Time Machine error (caused by Mac OS X Lion)

My Time Machine did not work today. I saw the following message:

I tried rebooting my mac and reformatting my external disk. They did not help. My external disk looks very healthy. There must be something wrong in Time Machine software.

In order to see what happened, I ran this command in the terminal window:

sudo grep backupd /var/log/system.log

I got many errors like this:

Mar 12 09:21:50 localhost com.apple.backupd[432]: Error: (-36) SrcErr:YES Copying /.DocumentRevisions-V100/PerUID/501/1/com.apple.documentVersions/074F6D28-7E46-4BBD-A877-7896143B9D1A.rtf to (null)

/.DocumentRevisions-V100 was created by AutoSave feature of Mac OS X Lion. I recalled I installed Lion on another partition and saved a file on Snow Leopard partition (to test AutoSave). Lion created that hidden folder on Snow Leopard partition and put the auto saved files there. However, the Time Machine software on Snow Leopard is not updated. It cannot recognize that system folder.
It is easy to fix this Time Machine error. Just exclude that hidden folder in Time Machine Preferences. (You need to enable 'Show invisible items'.) I actually excluded the following 3 hidden folders:/.DocumentRevisions-V100/.MobileBackups/.Spotlight-V100
My Time Machine is working again!This command "sudo grep backupd /var/log/system.log" is very helpful.

Exploring Mac OS X Lion (3): Versions and Auto Save

1. Versions

Versions is really a revolutionary feature of Mac OS X Lion, though it is not as obvious as Mission Control and Launchpad.

The system records every change to a file automatically. You can browse versions and revert your changes if necessary.

If you create a new file in TextEdit and go to File menu, you can see Save menu item.

But after you saved your file and make some changes, that menu item will be changed to Save a Version.

Exploring Mac OS X Lion (2): Trackpad Gestures and Mission Control

Looks like Lion depends heavily on trackpad gestures. You can use gestures to scroll view, show Launchpad, switch desktop, switch full-screen applications, show Mission Control. Mission Control could be considered as an enhanced Exposé.

I listed all gestures on Lion.

1. One Finger

Snow leopard: Tap to Click, Dragging, Drag Lock, Secondary Click

Lion: No change

2. Two Fingers

Snow leopard: Scroll, Rotate, Pinch Open & Close, Screen Zoom, Secondary Tap

Lion: little change. In Safari, two fingers swiping left/right means showing the previous/next page. In Snow leopard, you need to use three fingers to swipe.

3. Three Fingers

Snow leopard: Swipe to navigate.

Lion: Mission Control.

Swipe horizontally to switch desktop, dashboard and the full-screen apps.

Exploring Mac OS X Lion (1): Launchpad

In Mac OS X Lion, there is no icon of "Applications" on the Dock. Launchpad replaced it. Launchpad looks exactly like the springboard on iPad. You can make 4 fingers pinch to activate it. Launchpad supports pages and folders. You can drag an icon to rearrange it and drag it out of current page to create a new page. I tried clicking an icon and holding for a while, but did not see icons shaking.

However, Launchpad on an external big monitor is not beautiful. The icons are too big. It is not comfortable to see so many big icons on the big monitor.

The users who are using 3-button mouse will have a problem. They cannot switch pages of Launchpad. I think it is a bug.

The dock does not show indicator lights for the running applications by default. You can enable it in System Preferences.

Steps to install Mac OS X Lion on external hard drive

Apple just released Mac OS X 10.7 Lion developer preview. There are some new features inspired by iPad. The Launchpad looks like iOS springboard. The apps can run in the full-screen mode. You macbook with Lion will look like an iPad.

However, many people including me only have one machine with Snow Leopard installed. We don't want our valuable data destroyed by the beta OS. It is not safe to upgrade the existing OS to Lion in the existing partition. Can we just install Mac OS X Lion on the external hard drive? Yes!

Steps to install Mac OS X Lion on external hard drive:

1. Plug in your external hard drive to your Mac.

2. Open Utility->Disk Utility. You should see your external hard drive in the left view.

3. Choose your external hard drive (not the partitions) in the left view.

4. Choose Partition in the right view and create an GUID partition with Mac OS Extended (Journaled) format.

If your partitions were created in Windows, they are not GUID partitions. You have to delete all of them and create partitions with Mac OS Extended (Journaled) format. Don't forget to click Options button and choose GUID Partition Table! Otherwise, when you install Lion on this partition, you will receive an error message: this partition is not GUID partition.

5. After you have created legal partitions, you can start installing Lion. Just in your snow leopard, double click mac os x lion 10.7 .dmg, In the pop-up window, double click "Install Mac OS X", and then click "Continue". Accept the agreement. You will see this window.

6. Click "Show All Disks..." and choose your external hard drive.

7. Follow the instructions on the screen to complete the installation. You will get Lion installed on your external hard drive. If you want to reboot to the snow leopard, just press Option key on the machine startup.

If you installed Lion on another partition and saved a file on snow leopard partition with AutoSave enabled, you may have error on Time Machine in snow leopard. Refer to this post.

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Testing.