Windows 10: Why is partition merging so slow? (Not specifically a Win10 question)

  1.    12 Nov 2017 #1

    Why is partition merging so slow? (Not specifically a Win10 question)


    Hello,

    I know this isn't a question that is specific to windows 10, it's just I'm facing it, again, while using windows 10, haha.

    Simply: would someone know why it takes so goddamn long to merge together the partitions of a hard disk drive?

    I tried to google for an explanation, but all I found were pleas for help after failed mergings, or companies trying to recommend their own brand for the operation, or else the wikipedia article for merging data in database situations - not what I'm seeking, thus.
    But I must also reckon my google-fu sucks, I usually fail to find the proper wording that will yield good results.

    I don't beg for a complete explanation right here right now, if you can find a link to a page with the explanation, that will be perfect :)

    *

    The reason I'm asking after all these years, if you wonder.

    In my current case, merging a 955 GB partition with a 450 GB partition, my program (easeus partition master free) has been at it for over two hours, and from the looks of it I'm good for double that before it's done.
    The disk usage (as noted by the windows tasks manager) has been between 60 and 80 MB/s since the beginning of the operation. It matches: at max disk speed, it would take around 4 hours to move the totality of the data in the largest partition.

    So it's not a nightmare, it really seems the program has to move every single byte for some reason to proceed to a merging between partitions.
    In my - clearly wrong - imagination, it should - no, it ought to - be done in a jiffy, just by updating the MFT, telling the system "look, you see that file? Now, you will find it here. Moving on. Look, you see that file? Now, you will find it here. And so on."
    While, here, we're at max disk reading speed for hours, apparently data really has to be physically moved, isn't it insane?!? There must be a reason it can't be made in a faster and more efficient manner than that, and I'm extremly curious to learn it.

    Thanks to whoever manages to find a link to an explanation, that will make my day :)
      My ComputerSystem Spec

  2.    12 Nov 2017 #2

    Welcome to the forum the maths behind this is herendous you have to calculate the files size start and stop then work out were its going to fit move it alter partition and repeat maybe 1,00 times
      My ComputerSystem Spec

  3.    12 Nov 2017 #3

    Samuria said: View Post
    Welcome to the forum the maths behind this is herendous you have to calculate the files size start and stop then work out were its going to fit move it alter partition and repeat maybe 1,00 times
    Thanks, Samuria!

    TBH I already suspected something filthy in terms of computering was going on, yeah. But would you have more info, precisely? Or even the proper keywords to find explanations in a search engine?

    I don't pretend I'll come up with a better way of knowing, it's just I'm eager to at least understand why it's going so badly. A bit like a mechanic, I like to understand what's happening below the hood =)
      My ComputerSystem Spec

  4.    13 Nov 2017 #4

    Basically, there are many steps that have to be taken during such job. The exact way varies from program to program used but.... Partitions are optimized first so all data is in a continuous block, more data on it, longer it takes. After that, data is moved practically twice, first backed up and than written to other partition while at same time moving around FAT and writing new data addresses to it. Needless to say that heads in a HDD are going nuts at that faze and it's good workout a HDD goes thru. With a slow HDD and a lot of data it's not exceptional to spend hours in doing it.
      My ComputersSystem Spec

  5.    13 Nov 2017 #5

    CountMike said: View Post
    Basically, there are many steps that have to be taken during such job. The exact way varies from program to program used but.... Partitions are optimized first so all data is in a continuous block, more data on it, longer it takes. After that, data is moved practically twice, first backed up and than written to other partition while at same time moving around FAT and writing new data addresses to it. Needless to say that heads in a HDD are going nuts at that faze and it's good workout a HDD goes thru. With a slow HDD and a lot of data it's not exceptional to spend hours in doing it.
    Yeah partitions are laid out so as best as possible data is contiguous. Just changing pointers to new drives should work but hard drive would be shunting back and forth further than is needed. It make sense to translocate all data as close as possible. Not only that but without tidying up data, in time it will probably lead to more excessive file fragmentation.

    Not sure if this would be important with SSDs though.
      My ComputerSystem Spec

  6.    13 Nov 2017 #6

    Yes, SSDs don't care about places data is stored at but other processes would come into play, like GC (Garbage Collection) to empty out "deleted" data. There's also space, even whole partition reserved for "Overprivisioning" used mostly for load leveling so that part also has to be taken into account.
      My ComputersSystem Spec

  7.    13 Nov 2017 #7

    CountMike said: View Post
    Yes, SSDs don't care about places data is stored at but other processes would come into play, like GC (Garbage Collection) to empty out "deleted" data. There's also space, even whole partition reserved for "Overprivisioning" used mostly for load leveling so that part also has to be taken into account.
    Blimey "garbage collection" is a blast from the dim and distant past

    http://www.atarimagazines.com/comput..._Computers.php
      My ComputerSystem Spec

  8.    13 Nov 2017 #8

    cereberus said: View Post
    Blimey "garbage collection" is a blast from the dim and distant past

    http://www.atarimagazines.com/comput..._Computers.php
    Words get recycled a lot changing the meaning along the way.
      My ComputersSystem Spec

  9.    13 Nov 2017 #9

    CountMike said: View Post
    Words get recycled a lot changing the meaning along the way.
    Especially by our friends across the Pond .
      My ComputerSystem Spec


 

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