Re: resize + cp -> wrong size + request for help

[Andrew Clausen]

On Thu, Nov 29, 2001 at 11:50:37AM -0800, Ross Boylan wrote:
> 1) This seems like a bug.  It may be significant that /hdc6 showed as
> ext3 on one diagnostic before I did anything.  Also, I ran e2fsck in
> the middle of things--maybe it fixed the wrong size?

The problem is you didn't quit parted before using other tools to look
at the file system.  The buffer cache for /dev/hdc and /dev/hdc6
were out of sync, so you had some buffers that were "old", and some
"new".

> 2) What's the best way to fix this?

In the next stable branch of Parted (i.e. 1.6.x), Parted will flush
the caches after every "dangerous" operation.

> 3) Is there any way to recover the contents of /hdc6 before the cp?

No.  The ext2 cp does a raw block copy, that basically obliterates
everything :(

> 4) Consider changing the name of the cp command to replace or
> something similar.  I thought it was going to add to the files that
> were already on the partition, not replace them.  Though the behavior
> is documented in the manual (too bad I didn't read it!) it is
> unexpected behavior for cp.

I disagree.  If you do "cp /etc/fstab /etc/mtab", you expect to
lose /etc/mtab, right?  You only get the "add" behaviour for
directories.  /dev/hda5 is a device (i.e. a file, a single linear
address space), not a directory.

> 5) I'm not sure what would have happened if I specified a different
> start than the existing one (given the warning parted can't move the
> start) or an end past the legal reason.  I hope that's safe.

It's safe.  Parted (is designed to... no legal guarantee) to never
do something "stupid", like obliterate a file system.  It has
a constraint solver, heaps of sanity checks, warnings, etc.

> Megabytes are not natural units for this problem, and it would be nice
> to add the ability to specify postion by other means (cylinder, CHS,
> sector) and also to have a separate command extend that only moves the
> end.

I intend to add support for other units.  CHS is completely unnatural.
It isn't even well-defined.  Perhaps gigabytes would be more appropriate
nowadays?

> Also, some default behavior to fill available space would be
> nice.  I know it's easier to wish for these things than do them :)

That's too high-level.  Should be part of another tool (that uses libparted)
IMHO.

OTOH, 1.5.x (unstable) introduces a default interface.  I.e. if you
don't supply enough parameters, it will ask you for them, and will
offer you a default choice.  That default could be "the maximum",
and you get your desired behaviour for free ;)

Andrew