Scrub free disk blocks

[JD]

  On 08/28/2010 10:24 AM, Patrick O'Callaghan wrote:
> On Sat, 2010-08-28 at 07:42 -0700, JD wrote:
>>> However note that neither of these methods guarantees to scrub
>> indirect
>>> blocks in the filesystem that were used to create the space-filling
>>> files. Maybe they do, maybe they don't, it's not clear.
>>>
>>> poc
>>>
>> Very good.
>> Actually, indirect blocks are used if and only if the file is larger
>> than what can be addressed via direct blocks.
>> So, scrub has no interest in whether or not a file has indirect
>> blocks, nor should it care if blocks are direct or indirect.
>> During file access, the file system will access ANY file block(s)
>> that the process has the right permissions for.
> So what? My point is that after scrubbing and removal of the
> space-filling files, you may be left with a number of sectors that were
> used for indirect blocks during the space-filling phase of the scrub
> process. These sectors may not themselves be scrubbed but will now be
> available on the free list after you're done.
>
> poc
>
You need to study filesystem architecture to gain better understanding.