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Re: using non-default blocks per group

On Oct 19, 2001  12:52 -0700, Jeffrey W. Baker wrote:
> I've been playing with the -g switch to mke2fs, which controls the blocks
> per group.  This switch isn't documented.  I've been using it to balance
> metadata traffic on RAID 0.
> This seems to work fine in ext2.  Will I have any problems with ext3 where
> the blocks per group is not a power of 2?

This shouldn't cause any problems anywhere.  It may be that some poorly
coded ext2 tools will use "blocksize*8" as the number of blocks per group,
but that is just plain wrong (even if it matches 99.9% of the configs out
there).  Ext3 does nothing (AFAIK) to change the behaviour of this part
of the code.

You do know about the "-R stride" option for mke2fs?  It is also supposed
to help balance bitmap I/O across multiple disks.  It doesn't help with
inode tables, however, but since they are normally quite large, they should
be striped across multiple disks anyways.

Cheers, Andreas
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert

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