So, if anyone is interested in this very simple plugin, here it is. Of course, it’s GPL. I expect I’ll be adding more features to it as I need, but for now this does exactly what I want with very little code to maintain.

Documentation

Download

You can get the current version from here: simplerssembed.zip

Installation

Put the contents of simpleressembed.zip into your wp-contents/plugins directory, and unzip it. This should give you a directory called ‘simpleressembed’ which has 3 things in it:

• an empty directory called ‘cache’
• a file called readme.txt
• a file called simplerssembed.php

Make sure that the cache directory is writeable by your web server, or whatever user that will be executing the php scripts. The safest way (on *nix system) is to do the following (assuming that the process runs as the user ‘apache’:

Then go to the plugins tool in your WP dashboard, and activate the plugin.

Using the plugin

Once the plugin is activated, you can embed RSS feeds with the following shortcode:

Parameters

The currently defined parameters are as follows:

Default values

The default values for the above parameters are:

Example output:

This is output from the actual code above:

Recently, I decided to upgrade the drives in my desktop. Since I don’t like the idea of downtime due to a failed drive (my desktop is also my home file server and firewall/router/dhcp server), I use software RAID1. The cost of an extra drive has been well worth the time saved from the last couple of HD failures I’ve had (including the lousy refurbished Seagate RMA drives). My initial array was 2 Seagate ST3750330AS (750GB, 32MB cache, 3Gb/s). They’re reasonably good drives, and I’ve had them for 4 years or so. For the same price I bought these drives for a couple of years ago, I managed to get 2 Western Digital WD1002FAEX-00Z3A0 (1TB, 64MB cache, 6Gb/s). So, a bit more space and faster drives. Now, the trick was to upgrade them without any downtime (other than the time to drives), or the need to resort to copying data off and/or restoring from backups (backups are important, but that’s another topic). In my setup, I have 2 drives (/dev/sda and /dev/sdb) which are combined to make 2 MD devices, /dev/md0 (my /boot partition, which is 100MB) and /dev/md1 (a physical volume used for LVM, and is the rest of the drive). Here are the steps I had to take to do this:

Step 1. Remove one drive from the array

Flag one of the drives as ‘faulty’ so that it can be removed from the array. In this case, I’m going to start with /dev/sda, but I could easily also use /dev/sdb. The command below will remove both partitions (sda1 and sda2) from their respected raid devices (md0 and md1) and set the drive as ‘failed’.

Step 2. Physically replace ‘failed’ drive

I then safely removed the ‘failed’ disk from my tower (kept is as a safety backup too), and replaced it with one of the 1TB drives.

Step 3. Copy partition data from old drive to new

I dumped the partition scheme from sda to sdb. This would have been more important if I was replacing the drive with an identical one (in the case of a drive failure). However, this would allow me to be sure that my md0 (/boot) partitions were the same size. IMPORTANT: Make sure you put the devices below in the right order, otherwise very, very bad things will happen.

If the above step looks too scary for you, then you might want to save the partition map to a file first, to at least have a chance of recovering it should you mess up. Here’s how:

Step 4. Replace 2nd partition with bigger one

Next I used fdisk to delete the 2nd partition so that it will be larger (almost 1TB instead of almost 750GB)

Now I’ve got 2 drives with 1 partition (for /boot) that is exactly the same size, and the second partition on the second drive is almost 1TB instead of 750GB. Software RAID is ok with this, and it will allow me to add both partitions to my previous RAID devices, however each device will only be the size of the smallest partition. I could have taken the opportunity to increase the size of md0 if I wanted to, but didn’t really need to.

Step 5. Update MBR for Grub

OK, this is going to assume you’re using grub as your bootloader and that it’s on the MBR. Since a drive has been replaced, this needs to updated otherwise the machine might not reboot.

Step 6. Add drive back to array

Next step is to add this drive back to the RAID array and rebuild.

Step 7. Wait, wait, wait

After that, I wait for the RAID to rebuild and show up in a 'clean' state. Since this is 750GB of data that needs to sync, it means several hours. So, I keep checking the state of the array until I see this: [root@mafalda ~]# mdadm --detail /dev/md1 /dev/md1: Version : 0.90 Creation Time : Fri Mar 14 23:36:49 2008 Raid Level : raid1 Array Size : 732467520 (698.54 GiB 750.05 GB) Used Dev Size : 732467520 (698.54 GiB 750.05 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Tue Nov 29 04:01:16 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : bad9d783:9b7b40be:9fd48ad3:7334f5c6 Events : 0.3555449

Step 8. Rince, lather and repeat

Repeat steps 1-7 using sdb instead of sda and vice versa.

Step 9. Resize the raid partition

After both drives have been replaced, the second RAID device is still only 750GB. It needs to be modified to bring it up to 1TB. This is the command to do that:

Checking the status of the device will show it's new size, and it's back to the waiting game.

Step 10. Resize the LVM physical volume

Now that the RAID device has been resized, the next step is to resize the LVM physical volume. The pvdisplay command confirms it:

Step 11. Adding adding the extra space to my /home partition

I've pretty much done all the necessary things that this post has set out to do. If I wanted to add 200GB of this data to say, my /home partition (the 'home_lv' logical volume in the 'mafalda_vg' volume group), this is what the commands would be:

[root@ ~]# lvresize -L +200G /dev/mapper/mafalda_vg-home_lv

Then I would need to grow the ext[2|3|4] filesystem, which can also be done online

That would effectively add 200GB to my /home partition. All done with minimal downtime (the time to swap physical drives).

I’ve often got things I’d like to share, or better still, discuss with other sysadmin friends, and Facebook doesn’t seem to do it for professional content, or for things that are worth keeping around – everything get lost in Facebook’s firehose way too quickly.

xzilla on #postgresql (irc.freenode.net) pointed me out to a recent blog posting of his that seemed to do what I wanted using Out parameters. This was really great, and I knew I had something I could work with there. Thanks xzilla!

So, I took it a bit further and modified his example slightly to see if I could also do it without the out parameters and just use the rowtype. Here’s the result:

CREATE TYPE footype AS (number int, oddoreven text);

CREATE OR REPLACE FUNCTION odd_or_even(int) RETURNS SETOF footype
AS $$
my @Return;
my $Count = 1;
my $Input = $_[0];

while ($Count <= 10) {
  if ($Input%2 == 0) {
     push @Return, { number => $Input, oddoreven => 'even' }
  } else {
     push @Return, { number => $Input, oddoreven => 'odd' }
  }
 $Count++;
 $Input++;
}

 foreach my $Row (@Return) {
     return_next $Row;
 }
 return;

$$ LANGUAGE plperl;

test=# SELECT * FROM odd_or_even(23)
test=# ORDER BY odd_or_even.oddoreven;
 number | oddoreven
--------+-----------
     24 | even
     26 | even
     28 | even
     30 | even
     32 | even
     23 | odd
     25 | odd
     27 | odd
     29 | odd
     31 | odd
(10 rows)

Now, my place is insured, so if it were to burn down, it wouldn’t leave me in the situation as some of the 50 newly homeless people mentioned in the article above. No insurance company will give fire/home/theft insurance to apartments above bars and restaurants (been there, tried that). Those guys are very unfortunate indeed. So, I could replace most of my belongings, but this did make me seriously look at improving my backups. I do have some of my backups off site, but clearly not enough, and I will be remedying this very soon.

Before my connectivity loss, we could smell the smoke, so I grabbed my camera and went out to see what’s happening. Here’s a quick description of things as they happened:

As I got to the end of my block, I could clearly see smoke, fire trucks and lots of activity. I could hear the sirens of more trucks coming from behind me. The smell of smoke was very strong and irritating enough for me to change my breathing pattern to avoid inhaling deeply.

When I got around to the West side of St. Denis (a very popular street in Montreal, full of restaurants and night-life), there was a small crowd of people watching the firefighters. Lots of people taking pictures with their cell phones and cameras. There wasn’t any real sense of danger (although, I suspect the people who’s apartments were on fire felt diffently), if anything, there was an air of excitement.

The smoke really started to get thick fairly quickly – this was getting really exciting! The EMT folks (ambulance, police and fire) didn’t seem to be too concerned about the crowd right across the street, and were happy to let us watch the action as it unfolded.

I don’t think I’ve ever seen so many firemen all in one place before. It was kinda neat to see them all up on the roof. At this point, they had all sorts of saws, axes and prybars out, ripping open mouldings and flashings. Still no sense of real danger in the mob, but people were starting to realize that this was a big fire.

In the next photo, you can barely see a hit of orange behind the cherry bucket. Right before this, the smoke got noticeably darker. Once the flames were visible, the mood down in the crowd changed quite dramatically. People were clearly concerned for the safety of the firefighters, some of whom seemed to have been taken off guard as they scattered to the edges of the building. There were a number of gasps as the onlookers got more worried when the flames started shooting 10 – 15 feet up out of the building.

With flames clearly visible now coming out of the front window, the EMT guys realized that perhaps having a crowd across the street wasn’t a good idea. They started telling everyone to move along – most of us just stood there and watched anyway. Zooming in on the window, you can see that the room is largely consumed by flame.

It didn’t take long for the heat to break the closed windows. Along with the very dark smoke that was released, the sound of the windows shattering and glass falling to the sidewalk was clearly audible despite the fact that there were dozens of alarms and sirens going off. Many of the alarms were from the warning mechanisms on the firefighter’s air supplies as they came down the ladder to cool off in a makeshift shower and get new tanks.

Once the windows were broken, the fire really managed to burn hot! The plus side was that a hot fire burns more and makes less smoke. Now the EMT folks were starting to get a little more serious about getting us out of there as we could clearly feel the heat across the street even though we were upwind. Watching this made me think of the classic line from an old Eddie Murphy standup skit, where his pyro uncle says “Now, that’s a fire!” after nearly burning down the back yard lighting the BBQ.

The flower pots in front of the windows were now melting, and the dripping plastic burns as it falls. From our view, it looked like dripping flames and was quite interesting to watch as it burned whatever it lands on. Our side of the street was now getting really hot, and the police were now actively putting up barricades and telling people to get further back. I could hear them coming, and they were starting to get annoyed that people weren’t listening, but I wanted a couple more shots.

Despite the fact that there’s a huge fire right next to them, these firefighters stick to the task at hand and do what they can to save the structure next to it. I can’t imagine how hot that was for them, considering what we could feel across the street. According to the reports the next day, 4 firefighters suffered heat exhaustion and one had minor burns. The crowd was really worried about them and we were all hoping the hoses would start as there were still no signs of any hosing at the front yet.

Eventually, we were all forced to leave the area and the police barricaded the entire block. I went back home to unload my camera, and came back to take more photos and watch as they got out the hoses. By this point, my ‘net, cable and phone were no longer working.

The next day, it was clear that the building that had L’Barouf and The Continental was completely destroyed. The owner of The Continental vowed to rebuild in a bunch of newspaper and TV interviews. The ironic thing is that the fire started in the grey building to the right, which seems to have suffered way less damage. Apparently, the cause was electrical, not a surprise seeing how some of these places are wired.