mac and PC defragmenting differences

[Rudyard]

I get an email with computer tips roughly every week and I was reading about defragmenting in one particular newsletter.

It basically went on to say that mac's use a much smarter OS than windows PCs and as such wont need defragmenting (but if you do this is how you do it....)

Which got me thinking, I always thought HDDs got fragmented because as you write and delete data, pockets of empty space are created and files need to be written not in consecutive order but wherever there is room. I figured it was the nature of the beast.

However this email (which in this particular one was very unusually 'mac do it better so you dont need to worry' type rhetoric) is claiming it is the OS that is causing the problem.

How is this so? I appear to have misunderstood what defragmenting is all about.

[redwudz]

While 'some' OS's may do a better job of minimizing fragmentation, it's a fact of any operating system that you move files in and out of the drives will have some fragmentation. Probably the question of how much fragmentation is a problem and how often you should deal with it is more important.

I really don't defrag that often. Maybe once a month at most. I use the Windows defragger. Yes, probably substandard, but I don't seem to have fragmentation problems, even if I don't defrag.

I can tell you, if your Mac is using the NTFS file system, fragmentation problems are likely the same as a MS computer. That is common to all computers, AFAIK.

Does this really matter that much? Not really, IMO.

Fragmentation is most critical to capturing, where, in the worst case, the cap program may have to put a large video files into small spaces created by fragmentation of the drive.

JMO, but I would always capture to a separate drive from my OS boot drive. You can defrag it all you want.

Bottom line, again, IMO. The OS has little or nothing to do with fragmentation. And JMO.

[Dv8ted2]

This is not OS specific. I will give you the technical explanation. Hard drive platters are constantly spinning while the read-write heads are moving back and forth. The data is written to whatever free space as the platter is spinning. The data gets scattered, thus accounting for the need to defragment.

[TJohns]

It certainly IS specific to an OS (actually filesystem). I used to work on a PDP-11 minicomputer OS that could ONLY create contiguous files - it pre-allocated half the largest free block or all the second-largest to any new file and reduced this down to the "real" size when the file was closed.

[Cobra]

It is OS-specific.

If the OS is smart about the way it writes data to the drive, it can minimise fragmentation but for most modern systems it is completely impractical to eliminate fragmentation. MacOS X uses the UNIX Ext2 filesystem, which may be better at minimising fragmentation than NTFS, but I doubt it will go forever without needing a defrag.

[Dv8ted2]

You two are missing my point. I am saying that the hardware creates the need for defragmenting. Regardless of filing system, the defragmenting still has to occur. That is why I said it is not OS specific. This is one of the things that was taught back in A+ classes years ago.

[Cobra]

I didn't say it wasn't hardware-specific. I simply said that the way the OS handles the organisation and writing of data to the hard drive also has a bearing on the rate and degree of fragmentation with the underlying assumption that hard drives will fragment data by their very nature. TJohns also pointed out that there are systems in existence that are able to avoid fragmentation altogether by organising data in a very particular way.

I wonder if the new flash drives would become as fragmented as a standard hard drive or whether they work differently and naturally avoid fragmentation. I'd imagine that they would still become fragmented.

[fritzi93]

No one's mentioned Page File yet. Maybe not terribly important, I dunno. I have an OS drive, plus two separate drives, one used for working with video, and an archive drive. (Also an external for backups). One G of dual-channel RAM. The Page File is on the archive drive, set to 1G, min and max. Task Manager -> Performance indicates Page File usage is never more than half of the allocated amount. Any comments, please educate me. :P

Anyway, I'm with Redwudz, I defrag monthly, and usually Windows Defrag tells me it's not necessary.

[oldandinthe way]

Software algorithms can strongly affect fragmentation.

In the most general sense allocation of memory, disk or computer, can use "first-fit" or "best-fit" algorithms. First-fit uses the first area it can find of adequate size for an allocation unit, therefore it runs faster but may increase fragmentation. Best-fit allocates to the smallest area which meets all the storage needs and causes less fragmentation, typically runs slower but fragments less.

There are variations between these extremes.

Could the Mac and Windows use different algorithms - of course. But differing versions of Windows have used different algorithms as well.

Hard Disks, Flash Drvies - any hardware which has read/write access and a file system will fragment. Its a function of software.

[oldandinthe way]

The Page File is on the archive drive, set to 1G, min and max. Task Manager -> Performance indicates Page File usage is never more than half of the allocated amount. Any comments, please educate me. :P

If you never use more than half of the pagefile, it is twice as big as it need be. If you aren't suffering from lack of space, I'd leave it alone.