So we are on an Apple Network here. But rather than relying on time machine as a backup solution – which isn’t really the way to go for multiple machine backups – we’re using Retrospect. (I could write a novel about the grief that piece of software has caused me – but why bother?). And while we ran our backups for yonks onto DVDs, the stack of media just took on ridiculous dimensions. That is why we installed a NAS (LevelOne FNS-5000B, good hardware, but shoddy interface, should have gone with a QNAP), with two 1.5 Tb hard disk in a RAID1 configuration. The NAS offers multiple protocols to connect to the network.

Retrospect is maintaining its backup files via the network on the NAS. And out of convenience (and for security reasons) we also keep older backup sets on the NAS. Now some of our guys have the Retrospect software (not just the client) installed one their machine so that they can access and retrieve files from historic backup sets.

And that’s where we encountered problems on a random basis. Sometimes on the Macs Retrospect simply refused to accept the backup files on the NAS as valid Retrospect catalogues. In the finder, the files did not show up with their usual icon, but instead featured the wee terminal icon. Apple-I showed the files as “Unix Executables”. Strangey enough, this problem would occur on some machine one day, but would be miraculously fixed the next day. If it did not fix itself I used to fix the issue by using a tool called FileType to change file type and creator codes. However, for some reason that did not work more recently. Plus I never felt quite comfortable fiddling with the backup set files anyhow.

So I did a bit of research and found that the “Unix Executable” problem has something to do with Macs not being able to “read the file’s resource fork“. So I asked myself, why the resource fork was readable one day, but not the next and I figured that it might have something to do with the network protocoll the Macs were using to access the NAS.

Sure enough, when the problem reoccured today, I did an Apple-I and found that the NAS was mounted using the Samba protocoll (smb://nas/). Now since the NAS also support AFP I wondered whether connecting via that protocol would fix the problem.

So I unmounted the NAS volume on the Mac (by clicking the eject icon next to the volume name in Finder) and then rather than using the Finder to re-connect to the NAS, I pressed Apple-K to get to the Finder’s  “Connect To Server…” window and typed in afp://192.168.1.* (i.e. our NAS IP). The NAS remounted into my finder and – voila! – gone was the “Unix Executable” problem.

Why the Macs sometimes connected via smb and then again via afp is beyond me. But at least now I know how to fix the problem.