Re: Disk hardware caching, performance, and journalling

From: Chris Wedgwood (cw@f00f.org)
Date: Sun Nov 25 2001 - 04:22:14 EST


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 :)
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This archive was generated by hypermail 2b29 : Fri Nov 30 2001 - 21:00:18 EST