This is a “note to self” type post, and basically because Google seems unable to find a direct answer to this simple question.
So it’s simple as this
(config)# interface ethernet NN
(config-if)# no channel-group
et voilà, the ethernet port doesn’t belong anymore to the port channel. It should work with PowerConnect 5324, PowerConnect 5424, PowerConnect 5448, PowerConnect 5548 etc.
We are planning to put online a MySQL NDB Cluster soon (more on this in another post), and one thing you have to do before putting anything in production is to monitor it for problems. In the case of a NDB cluster, you should care about monitoring your limited resources – basically because is a in-memory database – and be alerted when your developers are filling up the dedicated tablespace.
You can do this in two ways: performing a SELECT on the ndbinfo database through the MySQL interface to NDB or parsing the ndb_mgm output. I prefer the latter because maybe I’m using another frontend to the data (native NDB API, memcached etc) and I don’t want to maintain a MySQL server frontend just to check how much space I still have free.
So, you can use this script on GitHub
to parse its output and know if your tablesapce is OK, warning or critical. Feel free to post any comment, fork it and send patches! :)
This is a self-note in the case I encounter another strange behaviour like this. We were experiencing a strange problem with MySQL and DNS. I was trying to do this:
$ mysql -h server.mysql
Unknown MySQL server host 'server.mysql' (-1)
but both dig and a normal ping (which in turns uses libc and nsswitch to do the name resolving) were working:
$ dig +short server.mysql
$ ping server.mysql
PING server.mysql (192.168.10.1) 56(84) bytes of data.
64 bytes from server.mysql (192.168.10.1): icmp_req=1 ttl=64 time=0.399 ms
and obviously connecting using the MySQL client and the IP address worked. So, what was happening? The smarter amongst you maybe already know the problem: a very very large line in /etc/hosts was driving the mysql client crazy (but not ping). Removing the “files” database fron the hosts entry in /etc/nsswitch.conf showed where the problem lied, and fixing the bad-ass line fixed the problem
We have a little internal Hadoop cluster for development and testing, two very powerful Dell PowerEdge R815 with Debian and a bunch of Xen VMs to reproduce a production environment. Problem is that the cluster, even with a relatively small amount of data, was sloooow. And when I say slow I mean almost unusable for Hadoop development (a mapreduce on a small dataset took 5x more than on the big one in production). Even an insignificant
$ hadoop fs -ls
took more than 4s to list the content of HDFS. strace was showing tons of wait() syscalls for no apparent reason, while in the production system the same operation takes 1s and no wait() at all.
After trying almost everything (even without Xen and running Hadoop on the bare metal), I changed by chance a Power Management option in the R815 BIOS. By default it was set to Active Power Controller. Changing it to Maximum Performance did the trick! The ls now takes about a second, just like the production environment. My guess is that probably the default value (which is some kind of automagical load detection) wasn’t able to see that the machine really needed power when running Hadoop, leaving the CPU underclocked to save energy. Maximum power probably is not so green but it solved the problem
Starting from PHP 5.3.9 there is a brand new php.ini option: max_input_vars. You may read in the PHP documentation about it. But what you don’t probably now is that if you are using the Suhoshin patch (for example if you’re using dotdeb packages), then you need to tweak 2 other variables to increase the max number of POST variables accepted by your PHP.
So, if you want to increase this number to, say, 3000 from the default number which is 1000, you have to put in your php.ini these lines:
max_input_vars = 3000
suhosin.post.max_vars = 3000
suhosin.request.max_vars = 3000
The other suitable option is to fix your form and make it saner :)
If you happen to see a message like this
seg fault or similar nasty error detected in the parent process
when reloading Apache2, and if you’re using PHP5 through mod_php5, then it may be related to having an extension loaded via php.ini and not really present on the system. It was my case with a redis extension (redis.so) and I banged my head a day before finding it.
This should apply to Ubuntu Server as well (10.10, 11.04) but it’s tested to work 100% on Debian Squeeze 6.0.
Puppet Dashboard is a neat piece of software really useful if you ara managing a good number of hosts without Puppet.
First of all, install the required deps:
# aptitude install ruby rake dbconfig-common libdbd-mysql-ruby mysql-client rubygems libhttpclient-ruby1.8
you’ll probably have lots of them already installed if you are running Puppet master on the same host (which by the way is not mandatory).
Then, download and install the deb package:
# wget http://downloads.puppetlabs.com/dashboard/puppet-dashboard_1.2.0-1_all.deb
# dpkg -i puppet-dashboard_1.2.0-1_all.deb
Enable the daemon editing the default file /etc/default/puppet-dashboard and then customize your database definition by editing /etc/puppet-dashboard/database.yml which should looks something like this:
if you plan to use MySQL as a backend. Remember to create the database and grant the appropriate privileges to the user
GRANT ALL PRIVILEGES ON puppet_dashboard.* TO 'puppet_dashboard'@'%' IDENTIFIED BY 'secret_password';
Now we have to populate the database, Rails way
# cd /usr/share/puppet-dashboard/
# rake RAILS_ENV=production db:migrate
Now you can start /etc/init.d/puppet-dashboard and /etc/init.d/puppet-dashboard-workers and you should be already able to access http://your-host.yourdomain.tld:3000 and see the Puppet Dashboard.
You just have to do two thing more before you can see any actual data in it: enable report sending in the Puppet clients and tell Puppet Master to pull those reports to the Dashboard via HTTP.
So, edit /etc/puppet.pupept.conf on the clients (I suggest you to do it via puppet if you do not already have this setting in it) and add
# ... whatever you already have
and on the Master side
# ... whatever you already have
reports = store, http
reporturl = http://your-host.yourdomain.tld:3000/reports/upload