[clug] Tips for improving ext3 performance

[Daniel Pittman]

"Chris Smart" <chris at kororaa.org> writes:

> Been reading up a little about this lately, does anyone out there have
> any tips or suggestions for improving ext3 performance for a desktop
> machine?
>
> Some things that come to mind are changing the journal type, 

Use the largest journal size, and a longer commit interval, to reduce
contention and stalls due to journal writes or flushing for space.

The commit interval increases your risk window for data loss, so don't
just raise it blindly, think about what you can afford.

> changing atime, 

Using noatime, or relatime, will significantly reduce the number of
inode writes on access, which will in turn reduce journal load, and so
improve performance.

> using a stride size when using raid and offsetting the partition start
> to align with stripe.

This should just come by magic, since the mkfs tools interrogate the
underlying RAID for details.  (As I understand it, with a sufficiently
recent version, etc, etc, which should be "it just works" today.)

> Anyone had a play with this sort of thing?

If you can, placing the journal on an external device will deliver a
much, much bigger performance boost that these other changes.  It allows
your data and metadata writes to occur in parallel.

If you have an underlying RAID mirror an external bitmap can also
achieve performance gains in some cases.

Regards,
        Daniel