Making custom power cables (by alaric)

I take great pleasure in making custom power cables for things. It's very satisfying.

Lately, I've been having fun with this. Firstly, I was frustrated when visiting a datacentre that had only IEC power connectors, rather than UK standard 13A sockets - there was nowhere to plug my laptop in.

So, I've made a special adaptor cable:

Job done!

Nextly, at work, we have two 16A managed power distribution units, which have 24 outlets on them, each individually controllable via the network. They're lying around, surplus to requirements. We also have two 32A units in use in the racks - and more than 24 devices that need plugging into each.

Now, the outlets are mainly IEC C13 ten amp ones, but there's a small number of IEC C19 sixteen amp outlets, so we struck upon the crazy idea of attaching the 16A units to the 16A outlets on the 32A units. Thing is, the 16A units have 16A industrial plugs on them - not C20 plugs that go into C19 outlets.

So, once again, I made an adapter cable:

Well, two identical adapter cables, to be precise.

Lots of fun.

Fixed network access from PHP apps – but broke WordPress even more… (by alaric)

I upgraded to PHP5 from PHP4, in desperation, and lo, PHP apps can now once more connect to the network.

I'd gone as far as to ktrace an httpd process running a PHP app, and found that it produced an identical syscall trace to PHP run from the command line - up until it tried to read back from the socket, whereupon it gave a one-byte buffer, so read only the first byte, then hung thereafter. While when run from the CLI, the same PHP code gives a buffer of 0x2000 bytes and works fine.

So, I tried the one last thing I could think of (having failed to manage to convince gdb to attach to a running httpd child process) and moved to PHP5.

And, wow, it worked!

At the cost of breaking all our WordPress blogs. They don't show article bodies any more, and output endless complaints to the error log.

Still, now outgoing network access is fixed, webmail works again, my RSS aggregrator works, and it's just occured to me that the recent overwhelming flood of blog spam I've had has probably been due to Akismet being unable to reach its server!

Big server upgrade! (by alaric)

Whew. I'm just in the final stages of migrating love.warhead.org.uk's backend storage over to a new (much bigger and faster) server.

This stage consists of poking at the things that aren't working right, and finding out why.

For example, my blog seems to be showing the very first posts we ever made to it on the front page...

Apps as containers (by alaric)

As I have mentioned before, it annoys me that many applications try (subtly or otherwise) to appear as the 'containers' of your data; they are both editors of a particular type of object, and a browsing/management interface for that type of object. The insidiously widespread case being applications that have 'Open' and 'Save As' menu items that pop up mini filesystem browsers, only showing the types of documents that application cares about and hiding others.

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Is it normal to want to assign every object you own a serial number, then keep a database? (by alaric)

I've been doing some systems work in a rack recently that uses redundant systems. Two optical fibres come into to two switches which are connected to two routers and two load balances, and every server has two or more network interfaces (since there's internal and external VLANs).

So there's rather a lot of cables in there! Since the spare length is all neatly bound into a bundle, finding the other end of the cable you're looking at is a bit of a pain.

So I'd like to number each cable, label each end of the cable with its number, and add cable numbers ot the "what's in what port of which switch" spreadsheet.

Most cable marking systems, however, have to be applied before the plugs are attached to the cable - since they involve a sleeve that goes over the cable. This isn't good, since I want to label existing cables.

Hunting about online, I found these folks who do a nice line of markers - including the PC range of snap-on markers for existing cables. Lovely!

They've sent me a pack of samples, so I can experiment to see what fits best on my cables:

...and it looks like PC40 is the best size for CAT5 UTP.