SAS Raid - mfi driver

[Wilko Bulte]

On Wed, Nov 01, 2006 at 12:34:22AM +0100, Fredrik Widlund wrote..
> Yes, it forces writeback even when the controller has no BBU. Choosing 
> WBack itself will default back to WThru. It's dangerous, but I guess it 
> should be much less dangerous than using for example softupdates. We 
> have little choice until our order of BBUs get here, since the 
> performance degradation of wthru would make it unusable for us.

At least hook the machine up to an UPS if you have one.

> Ivan Voras skrev:
> >Fredrik Widlund wrote:
> >  
> >>Solved my issue with LSI 8480E without BBU. With "write: BadBBU",
> >>"cache: enabled", and "io: cached", performance rose to around 200MB/s
> >>from 20MB/s.
> >>    
> >
> >I don't know what "BadBBU" is, but from some Googling it seems to be a
> >setting that overrides BBU detection, and enables write caching even if
> >the system believes BBU is broken or missing. If true, this may be
> >dangerous for data consistency.
> >
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-- 
Wilko Bulte				wilko at FreeBSD.org