MAC Auto Defragment

How much HDD space should be free so the automatic defrag still work. the website suggest that keeping large percentage of HDD free so the auto-defrag works. i'm guessing its 20% is it right?

what is the optimal free space so that auto-defrag and smart file (hot band) placement to work?

edit: will mac auto defragment external hard drive in format other than HFS+ (fat32 etc.)

 

Well, I'm not sure what basis it does the auto format. I think it does it on the fly due to the system being journaled. If I remember correctly, journeled file systems auto defrag themselves based on their designs. Same with journaled tree file systems (such as Reiser's B+Tree system (aweswome linux file system btw)).
If I am incorrect there... then Im really not sure. Maximum performance from the HD is obtained when you have roughly 60% free space I think.
I doubt it will auto defrag external drives.

 

Gotta love on-the-fly defrag.

Quite honestly, when I first heard of Vista, I was looking forward to the 'WinFS' but then they dropped it. Quite sad.

 

but at 60% (really?!?!) free space requirement, the price is too steep! NTFS also support recoverability though (windows name for journaling).

 

actually I hear as long as you have at least 25% free space, you can go at optimal performance, anything more than that the magnetic forces between everything start to interfere with each other and cause a slow down.

 

Yeah, I meant that when you have roughly 60% or higher space left, that is when your drive is the most efficient.

And yes, from what I understand that under 25% or so free space, that the defrag process slows dramatically. I believe Windows wont' let you defrag with less than 20% left.

I don't think journaling in NTFS is the same as auto defrag... if it was their attempt at auto-defrag, it's pretty sad.

 

Journalling is not the same as auto-defrag. OS X HFS+ manages to have a very good performance at keeping the disk unfragmented both by delaying the actual writing and by defragmenting files smaller than 20MB on the fly. I would say that the first resource is way more important, since FS like linux ext2, which isn't even journalled and does not does on the fly defragging, also manages to have vey low fragmentation indexes.
Some good reading:
http://www.kernelthread.com/mac/apme/fragmentation/

 

no no no, what i meant was, journaling is used for data recovery, it keeps log of all files, and windows use that also, with their NTFS. NTFS volumes also fragment slower than FAT32 ones, though i defragment nearly everyday with perfectdisk.

sorry to cause confussion.

 

yeah, i do some researched, and read that, but i don't know how much free space he has.

 

He lists everything under Table1. You might compare both G5 drives. One has about 9GB free(G5 ext) and the other(G5 boot/root) has less than 2GB. The g5 boot drive has a much higher fragmentation (~1750 files vs ~250 files). On the other hand, this might be because their use is different, i.e., a boot drive has more smallish files than an external one. Even then, with 2GB of free space, only about 0,5% of the files are fragmented. It doesn't get much better than that.

 

i still don't get it (sorry), can u explain it a bit more?

so, fragmentation problem occurs at? in windows u can't defragment when u have less than 15% of free space, i use perfectdisk which only require 5% free space. in mac when do this occur?

so machintos do find, eventhough i manipulate large amount of file? the speed penalty is minimal, so it does not matter, correct?

 

Fragmentation doesn't need to be at a certain percent really at all, it can occur whenever, but the more stuff you have on the harddrive the more fragmentation there will be, just think of it that way. You really don't need that much space, but you should have a decent amount.

When I was talking about 25% free space left, I meant that by the time you get to that point, you should start backing things up to a disc (things you dont use as much) because when you start using more than 75% of your harddrive, it starts slowing down, not entirely because of fragmentation, but because of the magnetic forces on the harddrive causes the heads the need for multiple attempts at reading it because of the surrounding magnetic interference.

My macbook is still running as fast as the day I got it, the harddrive is great, even when I only have 12 GB left on my 60GB drive, when it gets that low I clear the drive of things I can afford to have burnt to a DVD. I don't have any third party defrag utility, don't think I ever will becuase OS X does a great job with HFS+ even if the on-the-fly defrag only defrags 20MB and under files, but thats really the important stuff anyways because system files usually aren't that large, they are broken down into separate files and "modules", it's the system/application files that are important.

 

thanks, for the help, that helps a lot!