Hi, On Sun 02-09-18 23:58:56, Liu Bo wrote: > My question is, > Is there a way to calculate how much space metadata has occupied? > > So the case I've run into is that 'df /mnt' shows > > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/sdc 882019232 26517428 811356348 4% /mnt > > but 'du -s /mnt' shows > 13347132 /mnt > > And this is a freshly mounted ext4, so no deleted files or dirty data exist. > > The kernel is quite old (2.6.32), but I was just wondering, could it > be due to metadata using about 13G given the whole filesystem is 842G? Yes, that sounds plausible. > I think it has nothing to do with "Reserved block counts" as df > calculates "Used" in ext4_statfs() by "buf->f_blocks - buf->f_bfree". > > So if there is a way to know the usage of metadata space, via either > manual analysis from the output of dumpe2fs/debugfs or a tool, could > you please suggest? So journal takes up some space. Debugfs command: stat <8> Inode table takes lots of blocks: stats search for "Inode count", multiply by "Inode size". Then there are bitmap blocks - count 2 blocks for each group. The rest of overhead should be pretty minimal. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
