:35 georgia kernel: [ 1314.467821] (httpd,2389,0):ocfs2_write_begin:1856 ERROR: status = -22
Jan  9 10:02:36 georgia kernel: [ 1315.046965] OCFS2: ERROR (device drbd0): ocfs2_validate_gd_self: Group descriptor #419328 has bit count 32256 but claims that 45941 are free
^C
[root@georgia ~]#

What made this odd is that running fsck.ocfs2 as suggested made no difference, as the output said that the disk was clean.

[root@georgia ~]# fsck.ocfs2 /dev/drbd0
fsck.ocfs2 1.4.4
Checking OCFS2 filesystem in /dev/drbd0:
  Label:              linickxcluster
  UUID:               E9447DBE28154DAEA1B988CEC573EB64
  Number of blocks:   1048535
  Block size:         4096
  Number of clusters: 1048535
  Cluster size:       4096
  Number of slots:    4

/dev/drbd0 is clean.  It will be checked after 20 additional mounts.
[root@georgia ~]#

I learn that in fact the above output was a lie! For any future googlers seeing the same issue, run:

fsck.ocfs2 -fy /dev/drbd0

The f & y force a check and fix any found issues, the force on my filesystem found the errors and we appear to be back online :)

NYr2012

I’m not big on New Year’s Resolutions but this year I can feel a couple brewing.

Better Communication
I’m going to move to text only email, not because I’m an advocate… actually the opposite, I think RTF/HTML email can bring clarity to text… anyway … reason being I think that my communication could be improved. If I remove the luxury of bold/italic/etc then my text has to stand alone for what it is, hopefully this will lead to better text.

Social Networks
I fall in and out of love with my twitter & facebook account but FB’s move to disable the auto-magic import of linickx.com posts has forced me to think about this. My basic requirement is that, LINICKX.com is my source of noise and I need an elegant way to broadcast :)

Happy New yr to All!