Filesystem Features?

F

Flipsidejones

Registered
Hey..

I am coming to OS X from BeOS, which had a filesystem that did all sorts of nifty tricks. So does Win2k/XP.

My question is about the OS X file system. I would research it myself, but the powerbook has yet to ship. :-(

Anyway, what featuers does OS X have in its file system? Encryption? File Locking? Quotas? Attributes?

Is the file system journaled, or does it need to scan for errors if it isnt shut down properly?

Anyway... any info would be nice. :)
 
It depends on which filesystem u want to use with OS X.
Standard is Apple HFS+
It needs to be checked for errors everytime the system ain't shutdown properly. Anyways, OS X never crashed on my system yet :)
HFS+ Supports long filenames (up to 255 characters i think) and supports all the file attributes that r also supported by windows (protected, hidden etc..). It also supports file resources, as used under OS 9 and below. OS X also allows to set user privileges for every single file on ur hd. Unfortunately OS 9 does not recognize those privileges, so its only secure under OS X [yet].

File encryption is not yet built into OS X, but theres an encryption utility on the OS 9 installer CD which can also be used with OS X. :)
 
I'm pretty sure OS X doesn't have any journaled file systems yet. Don't know what A/UX used.

-Rob
 
Just to clear up a few misconceptions you have about UFS.

The equivalent to a file alias on UFS is not a symbolic link, but a hard link (directory aliases must use sym-links). Instead of doing 'ln -s src alias', you would do 'ln src alias'. This uses the actual inode on disk to reference the file, as well as survives moving the file (so long as it is on the same file system).

UFS is case sensitive, something that HFS is not.

UFS stores the immutable flag in the inode of the file itself. Also, immutable is honored by root as well, and the only way to undo immutable is to boot into single-user mode and remove the flag. This is for security reasons, as you don't want certain files be to able to be changed when in multi-user mode. Most unices don't use this often, but on a firewall this flag is vital.

In OS X, the extension is the file association mechanism. If you don't want IE to open HTML files, but rather Netscape, you change the assocation (I believe OS X is using mime-types for this).
 
Originally posted by Flipsidejones
Hey..

I am coming to OS X from BeOS, which had a filesystem that did all sorts of nifty tricks. So does Win2k/XP.

My question is about the OS X file system. I would research it myself, but the powerbook has yet to ship. :-(

Anyway, what featuers does OS X have in its file system? Encryption? File Locking? Quotas? Attributes?

Is the file system journaled, or does it need to scan for errors if it isnt shut down properly?

Anyway... any info would be nice. :)
Click to expand...

my file system can stand on it's hands; balance books on its nose, whistle a happy tune and recite the Gettysburg address backwards... all at the same time.!!!!!

if there is something that windows or BeOS does (or did!) that you thought was really nifty... just look around on the net for the source files to the original code which they RIPPED-OFF and implement it in the unix layer.

the file system is controlled by the OS and the software which it supports. The file system has all the basic capabilities which anyone could require. You are in command...encrypt you entire disk so your mom can't find the porno... you can install whatever you want and if it is really nifty... start a software company and take over the planet....
 
OK, then maybe I don't understand aliases that well. Please tell me what would happen in the following situation (I can't test this as I don't have 3 macs to do it).

Mac1 mounts volume1 and volume2 (different physical volumes) from Mac3 and creates an alias on the desktop to a file on volume1. Mac1 then shuts down.

Mac2 boots up, and moves (not copies and deletes) the file from volume1 to a volume2.

Mac1 then boots back up, and tries to use the alias. Will it work?

If this will work, then I had a fundemental misunderstanding of aliases WRT files, and I am pretty impressed. WRT directory aliases, unix has nothing that could maintain the state with any kind of move (you could, if you were the crazy type, edit the filesystem and create another directory entry pointing to the same inode, but that could cause real problems).

As for the file associations, I appolozie. The way you wrote it, it looked as though you were talking about all .html files, not a particular .html file.
 
testuser:
One of these days I'll have to get a hold of a few macs to check out if the alias works in that case. :) Curiousity will eventually kill me, I'm sure.

WRT the encrypted file system, W2k/XP does a pretty decent job with this. To do it, a user has a certificate in their local certificate store, and the OS uses this to encrypt the file. It also encrypts to an alternate encryption key which the recovery agent can use (EFS isn't really secure unless you export and remove the recovery agent's ADK). To do the actual encryption, Windows generates a symmetric key to use for a given file (1 file per key), and encrypts the key with the user's key and the ADK. The key is then stored in the NTFS metadata. In the NTFS directory, a flag is set marking the file as encrypted, and the contents are encrypted with the symmetric key. Whenever the user tries to access the file, the OS decrypts the file as part of the fread, leaving the file encrypted on disk.

Overall they did a pretty decent job with it. The only 2 problems are the requirement to export and remove the ADK from the recovery agent, and trying to manage it in an enterprise environment with thousands of users.
 
You must log in or register to reply here.
Back
Top