Re: slow i/o with a raid 50 on a 3ware controller

[John R Pierce <pierce@xxxxxxxxxxxx>]

On 8/6/2014 5:32 PM, Markus Falb wrote:
> Do you have barriers enabled?
> Just another shot in the dark, but 5 didn't have that.
> If you have battery backed Cache with your Controller, you can safely
> disable barriers anyway.
are you sure about this?  thats not my understanding.

What I've been told is, the battery backed write cache just lets you 
enable writeback caching in the raid controller, write barriers at the 
various OS layers still have to be respected, as they ensure certain 
writes are completed in order.



-- 
john r pierce                                      37N 122W
somewhere on the middle of the left coast

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