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jed
08-17-2009, 10:19 AM
Just wondering if it's best to keep all mac volumes to either hfs+ or hfsx if one of the volumes is gong to be a central back-up volume?*

Is there any known issues in backing up from a HFSX volume to a HFS+ one?

Cheers
Jed
*if so which one, hfsx or hfs+? I'm more inclined to go with the former as it's more like *nix. I know it had issues 4+ years back, but it should be fine now.

dnanian
08-17-2009, 10:36 AM
You should generally maintain the same format on the destination as you do on the source, so if you're copying HFSX volumes, do so to an HFSX destination.

jed
08-17-2009, 11:31 AM
Thanks dnanian,

I've been trying to find some detailed apple doco on the pros/cons of both.

All I've been able to find thus far is Technical Note TN1150 (http://developer.apple.com/technotes/tn/tn1150.html#HFSX)
The only other source of info has been silly forum chatter, most of which is highly uninformed & contradictory.

Which would you recommend & why?
The two systems being backed-up are more-or-less general purpose desktops (mac mini's), one is for a very light user.

Let me know if you need to know more first.

curiously,
Jed

dnanian
08-17-2009, 11:46 AM
Well, if what you're trying to say is you want case-sensitive volumes, I strongly recommend against that, especially for a startup volume. But, in most cases, HFSX is the default these days and should be used.

jed
08-17-2009, 11:56 AM
Why do you recommend against HFSX (case-sensitive) for system volumes?

In your 2nd sentence you seem to be suggesting to use it anyway? I'm confused! LOL

Sorry this must be painful for you, but could you please elaborate further?

dnanian
08-17-2009, 12:02 PM
HFSX is not case sensitive. HFSX allows case sensitivity. Big difference.

jed
08-17-2009, 12:31 PM
Why do you recommend against HFSX (allows case-sensitivity) for system volumes?

In your 2nd sentence you seem to be suggesting otherwise I'm confused!
Can you please elaborate further?

dnanian
08-17-2009, 12:53 PM
No, I'm saying that your volume shouldn't be case sensitive. I'm not saying you shouldn't use HFSX.

Case sensitivity can confuse applications that aren't expecting it, since it's not the norm.

jed
08-17-2009, 01:00 PM
But by saying my volume shouldn't be case-sensitive aren't you saying I shouldn't use HFSX, since HFSX "allows" case sensitivity?
Or does HSFX have other inherent qualities which mean I should use it instead of HFS+?

How do I use HFSX but at the same time ensure the volume isn't case-senstive, by being diligent about how I name files/folders?
Sorry for the confusion.....

cheers,
Jed

dnanian
08-17-2009, 01:10 PM
No. I'm saying that you shouldn't turn on case sensitivity, but you should use HSFX. It's something you'd have to turn on when formatted. Don't.

jed
08-17-2009, 01:17 PM
I see, so why use HFSX at all then?

Cheers,
Jed

dnanian
08-17-2009, 01:23 PM
Because it supports other, new things like Journaling, hard links, etc.

jed
08-17-2009, 01:33 PM
Okay I must starting with the wrong understanding of definitions.

I'm realising now.... HFSX is just a generic term for;
HFS+ + new journaling features + case sensitivity....

So when I format the volume you're suggesting I go for HFSX, but HFSX in the sense of: "HFS+ + journaling".
NOT; "HFS+ + journaling + case sensitivity".

Cheers

jed
08-17-2009, 01:49 PM
Doh sorry I forgot my own prior reading! ....

"HFSX volumes are almost identical to HFS Plus volumes (journaled or not), except that they are never surrounded by the HFS Wrapper that is typical of HFS Plus volumes and they optionally support case sensitivity for file and folder names"

So to get HSFX, when I format I choose: "Mac OS Extended (Case-Sentivie, Journaled)"
Then after formatted I just be careful not to enable the "optional" case-sensitivity to individual files & folders?

I'm already on "Mac OS Extended (Journaled)" for most of my volumes, what specifically do I miss out on? (aside from option for case-sensitivity)
Just hard-links?

dnanian
08-17-2009, 02:29 PM
No, just use "Mac OS Extended (Journaled)". DO NOT use Case Sensitive. Everything is basically HFSX these days...

jed
08-18-2009, 12:35 AM
Okay thanks,

The thing that's still got me stumped though is that this article (http://developer.apple.com/technotes/tn/tn1150.html#HFSX) says:
HFSX is an extension to HFS Plus to allow additional features that are incompatible with HFS Plus. The only such feature currently defined is case-sensitive filenames

And yet you just said:
Everything is basically HFSX these days...

Can you explain a little further what you mean?
Is HFSX purely HFS+ + case-sensitivity or is there more to it than that, what is the entire definition of HFSX?

dnanian
08-18-2009, 08:59 AM
The basic problem here, jed, is that the documentation hasn't been updated since 2004 or so, as you can see by looking at the tech note. And I'm not an Apple file system engineer, so I can't provide you with the "entire definition of HFSX".

When it was introduced, HFSX was originally an extension that allowed case sensitivity. But what I've seemed to see since then (i.e. Leopard) is that volumes seem to 'become' HFSX volumes when directory hard links are used on the volume. There may be other things that 'convert' a drive to HFSX -- or at least away from HFS+ -- as well.

It's not a terribly well documented thing, or at least the documentation seems to be partially incomplete. But in the end, the low-level variant of HFS is not something you need to worry about, which -- in addition to the fact that you're dealing with the same documentation I am, and I can only add things that we've seemed to see along the way -- is why I'm being a bit terse in my responses: the lowest level details of the format are generally designed to be transparent to users.

At a high level, SuperDuper! is happy to copy from a case insensitive to a case sensitive volume (if you use Smart Update). If you use erase-then-copy, we always retain the high-level format selected for the source (e.g. Mac OS Extended (Journaled, Case sensitive, etc)). And, while we'll do it, if you copy from a case sensitive to a case insensitive volume two files with the same name in the same folder can overwrite each other.

So, my advice is to ignore the low-level details of HFS+/HFSX, and deal with high level descriptions. Do not format case sensitive unless you absolutely need to (e.g. typically when you're dealing with source code that comes from case sensitive systems and someone used case sensitivity when naming their files [they're non-unique when insensitive]), and even then I'd isolate its use to non-boot volumes to avoid issues with Mac-native applications that aren't compatible with case sensitivity. Any other low-level 'feature' that needs special file system support will get added automatically (or you'll be prompted to turn something non-destructive on by SuperDuper).

jed
08-19-2009, 04:56 AM
When it was introduced, HFSX was originally an extension that allowed case sensitivity. But what I've seemed to see since then (i.e. Leopard) is that volumes seem to 'become' HFSX volumes when directory hard links are used on the volume. There may be other things that 'convert' a drive to HFSX -- or at least away from HFS+ -- as well.

Intriguing so from 10.5.x onwards, even if I choose Mac OS Extended (journaled), Volumes will in time take-on (when hard links are used) attributes that one would associate more with HFSX!

It's not a terribly well documented thing, or at least the documentation seems to be partially incomplete. But in the end, the low-level variant of HFS is not something you need to worry about, which -- in addition to the fact that you're dealing with the same documentation I am, and I can only add things that we've seemed to see along the way -- is why I'm being a bit terse in my responses: the lowest level details of the format are generally designed to be transparent to users.

I suspected this is why you were being so terse, no offense taken!
It's not something that's easy to explain... Particularly since things you've observed are not formal Apple doctrine, & hence leave you vulnerable if you openly assert what you've learned.

At a high level, SuperDuper! is happy to copy from a case insensitive to a case sensitive volume (if you use Smart Update). If you use erase-then-copy, we always retain the high-level format selected for the source (e.g. Mac OS Extended (Journaled, Case sensitive, etc)). And, while we'll do it, if you copy from a case sensitive to a case insensitive volume two files with the same name in the same folder can overwrite each other.

It's re-assuring to know that the app can deal with backups, regardless of the variants used on source/s <---> destination....

So, my advice is to ignore the low-level details of HFS+/HFSX, and deal with high level descriptions. Do not format case sensitive unless you absolutely need to (e.g. typically when you're dealing with source code that comes from case sensitive systems and someone used case sensitivity when naming their files [they're non-unique when insensitive]), and even then I'd isolate its use to non-boot volumes to avoid issues with Mac-native applications that aren't compatible with case sensitivity. Any other low-level 'feature' that needs special file system support will get added automatically (or you'll be prompted to turn something non-destructive on by SuperDuper).

Thanks, for environments like macports etc, I will create an encapsulated volume within the main boot volume that "is" case-sensitive...

jed
08-19-2009, 11:37 PM
Hi Dave,

I know my last responses were mostly statements as opposed to Qns.
But can you please confirm whether or not you agree with them all?

Then I will get out of your hair!

Thanks,
Jed

dnanian
08-20-2009, 08:51 AM
I'm not trying to be a pain, Jed, but I don't know how to respond to your statements. The only one that seems that it might be respond-able is the last one, where you're indicating you're going to create a case sensitive volume to use macports.

What I've said, above, is that you'd only need to do that if you were working with a project that was silly enough to rely on case sensitivity for its filenames. (I think we can all agree that having two files, one named "foo.h" and one named "Foo.h" in a project that do the same basic thing is kind of foolish.)

It's unlikely that any macports projects would do this, at least without warning in the project description. I haven't run into one myself... but if you do run into one, for some reason, you know what to do.

jed
08-20-2009, 02:27 PM
I'm not trying to be a pain, Jed, but I don't know how to respond to your statements. .

So this:

Intriguing so from 10.5.x onwards, even if I choose Mac OS Extended (journaled), Volumes will in time take-on (when hard links are used) attributes that one would associate more with HFSX!

And this:

It's re-assuring to know that the app can deal with backups, regardless of the variants used on source/s <---> destination....

Aren't clear enough? I can re-phrase if you'd prefer, there's no rush!

Cheers,
Jed

dnanian
08-20-2009, 02:29 PM
You seem to restating things I've already said, so I don't understand why you want me to say them again, Jed.

jed
08-20-2009, 02:32 PM
okay thanks for your support/patience.

all the best,
Jed