Messages in this thread | | | Date | Mon, 30 Jun 2003 17:42:24 +0400 | From | Hans Reiser <> | Subject | Re: File System conversion -- ideas |
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Jesse Pollard wrote:
>On Sunday 29 June 2003 14:45, rmoser wrote: > > >>*********** REPLY SEPARATOR *********** >> >>On 6/29/2003 at 8:42 PM viro@parcelfarce.linux.theplanet.co.uk wrote: >> >> >>>On Sun, Jun 29, 2003 at 08:28:47PM +0100, Jamie Lokier wrote: >>> >>> >>>>Consider that many people choose ext3 rather than reiser simply >>>>because it is easy to convert ext2 to ext3, and hard to convert ext2 >>>>to reiser (and hard to convert back if they don't like it). I have >>>>seen this written by many people who choose to use ext3. Thus proving >>>>that there is value in in-place filesystem conversion :) >>>> >>>> >>>Uh-huh. You want to get in-kernel conversion between ext* and reiserfs? >>>With recoverable state if aborted? Get real. >>> >>> >>no, in-kernel conversion between everything. You don't think it can be >>done? It's not that difficult a problem to manage data like that :D >> >> > >You are ASSUMING that the new filesystem requires lessthan or equal amount >of metadata. This is NOT always true. A conversion of a full EXT2 to Riserfs >would fail simply because there is no free space to expand the needed >additional overhead. > Uh, you mean converting reiserfs to ext2 would fail.... we are more space efficient....
> >Going in the other direction usually is possible (again, depending on the >filesystem) but there are exceptions... Try converting an EXT2 to DosFS. >In place. And maintain a recoverable state when aborted. > >Not gonna happen. > >Too much depends on what the target filesystem is, and what it may require. > >Consider another - switching to an extent filesystem... If the datablocks >don't move, then you need MORE extents than the current indirect pointers. >And each extent is LARGER than the indirect pointers. > >Then you have to compress/condense the extents (requiring shuffling data >blocks around to reduce the number of extents). Each requires free space >to do it's work, and the amount of free blocks is not the same. > >Faster to do a copy. more reliable too. and recoverable. >- >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html >Please read the FAQ at http://www.tux.org/lkml/ > > > >
-- Hans
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