htfsdebug
You can download "htfsdebug" from Amit Singh's "Mac OS X Internals" site.. It's a tool that will examine your HFS+ filesystems and report various statistics. Although presented as a "debugger", it's really not: this is strictly read-only. However, it can provide a lot of useful and interesting information.
For example, here is it's "summary" output. By specifying "-t 10", I asked it to only list the ten largest files it found on my disk:
$ sudo hfsdebug -s -t 10 Password: # Volume Summary Information files = 526923 folders = 102959 aliases = 0 hard links = 5552 symbolic links = 32556 invisible files = 222 empty files = 8062 # Data Forks non-zero data forks = 518689 fragmented data forks = 1335 allocation blocks used = 17195327 allocated storage = 70432059392 bytes (68781308.00 KB/67169.25 MB/65.59 GB) actual usage = 69052849691 bytes (67434423.53 KB/65853.93 MB/64.31 GB) total extent records = 521165 total extent descriptors = 541078 overflow extent records = 2476 overflow extent descriptors = 19519 # Resource Forks non-zero resource forks = 1068 fragmented resource forks = 2 allocation blocks used = 15638 allocated storage = 64053248 bytes (62552.00 KB/61.09 MB/0.06 GB) actual usage = 60915072 bytes (59487.38 KB/58.09 MB/0.06 GB) total extent records = 1068 total extent descriptors = 1071 overflow extent records = 0 overflow extent descriptors = 0 896 files have content in both their data and resource forks. # Largest Files (data forks) on the Volume # Using 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB rank size cnid path 1 7.40 GB 9079398 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{5fbaabe3-6958-40ff-92a7-860e329aab41}.hds 2 4.79 GB 6254336 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{5e74b8f6-c1ea-432d-8227-4a33b2cf8447}.hds 3 2.99 GB 8659761 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{3887679c-52c3-4dc7-9199-a4240cf61062}.hds 4 2.97 GB 10390184 Macintosh HD:/Users/apl/Documents/Virtual Machines/ Ubuntu.vmwarevm/Ubuntu.vmdk 5 2.43 GB 6265728 Macintosh HD:/Desktop/vmware/vmware/SCO/SCO.vmdk 6 2.37 GB 6524650 Macintosh HD:/Users/apl/Library/Parallels/ Ubuntu/lin26.hdd/lin26.hdd.0.{5fbaabe3-6958-40ff-92a7-860e329aab41}.hds 7 2.00 GB 9446500 Macintosh HD:/private/var/vm/sleepimage 8 1.83 GB 8655591 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{aa7d9a8c-9391-4324-b35e-12255889da67}.hds 9 1.16 GB 6267051 Macintosh HD:/Desktop/vmware/vmware/SCO507/SCO507.vmdk 10 1024.00 MB 10979700 Macintosh HD:/private/var/vm/swapfile5
I probably could have guessed that VMware and Parallels images would be my biggest files, and I wasn't surprised to see a swapfile mixed in, but what is that /private/var/vm/sleepimage? Well, actually that's something I don't need now because I use RAM Sleep Mode, so I could save myself a bit of space by removing it (and I did).
This can also show fragmentation, though Amit says HFS+ defrags on the fly anyway and does other things that make fragmentation a non-issue. Tallying up fragmented files can take quite a while to run, but does give a summary at the end:
# Top 5 Files with the Most Extents on the Volume rank extents blk/extents cnid path 1 10497 4.17 10480743 Macintosh HD:/private/var/log/system.log 2 2025 957.97 9079398 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{5fbaabe3-6958-40ff-92a7-860e329aab41}.hds 3 1255 623.78 8659761 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{3887679c-52c3-4dc7-9199-a4240cf61062}.hds 4 819 1533.34 6254336 Macintosh HD:/Users/apl/Library/Parallels/Microsoft Windows XP ie6/winxp.hdd/winxp.hdd.0.{5e74b8f6-c1ea-432d-8227-4a33b2cf8447}.hds 5 679 1145.24 10390184 Macintosh HD:/Users/apl/Documents/Virtual Machines/ Ubuntu.vmwarevm/Ubuntu.vmdk Out of 518680 non-zero data forks total, 517346 (99.74 %) have no fragmentation. Out of 1068 non-zero resource forks total, 1066 (99.81 %) have no fragmentation.
So that looks pretty good, doesn't it? By the way, Amit has a number of very interesting articles at OSX Book Bonus Content and I do recommend his excellent Mac OS X Internals Book also.
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