Messages in this thread |  | | | Date | Fri, 30 Dec 2005 10:58:40 -0800 (PST) | | From | Kenny Simpson <> | | Subject | Re: RAID controller safety |
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--- Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: > 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.
From man blktool dated August 2004: i2o-wcache Query or set an I2O block device's write cache.
> > > 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
So all writes would be treated as syncronous in the write-through case (no battery), making fsync a no-op?
-Kenny
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