New partition structure?

One of my grand-kids has managed to screw up her laptop again and has returned to the cheapest repairer she knows of to get it sorted out - me.

After getting it working OK I want to add another partition to separate her OS and programs from all her data so that I can take and retain an Acronis image of her C: drive to make my task easier the next time she brings it round - as she surely will. I also want to show her how to back up her data onto removable media.

I know how to do this but the impending task has raised a question in my mind. She has thousands of photos and music tracks on the laptop and is constantly adding new ones and deleting some old ones. Hence her data files must be splattered all over the hard drive intermixed with free space. My question is this - and it is probably a dumb one - when you partition a drive does the new partiton comprise (free space) sectors collected from various tracks and segments of the disk - or are they contiguous.

My guess is that if you started off with an unused disc and created partitions on it - each partition would occupy (and thereafter retain) a continuous physical "chunk" on the disc. Hence all the C: drive items would be butted up together and physically separated from all the D: drive items.

If however you add a partion to a used drive - is the data now all jumbled up physically and only notionally separated into its relevant partition by the MBR.

Defragging a heavily used drive is always a good idea - but is there any merit - in terms of getting data physically into the right area of the drive - in defragging the drive before creating a new partition?

WindowsStar said:

Very good question:

Short answer is that both partitions with have their own MTF and will act as to separate drives, even though they are on one physical drive.

This is a great thing you are doing for her.

Thanks for that - but are you saying that the partitions will be physically jumbled up on the hard drive and not physically in separate areas on the platter - being defined by reference to the address of each file in the MTF.

If I create a new partition - is it correct that the maximum size of the new partition will be the longest contiguous length of free space on the disc and will not include free space from other areas of the disc. If that is the case - defragging the disc before creating the partition would enable a larger partition to be created.

Right or wrong............?

A partition doesnt necessarily hace to be a PHYSICALLY contiguous space. Yes, it can be considered to be LOGICALLY contiguous and indeed that is the way the OS sees it. Similar to a RAID0 setup in which two separate hard drives are seen as one partition. Imagine you have 4 partitions, then delete no. 2 and no. 4, then create a new single partition from the entire free space. How does that happen if partitions were physically contiguous?

Another example, you know the hdd continuosly evaluates sectors in the background (SMART) and marks them bad, if they have become unusable. It then draws in good sectors from a pool of usable spare ones, thus hiding the bad sectors. So again the physically contiguous theory doesnt work- the drive determines where things physically go and keeps track of where everything is.

As for defragging before creating a partition, I'm not sure that will give you more space, since the total free space remains unchanged regardless of defragging. But yes, defrag would create larger PHYSICALLY contiguous chunks, which could theoretically reduce seek time.

Thanks for the explanations - all is now clear....