On Sat, Sep 19, 2015 at 12:47:25PM +1000, Dave Chinner wrote: > On Wed, Sep 16, 2015 at 07:21:59PM -0600, Andreas Dilger wrote: > > If you add "-b 1024" to the mke2fs command line to use 1KB instead of 4KB blocks, and reduce the sizes by a factor of 4 does the problem still happen? That would make it easier for someone else to test, since it would only need a 4-5TB disk instead of a 19Tb array. > > Sparse files on XFS using loopback will allow you to simulate > devices larger than 16TB easily. You can turtle it all the way down, > too, to create the xfs filesystem on a loopback device on a sparse > file on ext4.... > > Doing this sort of thing lets me know, for example, that the > mkfs.ext4 defaults fail on a 500TB device... > > # xfs_io -f -c 'truncate 500t' /mnt/xfs/fs.img > # ls -lh /mnt/xfs > total 0 > -rw------- 1 root root 500T Sep 19 12:41 fs.img > # mkfs.ext4 /mnt/xfs/fs.img > mke2fs 1.42.13 (17-May-2015) > /mnt/xfs/fs.img: Cannot create filesystem with requested number of inodes while setting up superblock Whee. I guess one would need to turn on meta_bg at mkfs time (which scatters the group descriptors across the disk instead of (failing to) sandwich them in a single blockgroup... and fix the overhead calculation in ext2fs_initialize to calculate the maximum BG overhead correctly, since it doesn't seem to know about metabg. Of course there's the question of whether or not we really /want/ people formatting 500T ext4 filesystems. meta_bg is not turned on by default, so the defaults will still fail unless they know to pass that option. (Frankly, doing so is probably insane.) --D > # > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > -- > 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 -- 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
