Re: RAID controller safety

[Alan Cox]

On Gwe, 2005-12-30 at 08:18 -0800, Kenny Simpson wrote:
> That's what I read in the comments too, but looking at the code I only ever see it set to
> write-back.  I verified this with blktool - our controllers have no battery, and blktool showed
> the i2o-wcache state as write-back.

blktool doesn't support i2o control as far as I am aware. The blk level
generic ioctls are just too crude to control it properly.

> However, I was also told that the i2o_block driver lacks barrier support, so even in the
> write-back case, the controller won't be told to flush/sync.

Correct, but it should only ever enable this in the battery backed case.
Otherwise it uses the per command control bits to decide what mode it
wishes to use for each I/O

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