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To: Dieter =?iso-8859-15?q?N=FCtzel?= <Dieter.Nuetzel@hamburg.de>
cc: James Bottomley <James.Bottomley@SteelEye.com>,
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Subject: Re: [PATCH] 2.4.x write barriers (updated for ext3) 
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Dieter.Nuetzel@hamburg.de said:
> How do you checked it? 

I used sginfo from Doug Gilbert's sg utilities (http://www.torque.net/sg)

The version was sg3_utils-0.98

Dieter.Nuetzel@hamburg.de said:
> But when I use "scsi-config" I get under "Cache Control Page": Read
> cache enabled: Yes Write cache enabled: No 

I believe write cache enabled is the state of the WCE bit and read cache 
enabled is the inverse of the RCD bit, so you have a write through cache.

I think that notwithstanding the spec, most drives are write through (purely 
because of the safety aspect).  I suspect certain manufacturers use write back 
caching to try to improve performance figures (at the expense of safety).

James


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