I have a hard drive with 4 partitions(c,d,e,f) and I want to shrink partition (e) and then extend partition (c) with the shrunk free space. What will happen with the hard drive? Will the Cylinders/sectors be moved??

  • e's free space would be checked and file system would be defragmented if needed. e's file system length would be shortened. e would be moved forward either until it hits f or it makes enough space as requested for c. d would be moved over the same amount. c would extend its file system length would be extended. – jdwolf May 9 '18 at 10:05

Nothing interesting happens physically – the OS just reads data from one place and writes it back to another place.


  1. The filesystem shrinker finds all files which are currently stored outside the planned new boundary and copies their data to a more suitable location.
  2. Once the filesystem reports that the area is free, the whole partition is shrunk by simply adjusting its "end" position.

(Note that most systems don't care at all about physical divisions like cylinders or platters – they work with plain block numbers (LBAs) and let the drive itself figure it out. That way everything works the same with HDDs, SSDs, DVDs...)

  • So only os does the job? LBAs or as we know as sectors won't be changed? Is there any possibility to hard disk failure? Or is it harmful for hard disk? – Jihad May 9 '18 at 6:59
  • As far as the disk knows, it's a completely normal data read/write. (Though if you move partitions, or try to shrink them from the start, then there might be a lot of data to move – but again nothing special hardware-wise.) – user1686 May 9 '18 at 8:29

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