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MacBytes
Nov 8, 2007, 09:56 AM
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Category: Mac OS X
Link: Apple tries to stem Time Machine complaints (http://www.macbytes.com/link.php?sid=20071108105610)
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Posted on MacBytes.com (http://www.macbytes.com)
Approved by Mudbug

lshaner
Nov 8, 2007, 10:43 AM
http://www.macbytes.com/images/bytessig.gif (http://www.macbytes.com)

Category: Mac OS X
Link: Apple tries to stem Time Machine complaints (http://www.macbytes.com/link.php?sid=20071108105610)
Description:: none

Posted on MacBytes.com (http://www.macbytes.com)
Approved by Mudbug

The article says nothing of the design flaw which prevents Time Machine from working on a per-file basis against File Vaulted volumes. Anyone who uses File Vault for their home directory and DOES Not make regular backups of the sparse file is sitting on a time bomb of one day losing their entire home dir. According to Apple technical support representatives, should corruption occur in the File Vault sparse image, due to bug or disk error, there is a strong likelihood that the entire contents would be lost.

So when using File Vault, a regular and consistent backup solution is imperative. Prior to Time Machine, the most reliable method of backing up the sparse image was to log out of the File Vaulted account and log back into a different admin-enabled acccount and back up the entire boot drive + /Users volumes or at a minimum, just back up the file-vault sparse images.

Prior to release of Leopard, there was much hope that Time Machine would work seamlessly with File Vault and allow for a less cumbersome backup mechanism.

Unfortunately, Time Machine is still only operates on the entire sparse image file, so it will only back up the entire "blob" when you log out of a File Vaulted account. It's really no better than the pre-Leopard way of doing things. Yes, more automated, but not really any more effective than the method described using a separate admin account.

The lack of integrated File Vault + Time Vault was the biggest disappointment for me re: Leopard. I was *sooo* looking forward to a more effective way to back up my File Vaulted home-dir. No joy for me.

As it stands, I have elected to turn off File Vault when I'm going to be home for more than a few days. Then I turn File Vault back on before I head on the road. It takes 45 minutes in each direction to decrypt / encrypt my home-dir. I just hate the waste of time and I really feel that there's a possiblity that exercising File Vault in this way is actually increasing my chances of corruption. :-(

Yeah, Apple needs to address this and implement a transparent Time Machine + File Vault integration-- on a per-file basis, rather than the current, disappointing, "entire blob" implementation.

Just one more reason that Time Machine doesn't quite meet expectations.

waldo1979
Apr 25, 2008, 02:42 PM
The article says nothing of the design flaw which prevents Time Machine from working on a per-file basis against File Vaulted volumes. Anyone who uses File Vault for their home directory and DOES Not make regular backups of the sparse file is sitting on a time bomb of one day losing their entire home dir. According to Apple technical support representatives, should corruption occur in the File Vault sparse image, due to bug or disk error, there is a strong likelihood that the entire contents would be lost.

So when using File Vault, a regular and consistent backup solution is imperative. Prior to Time Machine, the most reliable method of backing up the sparse image was to log out of the File Vaulted account and log back into a different admin-enabled acccount and back up the entire boot drive + /Users volumes or at a minimum, just back up the file-vault sparse images.

Prior to release of Leopard, there was much hope that Time Machine would work seamlessly with File Vault and allow for a less cumbersome backup mechanism.

Unfortunately, Time Machine is still only operates on the entire sparse image file, so it will only back up the entire "blob" when you log out of a File Vaulted account. It's really no better than the pre-Leopard way of doing things. Yes, more automated, but not really any more effective than the method described using a separate admin account.

The lack of integrated File Vault + Time Vault was the biggest disappointment for me re: Leopard. I was *sooo* looking forward to a more effective way to back up my File Vaulted home-dir. No joy for me.

As it stands, I have elected to turn off File Vault when I'm going to be home for more than a few days. Then I turn File Vault back on before I head on the road. It takes 45 minutes in each direction to decrypt / encrypt my home-dir. I just hate the waste of time and I really feel that there's a possiblity that exercising File Vault in this way is actually increasing my chances of corruption. :-(

Yeah, Apple needs to address this and implement a transparent Time Machine + File Vault integration-- on a per-file basis, rather than the current, disappointing, "entire blob" implementation.

Just one more reason that Time Machine doesn't quite meet expectations.

There appears to be a lot of confusion in this realm, so let me add some clarity.

Leopard introduce the concept of a sparse bundle image. In a bundle the image is “banded” into small 8mB files. This allows the sparse image to be backed up only changes and not the whole image every time. More information about this can be found here:
http://macosx.com/article/live-filevaultsparse-bundle-backups-in-leopard.html

There still exists a problem however. Time machine will not backup your sparse disk image (file vault home directory) if it’s mounted.
http://www.radiotope.com/content/os-105-time-machine-and-file-vault

One last obstacle… how do you get Time Machine to deal with backing up large files like VMWare images? When you create a vmware image you can tell the install to use 2gB files, which helps, but doesn’t solve the issue. People who do video editing are just screwed.

In the long run Apple could solve this issue using a ZFS filesystem (which does true journaling), therefore allowing for the writing of only data deltas.

-Rob

twoodcc
Apr 25, 2008, 04:11 PM
well, time machine is nowhere near perfect in my mind, but it does seem to work for me.

i even have 5 external drives in a RAID (not redundant), and it works.

Dimwhit
Apr 25, 2008, 05:01 PM
Anyone who uses File Vault for their home directory and DOES Not make regular backups of the sparse file is sitting on a time bomb of one day losing their entire home dir.

I would hope that anyone using File Vault and not able to properly use TM for backup would instead/also clone their drive on a regular basis, thus eliminating the risk of losing their entire home dir.

As for me, I love TM. But I don't use File Vault and I haven't run across any issues with it, at least as far as I use it.