Birds Like Wires

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Failed Core Storage Conversion

We have a Mac mini connected to an external storage box via FireWire. In a reasonably sensible manner, someone pointed Time Machine at one of the volumes on the DAS, thinking they should back the machine up to this location. They also thought also it would be best to encrypt the backup; very laudable.

However, this triggered a conversion process into an Apple Core Storage volume, which did not complete successfully. Luckily, OS X stopped trying and remounted the volume as HFS+. All appeared to be well, but after a reboot things were much less cheerful.

On restarting the machine, the volume was missing. Checking with diskutil list returned this layout:

   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *17.6 TB    disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:                  Apple_HFS Backup                  2.0 TB     disk1s2
   3:          Apple_CoreStorage                         15.6 TB    disk1s3
   4:                 Apple_Boot Boot OS X               134.2 MB   disk1s4

But diskutil cs list returned this:

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Mac Pro Storage Upgrade

An SD-PEX40079 with three 256GB Crucial m550 mSATA drives attached.

I’ve been slowly changing my storage habits lately, because I’ve been seduced by the speed of Solid State Drives. When I bought my Mac Pro, I got it with the extortionately expensive Apple SSD. It’s as solid as a rock, and the only thing out there with official TRIM support, but it’s not the speediest option and that’s largely down to the measly 3Gb/s SATA II bus that Apple forgot to upgrade with the 2012 edition. Seriously, guys, you couldn’t have swapped out that controller?

However, because these Mac Pro machines are proper tower systems with PCI-E 2.0, there are options out there. For a long time I was going to go with the Sonnet Tempo SSD Pro (or the Pro Plus as it’s now become) but blimey, at over £200 it’s an expensive way of putting SATA III in your machine. And eSATA is a lovely feature, but not already owning any eSATA caddies, I just didn’t think I’d use it that much.

A little Googling turned up this thread on the TonyMac forum, where ‘gsloan’ had found success with the Syba SD-PEX40068. But would you believe it; discontinued. Nuts.

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Caching Server Cache Size

The Caching Service in OS X Sever is great – turn it on, and it largely works just fine. However, I host the cache itself on a Drobo. The Drobo appears as a 16TB volume on the system, so thinks it’s just a wonderful idea to give me Cache Size slider graduations of 30GB, 1TB, 2TB, etc. That’s not helpful.

Luckily, Apple haven’t obfuscated the configuration for this at all, and I’m not being sarcastic for once. Just go to:


You’ll find the CacheLimit key right there at the top, with an integer value in bytes. Turn off Caching Server, edit, turn Caching Server back on again. Lovely.

Screenshot of showing the Caching Server config panel.

Okay, so the slider shows the wrong value, but the Usage area gets it right. Now why couldn’t they have just put a box in the UI? Ah, because this is, not Server

My sarcasm is creeping back!

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Command Line Wireless Options in OS X

Managing OS X wireless options was a terrible mystery until I discovered the magical hidden ‘airport’ command. If you do any Mac sysadmin work, I recommend:

sudo ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport /usr/sbin/airport

This gives you lovely, straightforward access to the airport command, from which you can turn wifi on and off, configure administrative settings; basically everything you need. However, watch out; there’s been a change in the version currently shipping in Mavericks. My fave command was:

sudo airport en1 prefs RequireAdmin=YES

But this will no longer work. Instead you receive this response:

'Unrecognized prefs option 'RequireAdmin=YES'.

It’s not a problem, because Apple have actually unpacked the RequireAdmin option into it’s three constituent parts; RequireAdminIBSS, RequireAdminNetworkChange and RequireAdminPowerToggle. You can now control each of them individually.

So my favourite command has now become:

sudo airport en1 prefs RequireAdminIBSS=YES RequireAdminNetworkChange=YES RequireAdminPowerToggle=YES

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The Dell 1320cn Printer and OS X

'Dell Color Laser Network Printer 1320cn' by Cheon Fong Liew

Do you have a Dell 1320c or 1320cn? And a Mac? Are you tired of not being able to print? Fret no more!

The drivers from Dell are stuck way back in the Tiger (v10.4) and Leopard (v10.5) days and I’ve had no end of trouble with them. But, as is so often the case, the hardware inside that Dell printer isn’t really Dell at all. What you actually have is a revamped version of the Fuji Xerox DocuPrint C525A.

Luckily, Fuji Xerox are rather more amenable to keeping their drivers driving and their printers printing than Mike’s company is.


You could install the drivers directly from Fuji Xerox, but why bother? Apple have already rolled the drivers into a snazzy package that will auto-update when new versions are released. Head over to the FujiXerox Printer Drivers page on Apple’s website, download and install the printer driver package. This works on the latest Mavericks version, all the way back to Snow Leopard.

Screenshot of the Fuji Xerox C525 A-AP v3.2 printer driver being installed for a Dell 1320cn printer.

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Tunnelbroker and Dynamic IPs

Change of plan! While the details provided here are accurate and may well be useful if you’re configuring ddclient, I found issues updating my DNS information this way. So I opted for something much simpler, which I’ve written up here.

My shiny new router, which I’m hoping to write a proper article about soon, supports IPv6 tunnelling. IPv6 is going to become increasingly important over the next decade, as we’re running out of IPv4 (the ones that look like addresses to give to all of the devices out there. Internet service providers are going to need to pick up the pace of handing these out, but in the meantime for those that don’t (such as BT) there are tunnelling services.

An IPv6 tunnelling service does basically what it sounds like; shoves your IPv4 traffic through a tunnel so that it pops out of the other end with a valid IPv6 address. You can then access services that only use IPv6… okay, that’s not many right now, but hey – you’re future proof! There are a few different providers out there, but I use Tunnelbroker. If your router supports it, you can configure the entry point to the tunnel from the details Tunnelbroker provide and pow! You’re accessing IPv6 sites.

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Fix Postfix for Gmail on Snow Leopard

This is a quick and dirty method for getting Postfix (as built-in on Mac OS X v10.6) to send mail via Gmail.

My little home server is a tweaked Mac mini, but Snow Leopard is the last version of OS X that will work on it without even more hacking around (besides, it’s the best version of OS X Server, IMHO). I had a search around on the web and after combining a few different methods, came up with this to make it work.

Sort out Certificates

Google changed to using Equifax as their certificate signing authority some time ago, but Postfix doesn’t know about them. So, you need to add their certificate (and we’ll add Thawte at the same time, for good measure).

Start by creating a certificates directory:

sudo mkdir /etc/postfix/certs

Jump into it and create a file called Equifax_Secure_CA.pem, then copy the following into it:


Then you need to create the Thawte one as well. Call it Thawte_Premium_Server_CA.pem.

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Mac OS X Server and DNS

I’ve just bumped into this little chestnut again, and thought it would be worth documenting quickly, once and for all.

If you run Mac OS X Server, the one thing that is more important than anything else is to make sure the DNS hostname is set correctly. It’s fundamental – everything breaks if it’s not working. Out of the box, Server even configures its own DNS server to make sure the details are correct.

Now, I run my own internal DNS using Mac OS X Server, just so I don’t need to remember IP addresses. However, after adding an address to the DNS yesterday, the hostname of the server magically changed. I didn’t ask it to, it just happened. It was time to break out the repair tools.

Three Commands Will Save You

They are changeip, scutil and dscacheutil. Remember them, because they are your only friends. If the DNS is iffy, Server Admin runs away and needs some coaxing to play again (which, of course, is really helpful).

First, make sure that your IP address is correct. Please tell me you’re using a static IP? Yes? Good. If that’s not the issue, fire up and find out what’s going on. My first hint was that the hostname next to my command prompt had changed, which is a pretty big clue. Run:

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Moving Apple Software Update Files

Here’s a fun one. You’ve set up Software Update Server on your Mac OS X Server system and all is fine. Then you realise that you’re the proud owner of a directory containing 52GB of software updates and you’ve put it in a silly place.

You shut down Software Update in Server Admin and move the directory to a bigger drive. You reconfigure the path and then re-enable the server. You see from the logs that all is well and you fire up Software Update on your client machine.

Hooray. That’s not quite what we were aiming for.

Foolishly, I have in the past simply resigned myself to ‘fixing’ this by deleting the software update directory, recreating a blank one and erasing all of the configuration files in /etc/swupd. This is a silly thing to do as you’ll end up downloading that 52GB all over again. It turns out the solution is ridiculously simple.

sudo rm <path to swupd cache>/html/index*

This removes the various .sucatalog symbolic links which are still pointing towards your original software update directory. Software Update Server isn’t clever enough to repair these if the directory is moved, but it is clever enough to recreate them if they’re not there.

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Menu Extras and MCX

There’s a little quirk when you’re controlling menu extras for Mac OS X client systems using MCX. Well, there’s more than one quirk, but you know what I mean.

By default, new users of Mac OS X systems get Blutooth, Time Machine and Volume menu extras, as well as the clock. The Spotlight control is separate, so we won’t mention it here. On our systems I don’t really want to display the Bluetooth menu extra, we don’t use Time Machine and the volume is controlled by the external audio interfaces, so they could all do with going away.

An unmanaged menu bar in OS X

Digging through ~/Library/Preferences/ByHost shows that this is handled by a configuration file called and as such you can control what appears using the configuration options in Workgroup Manager. The key you’re after is sensibly named dontAutoLoad, which can contain the paths to any Menu Extras.

The simplest way to configure the behaviour is to set up a user as you like it, then import the .plist file into Workgroup Manager using the ‘+’ on the Details tab of Preferences. Just make sure you import with the ‘Import as ByHost preferences’ button ticked. Reboot, log back in to the managed client and…

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Mac OS X Lion and Xterm

If you’re running Lion as your desktop OS, you may well have bumped into this little one already. If you try to use commands such as nano or top or many other normal things, you may well be getting this error.

Error opening terminal: xterm-256color.


It happens because there is no file defining a 256 colour session in Snow Leopard, or Leopard, or Tiger for that matter. You’re even likely come across the error when SSH-ing in non-Mac systems. So how to solve it?

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Mac OS X Energy Scripting

We’ve got a variety of Macs running OS X versions 10.4, 10.5 and 10.6. They’re all managed from an Xserve with MCX preferences through Workgroup Manager, but for some reason I’ve just never managed to get them all to settle nicely with their power management settings.

While it’s lovely to have the control of these things through Workgroup Manager, I finally got miffed with it not working, particularly with the Tiger clients. It’s also not good to have rooms of machines burning away power and their components pointlessly.


So I did what I usually do. Write a script. There’s an excellent blog called Managing OS X which had already covered this issue, so using GregN’s script as inspiration I came up with this, in Perl for some reason.

Loading ‘’ from GitHub...

The idea is that this runs via launchd however often you would like. Using Lingon to create a .plist file, I have it triggered every hour. It uses the hostname of the machine to determine where it is, with different rules applied if the system is a ‘cluster’ or a ‘studio’ machine. Once per boot it reapplies the power management policy, and on every run it examines the state of the machine and decides whether it should be powered down.

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