Re: Mentor for a GSoC application wanted (Online ext2/3 filesystem checker)

[Eric Sandeen <sandeen@redhat.com>]

Peter Teoh wrote:
> On Sun, Apr 20, 2008 at 3:07 AM, Eric Sandeen <sandeen@redhat.com> wrote:
>> Theodore Tso wrote:
>>  > On Sat, Apr 19, 2008 at 01:44:51PM +0400, Alexey Zaytsev wrote:
>>  >> If it is a block containing a metadata object fsck has already read,
>>  >> than we already know what kind of object it is (there must be a way
>>  >> to quickly find all cached objects derived from a given block), and
>>  >> can update the cached version. And if fsck has not yet read the
>>  >> block, it can just be ignored, no matter what kind of data it
>>  >> contains. If it contains metadata and fsck is intrested in it, it
>>  >> will read it sooner or later anyway. If it contains file data, why
>>  >> should fsck even care?
>>
>>  It seems to me that what the proposed project really does, in essence,
>>  is a read-only check of a filesystem snapshot.  It's just that the
>>  snapshot is proposed to be constructed in a complex and non-generic (and
>>  maybe impossible) way.
>>
>>  If you really just want to verify a snapshot of the fs at a point in
>>  time, surely there are simpler ways.  If the device is on lvm, there's
>>  already a script floating around to do it in automated fasion.  (I'd
>>  pondered the idea of introducing META_WRITE (to go with META_READ) and
>>  maybe lvm could do a "metadata-only" snapshot to be lighter weight?)
>>
> 
> Can I know where is this script?   Or if u cannot locate it, does it
> have any resemblance to all the stuff mentioned below?.

Google for "lvcheck" and find it buried in a thread "forced fsck
(again?)" on the ext3-users list - I'm not sure if it has an upstream
home anywhere yet...

-Eric