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Re: Resize2fs Questions




> On 31 Jan 2022, at 23:36, Andy Smith <andy@strugglers.net> wrote:
> Hello,
> 
> On Mon, Jan 31, 2022 at 05:57:45PM +0000, Gareth Evans wrote:
>>> On 31 Jan 2022, at 17:37, Andy Smith <andy@strugglers.net> wrote:
>> Hi Andy, I appreciate the data doesn't go anywhere, but...
>> 
>>>> then I delete P2 and then add a
>>>> new partition which defaults to 2.
>> 
>> doesn't that at least result in the appearance of deletion (an empty partition) if done after the resizing?
> 
> A partition table is just basically a list of start and end
> positions of partitions.
> 
> When you "delete a partition" all you've done is removed the entry
> in the table, but the data that belongs to the partition you just
> deleted is still on the disk in the place where it always was.
> 
> If you then put back a partition the same as it was before (or
> bigger), it will then show up as a valid partition again.
> 
> In the case of a grow, you then tell your FS or whatever to use the
> empty space that's now at the end.
> 
> In the case of a shrink, you already told your FS (or whatever) to
> create a gap between the end of the FS and the end of the partition,
> so after deleting that partition you can add a "new" partition that
> has an end position that matches the end of the shrunken FS.
> 
> If this does not make it clear that "deleting a partition" in fdisk
> or parted or whatever is a perfectly normal thing to do that doesn't
> in itself trash your data, I don't know how better to explain it and
> you will have to elaborate as to where the confusion lies. I don't
> know what "the appearance of deletion" means to you in this context
> or why you think it harms any data that is on a disk.

Hi Andy,

I'm afraid I replied before I'd thought through what I had in mind, which was, wrongly, that deleting a partition unlinks the files it contains.

"Appearance of deletion" was a poor choice of words.  I meant that unlinked files could be recovered (if not first overwritten), although deletion is indeed the appropriate term.

Thinking of testdisk/photorec reminded me that I was thinking (and writing) wrongly in the first place.

Thanks anyway for your explanation.

Gareth
 
> 
> Cheers,
> Andy
> 
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