I expanded my RAID from 9TB to 13TB, and after it had finished, I noticed I had to resize the partition in order to use the new space. When I used Disk Utility, I got an error saying "Partition failed with the error: MediaKit reports partition (map) too small." After googling, I found the solution on the "life as i know it" blog, and thought I'd share the basics of the solution.

From the blog post, here's the essence of the problem and the solution:

Basically what’s going on here is that the GPT table is built only big enough for the drive it’s on. That’s a logical assumption - hard drives don’t magically get larger - unless they’re RAID arrays. We’re just removing the GPT partition information, and replacing it. Should things go crazy, as long as you’ve got the start and size information for the partition you care about, you should be good. No guarantees obviously, but I’ve done this three times and no data loss yet.

Read on for a summary of the fixes involved, and see the blog post for more details...

If you installed the latest version of Drobo Dashboard (currently v1.6.1) on Snow Leopard, and you're also unfortunate enough to have a Intel Mac that doesn't support 64-bit, then you might notice a drop in performance of your Drobo, and possibly your system altogether.

Check your Console logs. If you see something like this... ...then the Drobo installation software installed the 64-bit binaries and kexts, even though your machine doesn't support them. Here's how I fixed it.

A small number of users lost the use of their older FireWire 400 disc burners (and perhaps other FireWire peripherals) after installing Snow Leopard. I have a fairly new Pioneer DVD burner installed in a circa-2001 LaCie enclosure, and I was one of the victims. The 10.6.1 update did not address this issue. Until Apple remedies the situation, here is a solution that works without any obvious side-effects:

Locate IOFirewireSerialBusProtocolTransport.kext in /System/Library/Extensions, and store it in a safe place. Replace this item with the same extension from Mac OS X 10.5.x Leopard. The date stamp on my copy was October 9, 2007. (You may still have a copy in your Time Machine backup.) After replacing the file, use Disk Utility to Repair Permissions. This step is vital, or else the replacement extension may not be recognized by the System. Finally, restart your Mac.

After the restart, if your FireWire drive worked properly under 10.5.x, it should work fine again.

NOTE: This hint involves mucking around in your System folder. Appropriate precautions are in order. Do not perform this operation if you are not experiencing issues with your FireWire devices. I did not originate this hint; it came to me as an anonymous reply to a message I posted to several places on the 'net.

Snow Leopard has the ability to mount NTFS volumes as read/write, but it's not enabled by default -- just read only is supported, as in 10.5. Here's how to get full read/write support for NTFS drives in Snow Leopard. First, uninstall NTFS-3G or Paragon if you're using either one.

Here's how to get read/write support for NTFS drives in Snow Leopard:

1. In Terminal, type diskutil info /Volumes/volume_name, where volume_name is the name of the NTFS volume. From the output, copy the Volume UUID value to the clipboard.
2. Back up /etc/fstab if you have it; it shouldn't be there in a default install.
3. Type sudo nano /etc/fstab.
4. In the editor, type UUID=, then paste the UUID number you copied from the clipboard. Type a Space, then type none ntfs rw. The final line should look like this: UUID=123-456-789 none ntfs rw, where 123-456-789 is the UUID you copied in the first step.
5. Repeat the above steps for any other NTFS drives/partitions you have.
6. Save the file and quit nano (Control-X, Y, Enter), then restart your system.

After rebooting, NTFS partitions should natively have read and write support. This works with both 32- and 64-bit kernels. Support is quite good and fast, and it even recognizes file attributes such as hidden files. My thanks go to Chrysaor, a MacRumors user who brought this to our attention.

[robg adds: I haven't tested this one, as I don't have any NTFS drives on my Snow Leopard machines. There may be good reasons why Apple left support disabled, so use at your own risk. Mac OS X Hints reader Jakimowicz submitted a similar hint which pointed out the free NTSF Mounter utility, which lets you enable read/write on NTFS volumes via a simple GUI.]

When buying a new DVD burning unit, I didn't waste a second on compatibility issues with Mac OS 10.5. Instead, I bought the first DVD burner available for around 20 Euros: A LG Electronics GH-22NP20. I attached it externally with an Delock Converter USB 2.0 to SATA/IDE.

First tests works quite well -- DVD and CD reading, and even CD burning, works with Mac OS 10.5's integrated software and drivers. But serious problems occurred when trying to burn a standard DVD: The burning software, Burn.app in my case, ends with an error stating the disk capacity is exceeded, regardless of the size of the files to burn. There are a lot of fine burning apps for free on the market, but non of them seem to work.

After digging around in the net, I came to the conclusion that this burner is incompatible to Mac OS 10.5. A lot of users have the same problems -- take a look at this Apple Discussions thread, for example. The only solution that seems to work: buy a version of Toast. I know this is an excellent piece of software, but really, buying software for about 100 Euros to run hardware that cost 20 Euros?

My first thought was to replace the LG drive with another Mac OS X-compatible one. But then I remembered a solution coming from the UNIX-side of Mac OS X. I gave it a try and it worked. Don't fear the Terminal (located in the Utilities folder in the Applications folder!). Read on for the solution in detail.

Note: Please see comments for a safer method of doing this!

Have you ever been annoyed by those ugly capital letters in your USB drive's names? Well I was and here's how I fixed it:

1. Locate your device: Open up Disk Utility and select the drive. Click on Info, and copy the device name, e.g.: disk2s1.
2. Deactivate the disk (Do not Eject it).
3. Open up a Terminal window, do a hexdump on the device name you just found, and grep for the current volume name:

   $ hexdump -C /dev/disk2s1 | grep "Pablo"
   00000040  80 00 29 08 ac 67 54 50  61 62 6c 6f 27 73 20 4b  |..).?gTPABLO'S K|
   010000e0  50 61 62 6c 6f 27 73 20  4b 65 79 08 00 00 18 bc  |PABLO'S KEY....?|

4. Create a text file containing the new label: echo "Pablo's Key" > input
5. Replace the old label with the new one using dd:

   $ dd if=input bs=1 count=11 seek=0x47 conv=notrunc of=/dev/disk2s1
   $ dd if=input bs=1 count=11 seek=0x10000e0 conv=notrunc of=/dev/disk2s1

   Note: Set the count value to the label's length. Remember that a FAT drive label cannot be longer than 11 characters.
6. Run a new hexdump to verify:

   $ hexdump -C /dev/disk2s1 | grep "Pablo"
   00000040  80 00 29 08 ac 67 54 50  61 62 6c 6f 27 73 20 4b  |..).?gTPablo's K|
   010000e0  50 61 62 6c 6f 27 73 20  4b 65 79 08 00 00 18 bc  |Pablo's Key....?|

And as always, proceed at your own risk and back up any data on the drive before proceeding. You can find more detail on this, including some screenshots, in this MacRumors forum thread.

Like many others, I used Disk Utility to create a disk image (.dmg) from my full disk, with the expectation that I could restore this backup at a later date. Said date came all too soon, and I found myself accused by Disk Utility of offering it a corrupted image. Much investigation and much research followed: the image was not corrupt, but the graphical tools did not allow a multi-partition .dmg file to be restored, nor did they allow a full-disk .dmg file to be written to a raw disk or a block device.

Luckily for us all, this task is possible! I hope to spare you much of the suffering I experienced with this hint. For this occasional task, the hdid utility is your friend. You must use Terminal, as Disk Utility does not support this use.

First, mount the .dmg file as a block device only:

hdid -nomount "/Volumes/Diotallevi/Clean Checkpoints/WDC Image.dmg"

Second, determine the block device of the image and destination:

diskutil list

Third, use dd with an appropriate buffer size to copy over the whole block image, including partition table and boot sector. Note that it is extremely important on some hardware to use a large block size; you can expect a 20x speedup over the case without blocksize parameter.

dd if=/dev/disk3 of=/dev/disk2 bs=131072

Fourth, unmount everything and enjoy your copied disk. I get around two terabytes a day of transfer rate; I know of no way to skip sparse areas of the disk image, but could approximate it by dding the first few megabytes of the image, then using Apple System Restore to copy each volume individually.

Expect large speedups for sparse disks with this method. (This hint originally appeared on my site.)

I had problems getting disk sharing using Time Capsule and Back to my Mac to work. I was able to see the Time Capsule in my Finder's sidebar and everything worked fine when I was on my network. However, when trying the same over the internet via Back to my Mac, I was able to see the Time Capsule in the Finder sidebar, but any attempts to connect to it would simply time out.

After searching the net and coming up empty, what I realized was that I had IPv6 Mode on the Time Capsule (Airport Utility » Manual Setup » Advanced » IPv6 tab » IPv6 Mode setting) set to Link-local Only. After changing that to Node and letting IPv6 be configured automatically, things just started working...

I couldn't find this documented anywhere, and hence the hint.

A problem with some of the Western Digital's My Book external hard drives is that they have a spin-down functionality built into their firmware. Meaning that no matter what preferences are set in System Preferences, if 10 minutes of inactivity have passed, the hard drive will go to sleep. This is annoying, as even if you are browsing files in the Finder without looking at the ones on the hard drive, the Finder triggers a spin-up, and then bogging down the system until the hard drive has finished spinning up.

A workaround for this is to not let the hard drive be inactive for more than five minutes by constantly touching a hidden file on the hard drive. This is done by first building a small script in bash that touches the hidden file and that also checks if the hard drive is mounted, so as to not flood the system logs if the drive isn't connected. Here's that code:

#!/bin/bash
# Used to not let a volume named MYBOOK sleep

volpresent=$(mount | grep MYBOOK | wc -c)

if [ $volpresent -gt 0 ]
then
    touch /Volumes/MYBOOK/.hiddenfile
fi

This script should be made executable by running the following on the Terminal: chmod +x ./no_sleep_script.sh. Replace no_sleep_script.sh with whatever you named the script. The best way to run this script every five minutes is to use the launchd system built into Mac OS X, and a donationware app called Lingon is a great tool to manage it.

Install Lingon, then build a new Agent in the My Agents category, choose a unique name for it (such as com.username.agentname), input the location of the script, and tell it to run it every five minutes. Save it and restart your session. I've done this and the drive has remained sleepless since.

It can be argued that this may shorten the life of the HD, but from what I've read in various forums, having the HD spinning down and up constantly also causes severe strain on the HD, especially in situations like mine where the HD is constantly on. DISCLAIMER: This is not really my hint, but a variation of someone else's, but I don't remember where I got it from, sorry!

Twice now I have had problems formatting a new Western Digital My Book external drive under 10.5.x. Disk Utility fails to format the drive as Max OS X Extended Journaled with a "Format failed..." message. The first time this happened, I found an obscure firmware update at Western Digital's forums. This time, I found a quicker solution in this thread over at macForums. Here's a short executive summary version:

1. Open Disk Utility and select your drive.
2. Go to the Partition tab, name the drive as you wish, and choose one partition. Partition the drive.
3. Select the partition you just created. Go to Options (on the bottom of the dialog window) and select GUID Partition Table/OK, then click Apply.

That's it; you can now format the drive successfully.