On Fri, Jun 09, 2017 at 01:35:12PM +0800, Qu Wenruo wrote: > >ex: Like 5% of ext3/4 free space is needed for > >btrfs-convert to succeed? > > That's hard to say. > > It's not only dependent on how much free space is here, but also how > continuous the free space is. > > In convert, it needs the following continuous space at least: > > 1) 64K for temporary btrfs super block > 2) 4M for system chunk > 3) 32M for metadata chunk. > > Further more, we want to keep chunks at reasonable size, that's to say we > want each used data space on old fs is covered by a chunk >= 32M. > > For worst case, if the free space in old fs is so scattered, either we can't > find continuous for sys/meta chunk, or used data space is so scattered that > we can't find free space after rounding up data chunks, then we can't do > convert. > > Thanks, > Qu
Thanks for the details, Qu. I was thinking about adding a free-space check (based on total blocks/free block stat from source superblock) before btrfs-convert begins, looks like its more complex than i thought. Cheers. Lakshmipathi.G -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
