Re: Disk hardware caching, performance, and journalling

[Chris Wedgwood]

On Sat, Nov 24, 2001 at 11:08:17AM -0800, Andrew Morton wrote:

    In theory, yes.  In my opinion, no.  For ext3, at least.  Caching
    isn't bad per-se.  It's reordering which can break the journalling
    constraints.

Some disks[1] most definately do reorder;  I've actually been able to
demonstrate this in some circumstances (it wasn't trivial to
produce and required several attempts).

  --cw

[1] SCSI, which we know does and will reorder writes when a barrier
    isn't specificed, it appears IDE drives can do the same but lack of
    hot-swap makes testing tedious :)