On Jul 18, 2008 21:59 +0200, Goswin von Brederlow wrote: > Won't tune2fs be able to adjust the descriptor size? I thought all the > keeping compatibility with ext2/3 was so people could upgrade without > reformating. Or is that maxime broken with 64bit support? There is definitely compatibility between ext3 and ext4 - you can mount and use any ext3 filesystem under ext4. That doesn't mean that ext3 filesystems will have all of the features in ext4 available to them. Some features like 65000-subdir limit, mballoc, extents will work on all ext3 filesystems. Other features like nanosecond timestamps and fast extended attributes will work on newer ext3 filesystems because mke2fs was changed to default to 256-byte inodes. Being able to transparently support 64-bit filesystems was initially attempted, but proved to be problematic, and the likelihood of users resizing from < 16TB to > 16TB was decided to be rare enough that having to do an offline operation to resize the group descriptor blocks was considered acceptable. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
