Some time ago I've partitioned my disk using this scheme: shrinked OS X partition, created NTFS data partition for Windows, then installed Windows on Bootcamp partition.
Recently I installed Parallels Desktop ("run Windows from the Boot Camp partition" mode) which, expectedly, ruined my data NTFS partition: Windows doesn't see it any more, there's just no disk shown under Windows; partition shows as "Unallocated" in Computer Management > Disk Management.
Now I want to split the data partition space between my Bootcamp disk and OS X partition [1], so I have only one partition for Bootcamp and another for OS X.
How can I resize bootcamp partition and OS X partitions without ruining either of them?
After resizing, I would also like to upgrade my OS X from 10.8.5 to latest Mavericks, which sounded impossible with two-Windows-partitions setup.
[1] — as I didn't found a reliable way to have both Windows data partition and regularly update OS X without harming that partition (1, 2).
Best Answer
To share with other users facing a similar situation, here is how I solved the problem--and avoided completely reinstalling OS X and Windows. For reference, my OS X version was Mountain Lion when I started solving the problem--and I needed to upgrade to Mavericks in the end.
This is where you decide how HDD space will be split between OS X and Windows.
The only problem that's left at this point is that Parallels freezes VM when used in "all apps in one window" default mode (which is not Coherence, Fullscreen or Modality mode). Will seek solution for it later; at least it is stable for a week now in Coherence mode.
Before following the above sequence, I tried to recreate data partitition with Windows, converting the unallocated space that sized exactly like the lost partition. Failed: I found that there is a new partition which originally wasn't there: sized 620MB, but it didn't appear as recovery partition among Startup Disks on boot. Didn't try deleting it though, maybe it could help.