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List:       freebsd-scsi
Subject:    Re: sync cache
From:       Bernd Walter <ticso () cicely5 ! cicely ! de>
Date:       2002-06-13 0:19:44
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On Wed, Jun 12, 2002 at 08:50:33PM +0200, Joerg Wunsch wrote:
> Bernd Walter <ticso@cicely5.cicely.de> wrote:
> 
> > Even if they do not need the command they should have implemented
> > it as a nop.
> 
> Why?
> 
> > Possibly this command is even required in recent SCSI specs.
> > Such a lousy implementation does not create trust in firmware.
> 
> Of course, since the entire concept of `cache memory' is optional
> to the SCSI block device model, the implementation of SYNCHRONIZE
> CACHE is optional as well.

I have read the specs.
It is still optional if the device has no write cache.
This is not the case for a raid controller which allows the drives
behind to have write cache enabled.
I strongly hope the controller in question explicitly disables it.
Nevertheless I would expect it to be available on any modern device.
OK - I have to revert that it can be a nop if there is nvram based
cache.

-- 
B.Walter              COSMO-Project         http://www.cosmo-project.de
ticso@cicely.de         Usergroup           info@cosmo-project.de


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