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TOPIC: Doesn't volume optimisation set you up for instant file fragmentation the next time any file...

Doesn't volume optimisation set you up for instant file fragmentation the next time any file... 06 May 2017 20:09 #8212

...increases in size?

Example: Let's say I'm mid-way through a music project when I optimise the drive. All free space is now organised into one contiguous free block - fantastic.

However. Somewhere in the middle of the contiguous used block is my Garageband project, currently sitting at say 1.5GB assuming I'm working with multiple full quality studio recordings of thirty minutes or so.

Now, the next time I do something like slowing down a track or appending something to it, both the .band file and one of the individual AIFFs inside it will increase in size, naturally.

Unless my mac's OS - which I very much doubt given how useless it is at defragging in general - moves the entire file to a new area of contiguous free space on the disk, the file will become instantly fragmented upon saving. And this applies to pretty much any type of file which grows bigger when edited and saved. On that basis, is it necessarily efficient for volume optimisation to essentially crowd all of the used space together, with no room for files to grow without fragmenting, instead of for example defragmenting most of the free space into one block but leaving exceptions for certain file types which due to their nature may need to grow over time?

Just a thought.
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Doesn't volume optimisation set you up for instant file fragmentation the next time any file... 06 May 2017 21:43 #8213

There is no doubt that if you add additional data to a file, it is quite likely to grow in size, and that the new piece (called an extent) will not be contiguous with the rest of the file, resulting in a fragmented file. If the free space is largely not fragmented, and you made a new copy of the file, it is likely that the copy would not be fragmented, because the amount of free, contiguous disk space would be large enough to allow that.

Years ago, at Macworld Expo in Boston (where I met the people who owned Micromat) I went to see the demo of the Be computer. The man who wrote the file system for the BeOS was very pleased when I asked him if it would be possible to add a field to the Open/Save dialog box to specify an amount of free, contiguous disk space to set aside for the file, so that if it never exceeded that size, it would never become fragmented. He said he was working on it. The BeOS survives to an extent, but the Be computer company did not last long, and I do not know if the pre-allocation feature was completed. Fortunately, the man is now working on Apple's APFS file system.

I doubt much effort would be put into pre-allocating space for files to grow without fragmenting now, because so many drives are of the SSD type, which put the file extents in positions that are intended to increase the life of the drive, through wear-leveling. SSDs do not obey disk optimizers.
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Last Edit: 06 May 2017 21:51 by micromattech3.
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