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Re: Reg: Porting UFS/VxFs to ext2 (fwd)



Ha. I just have the same idea of doing it in place and then I saw
your email.

I will recommend using the backup and store giving the risk of
make it wrong somewhere.

However if you have to do it in place, assume there is enough
free space on your convert partition:

1) port e2fsprogs to your native system which using the UFS.
   e2fsprogs has cross-platform in mind. Hopefully you can
   just ./configure and make.

2) Create a large sparse file on your system, same size as your
   convert partition.

3) run mke2fs on that file.

4) use debugfs, write command to move file one by one from your
   native system to the image file.

   We can do so smart trick if there is some file
   in the convert partition is very big, i.e. large than half
   of the partition size. We can copy from the tail and ftruncate
   the original file piece by piece.

5) When this is done. You have only one large ext2 image file in the
   partition. You only need to relocate the block to raw partition.
   Be careful the mapping of block might be overlaped.


Chris


On Thu, Nov 14, 2002 at 10:38:51AM -0500, Bill Rugolsky Jr. wrote:
>  
> Are you talking about convertfs?
> 
> http://tzukanov.narod.ru/convertfs/
> 
> Convertfs is a very neat trick, and with a little work, could be quite
> robust for converting between filesystems that are well-supported by
> Linux.  But the problem of using convertfs from a migration standpoint
> is that one needs robust write support to the filesystem that one is
> converting from, and the more obscure the system, the less likely that
> this will work.
> 
> So what to do?
> 
> If you must, I'd suggest doing the same trick as convertfs, but on the
> native platform that you are migrating from.  You can create a sparse
> file the size of your filesystem, and use a *userland* implementation
> of ext2 to move files into that sparse fs.  [Alternatively, export
> the partition using NFS or Samba, and do the file moves from a Linux
> host with the sparse Linux filesystem mounted using loopback over
> NFS/Samba or via [E]NBD.  This also gives you the ability to use
> filesystems other than ext2/3, since you are using Linux to move
> the data.]
> 
> If possible, produce a block map index file on the native platform
> (using whatever BMAP-like feature is available.  If not, use the
> Linux UFS filesystem in readonly-mode to do the same.  Finally, remap
> the blocks, either on the native platform or on Linux.
> 
> As with convertfs, this can be done as three separate programs, and
> really the only platform-specific magic is in producing the block map
> index for the inode.
> 
> When you are done, kindly release it under the GPL. :-)
> 
> Regards,
> 
> 	Bill Rugolsky
> 
> 
> 
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