Partitioning my Hard Drive

[yellow]

For many filesystems (ext2, HFS+, UFS, etc) the block size can be specified when the disk is formatted.

Where? Out of curiosity...

 

[mrichmon]

Where? Out of curiosity...

You cannot specify the block size in any of the GUI tools, you have to drop to the command line. Disk Utility is just a GUI front end to a bunch of command line tools for the most part.

When you format a file system using Disk Utility the actual formating is performed by the command line tool "newfs_hfs". This tool has a "-b" option to specify the block size. Apparently the default block size is 4KB for this tool. On my systems the HFS file systems have a block size of 512B, so presumably Disk Utility calls the newfs_hfs tool using the -b option to set the smaller block size.

 

[yellow]

You cannot specify the block size in any of the GUI tools, you have to drop to the command line. Disk Utility is just a GUI front end to a bunch of command line tools for the most part.

Really? I had no idea.

I'm not looking in GUI tools. And there it is.. -b flag.
Funny that apropos didn't catch that, guess it's not in the database because there's no man page..

And now to test that option to change the block size on a disk..

 

[mrichmon]

Really? I had no idea.

I'm not looking in GUI tools. And there it is.. -b flag. Funny that apropos didn't catch that, guess it's not in the database because there's no man page..

man newfs
man newfs_hfs

Brings up the pages on my PPC and Intel systems.

Make sure that you have your MANPATH set correctly to include the /usr/share/man folder.

 

[yellow]

typo'd.. well even stranger that apropos didn't come up with it. ANYWAY...

Odd. Having troubles with it.. despite me specifying a block size, it's defaulting to 4k.

yellow% sudo newfs_hfs -h -b 1024 -v TESTDISK /dev/disk2s3
Initialized /dev/rdisk2s3 as a 114345 MB HFS volume
yellow% sudo newfs_hfs -N -v TESTDISK /dev/disk2s3
234179424 sectors (512 bytes per sector)
HFS Plus format parameters:
        volume name: "TESTDISK"
        block-size: 4096
        total blocks: 29272428
        first free catalog node id: 16
        catalog b-tree node size: 8192
        initial catalog file size: 26214400
        extents b-tree node size: 4096
        initial extents file size: 7340032
        initial allocation file size: 3661824 (894 blocks)
        data fork clump size: 65536
        resource fork clump size: 65536

I'm doing something wrong. I'll have to worry about it tomorrow.

Thanks for the lesson!

 

[mrichmon]

You cannot specify the block size in any of the GUI tools, you have to drop to the command line. Disk Utility is just a GUI front end to a bunch of command line tools for the most part.

Correction: Disk Utility is a GUI front end that calls to the command line tool "diskutil" for most disk operations. For creating and manipulating disk images Disk Utility calls to the command line tool "hdiutil".

I assume that diskutil calls to newfs to do the actual filesystem creation.