Increase EXT3 format speed.

Alex Bligh alex at
Mon Feb 28 18:33:57 UTC 2011

--On 28 February 2011 08:25:03 -0700 Andreas Dilger <adilger at> 

> You can speed up mke2fs by reducing the inode count (-i or -N) if your
> average file size is over 8kB, reduce the journal size (-J size=4) and/or
> use the lazy_journal_init patch I posted recently, and/or use the
> lazy_itable_init option. I assume since format performance is important
> that you do it often and the risk of an uninitialized inode table is low.
> Or, you could use ext4, which is also faster at runtime, not just format
> time.

If you are doing this a lot, another alternative is to format a sparse file,
keep this between formats, and copy the sparse file on.

There are plenty of utilities to do that, including one here:

If you are quite sure your USB device is completely blank (i.e.
all sectors zero), run with -n, in which case it will only write
the non-zero sectors and read nothing. If you are not completely sure
your USB device is blank, don't run with -n, and discover that this will be
probably be slower than a straight format as it will have to read every

Alex Bligh

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