For the last three years (i.e. before Time Machine), I have been using rsync to make incremental backups to an external FireWire disk from my trusty iBook. Now, rsync does this by backing up into a fresh location each time and referring to the previous backup to check if any data can be de-duplicated, which it does by creating hard links.
rsync -a --link-dest=$PREVIOUS_BACKUP $SOURCE $NEW_BACKUP
A wrapper script is needed because rsync doesn’t do any rotation of the backup paths (mine preserves six previous backups, which is quite enough), but overall the solution is elegant – restoration from any given backup is just a cp -pR away, due to the transparent nature of hard links. However (and this is the important bit) rsync only de-duplicates when the source file is identical to its previous backup in every way, including metadata.

As time went on and my laptop drive started getting full, I found that the backup window was getting suspiciously long for an 80GB disk. But it was the lack of space that finally drove me to buy a bigger external drive (admittedly, backups aren’t the only thing taking up GB on my FireWire farm).

Finally I ripped apart the wrapper script and dug through the previous backups. Turns out that rsync wasn’t preserving all the metadata, specifically file ownership. Google, as ever, gave me the answer:

Official Google Mac Blog: User 99, Unknown

By default, OS X silently maps all file ownership on external HFS+ disks to a special user “unknown”, while pretending to the user that he still owns the files. This is a “feature” to prevent weird permissions problems when swapping external drives between machines. It is so low-level that not even root can override it – if you try as root to chown a file on an external HFS+ filesystem, it will silently do nothing.

The upshot is that rsync didn’t believe that any backed-up files were identical to their originals, and so didn’t de-duplicate anything. Instead of six lean incrementals, I have six wasteful bulk backups, some of them incomplete because I ran out of backup window. And all the file ownerships have been lost, so a system restore would have failed spectacularly – if I had been foolish enough to try.

You can turn off this behaviour for any given disk (Finder>Drive>right-click>Get Info>uncheck “Ignore ownership…”), but it’s a bit late now.

A group in the US has taken out a lawsuit to try to prevent the Large Hadron Collider starting up. Why? Because it might destroy the earth, of course.

Particle smasher ‘not a threat to the Earth’ – opinion – 28 March 2008 – New Scientist

I hate to say it, but that’s what happens when popular science magazines blindly give credence to any old nonsense wittered by someone with a science degree. Planet-eating particles, my arse.

In my current job, Microsoft Sharepoint rules. The decision was made long before my time to employ it as the common document repository, and for most people it works reasonably well. I have to force myself to use it though, and I can distil the reasons down to one root cause: ActiveX controls.

In its vanilla, static-page form, Sharepoint is barely functional. It takes a minimum of four clicks (open, edit, modify, save) to change a radio-button option. Checking files in and out is a pain – it’s easier to just overwrite. And I’ve never managed to attach a file to a list entry. To make it really useable, you need to run IE.

Oh wait, you’re using a Mac. Well you can just piss off then.

It’s interesting that Microsoft poured thousands of programmer-hours into developing an alternative to JavaScript and not one of the other browsers makes any attempt to support the resulting spec – this in a world of Mono, Samba, Moonlight and OpenOffice. MS dropped IE support on the Mac but keep pushing ActiveX in their server products. I’m no expert, but the only thing I see ActiveX doing that JS can’t is installing software updates without bothering the user with dialog boxes. Which is a good indication of why nobody else will touch it with a barge pole.

The problem is not confined to Sharepoint. The motivation for this post was finding that Microsoft’s certificate management server requires scripting to be turned on (it doesn’t say what sort of scripting, but it isn’t JS) in order to process a simple form that could have been written in 1995. In this case there was no option but to boot up the VM and use IE.

So what to do? Struggle manfully with Sharepoint’s prehistoric static interface or retreat into the VM, cut off from my usual editing suite – Office X for Mac. Somebody somewhere is no doubt enjoying this juicy irony. But it’s not me.