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Measuring Fragmentation in HFS+
keyblob8K writes "Amit Singh takes a look at fragmentation in HFS+. The author provides numbers from his experiments on several HFS+ disks, and more interestingly he also provides the program he developed for this purpose. From his own limited testing, Apple's filesystem seems pretty solid in the fragmentation avoidance department. I gave hfsdebug a whirl on my 8-month-old iMac and the disk seems to be in good shape. I don't have much idea about ext2/3 or reiser, but I know that my NTFS disks are way more fragmented than this after similar amount of use."
but I know that my NTFS disks are way more fragmented than this after similar amount of use
Is this based off of instinct, actual data, or what?
Agreed and the fragmentation on NTFS can have subtle effects (such as fragmenting the MFT) that are NOT easily fixed by simply running a defragmentation tool.
The main problem with fragmentation is cache-faults. The disk drives assume that you will be reading the following sector;: when you don't, you'll have to wait for the sector you requested to be brought in from disk. This applies even in the face of the tricks you mention.
Religion is regarded by the common people as true, by the wise as false, and by rulers as useful.
A lot of people simply equate disk fragmentation with slow application execution and opening of data files. While this is the most visible effect that fragmentation has on a system, it's not the only one. If you are dealing with large files (multi track audio, video, databases) then you will get a different kind of performance hit due to the non-contiguous nature of the free space you are writing to. If you want to capture video with no dropouts, you really want a drive that has all of it's free space basically in one location. This allows you to write those large files with no physical disruption in location. Please do not think that the only benefit to unfragmented space is just "my programs launch faster". If you do any real kind of work on your system with large data files, you should know that a defragmented drive is a godsend.
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This is a very arcane procedure in XP. I shall try to explain, but only a professional should attempt this.
1. Right click on drive icon, select properties
2. Select Tools tab and click on "Defragment Now"
3. Click on "Analyze"
4. When analysis finishes, click on "View Report"
This shows two list windows, one containing general properties of the disk such as volume size, free space, total fragmentation, file fragmentation and free space fragmentation. The second list shows all fragmented files and how badly they are fragmented.
If you're not using the same tool to measure fragmentation on each OS, how do you know that they're using the same semantics to decide what a fragmented file is?
IIRC, the Linux tools use a different metric to calculate fragmentation than the NT ones.
Coming soon - pyrogyra
Are you talking about the "Optimizing System" phase? As far as I know, that updates binary-library prebindings--not fragmentation. You can read more about it here:
m an ce/Conceptual/LaunchTime/Tasks/Prebinding.html
http://developer.apple.com/documentation/Perfor
In theory, when you install anything (on any system) and have a reasonable amount of contiguous free space on your disk, the installed files should always be unfragmented since I believe that's what most file systems look for first to allocate: a large chunk of contiguous space.
Fragmentation typically occurs more when you open a file, increase its size, and write it back out. But operations that write large files to disk that do not know beforehand what the final size may also do this to some files that were only written once to your disk. For example, some of the largest fragmented files on my HFS+ volume are things snagged with BitTorrent. The fragments in these files are very regular chunks of blocks, which could be the typical 'buffer' size BT grabs when writing.
That isn't a filesystem that is a tape. Any number of tape systems exist, pick whichever one you like.
Last time I checked filesystems were also operatining system components. Often these components might be referred to as drivers.
Then you didn't check hard. Again, HFS+ is a specification of how to write data to media in order to organize another collection of data. The implementation is what handles the defragging. There are no drivers involved as drivers are the software component of a hardware/software union and there is no hardware involved at this level (just logical organization).
No, it's just that the defragger built-in to Win2K/XP is shite. Its runs like molasses in liquid helium, and it almost never does a complete job in a single run. You have to run it several times in a row before it's even close to doing a reasonable job. And if it's your system drive, then there are some files (including the swap file) that it simply won't touch no matter how badly the blocks are scattered. This can be a real pain in the posterior if you're trying to defrag a drive in preparation for a Linux install.
Schwab
Editor, A1-AAA AmeriCaptions
A word about browsers (and any thing else that requires change):
People, in general (more than 50% of them), prefer to resist change, and for that matter, extra work and/or thinking. It's just the way they are. It's what explains product loyalty. In this case, the product loyalty is browser based.
In my job, as a web server support admin, I find that 95%, or more, of the people I speak with in support situations are not even aware of the alternatives available to them. In fact, just last Sunday, a friend of mine was showing off his new Power Book to me (by the way, even though I am a complete Linux advocate, you have to give credit where credit is due: Mac has a great GUI). I had to laugh during his enthusiastic demo of Mac OS X's features when my friend opens up Safari and goes, "Check this out. It's a feature called 'tabbed browsing.'" He was a kid in a candy store and had just found new, profound flavor of buble-gum or something. But, how could I not laugh at this previously 100% Windows user's intron to me of something that I began using in Opera, back around 5.x-6.x (I really don't remember if 5.x had tabs or not. I really don't care since that browser drives me crazy. But that's just me.) Translation: it's be around for years. In my work day I begin with 12-13 of them opening in FireFOx (NT 2000 doesn't like that, even with 512MB RAM, but it gets by well enough). The number of tabs only increase from there, unless there's an accident of closing a tab. But no big deal there either, I just open another one and then drag it back between where I normally would have it in my list of tabs. You won't find any thing like that in a browser direct from MS.
Another example: my co-workers, particularly the NT techs. Most, certainly not all (thank God), of our NT techs still use IE for their work. I don't really know what they need for their work, but I've seen their desktops and their taskbars; WHAT A MESS! It's beyond me why they would waste their time with a browser (read: IE) that doesn't organize their open web pages into one taskbar entity, because they DO use other programs on the NT 2000 desktop, which we all must use at my job, regardless of the servers we admin for. (If you haven't guessed yet, I don't admin for NT servers, I get the please and ease of admining for Linux boxes. And a big THANK GOD for that!)
Back to my point: most people are not aware of features in other browsers AND if they are aware of new inovations (read: tab browsing, which is one reason I will never go back to IE) they are not in any hurry to change and think and evaluate something that, however troubling it can be at times: pop-ups, vulnerbilities, "________________" [fill in the blank], lack of inovation, etc.
So what if most of /. visitors are Windows based? There are plenty of better choices to MS products, even on their own OS platform. But, people the world over resist change; they get stuck in a rut, good or bad in it's results, and they either don't like to change, don't "need" to change, or cannot change. Thus, the end result is resistance to change; for the better or for the worst.