kernel: EXT3-fs: Unsupported filesystem blocksize 8192 on md0.

[Coly Li]

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In ext3, it is better to make the filesystem block not large than page size. On
x86 the typical page size is 4KB.

Coly

Ulrich Windl wrote:
> Hi,
> 
> I made an ext3 filesystem with 8kB block size:
> # mkfs.ext3 -T largefile -v -b 8192 /dev/md0
> Warning: blocksize 8192 not usable on most systems.
> mke2fs 1.38 (30-Jun-2005)
> Filesystem label=
> OS type: Linux
> Block size=8192 (log=3)
> Fragment size=8192 (log=3)
> 148480 inodes, 18940704 blocks
> 947035 blocks (5.00%) reserved for the super user
> First data block=0
> 290 block groups
> 65528 blocks per group, 65528 fragments per group
> 512 inodes per group
> Superblock backups stored on blocks:
>         65528, 196584, 327640, 458696, 589752, 1638200, 1769256, 3210872,
>         5307768, 8191000, 15923304
> 
> Writing inode tables: done
> Creating journal (32768 blocks): done
> Writing superblocks and filesystem accounting information: done
> 
> This filesystem will be automatically checked every 22 mounts or
> 180 days, whichever comes first.  Use tune2fs -c or -i to override.
> 
> When mounting it as ext2 (by mistake), the kernel says:
> EXT2-fs warning (device md0): ext2_fill_super: mounting ext3 filesystem as ext2
> 
> When finally mounting the filesystem as ext3, the kernel says:
> kernel: EXT3-fs: Unsupported filesystem blocksize 8192 on md0.
> 
> I don't quite understand: About any larger filesystem of today can support blocks 
>> 4kB. What is the problem here?
> 
> Kernel is 2.6.16.46-0.12-default (SUSE SLES10 SP1) on IA64
> 
> Regards,
> Ulrich

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