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From: Robert Haas <[email protected]>
To: Greg Smith <[email protected]>
Cc: [email protected]
Subject: Re: Small correction in http://www.postgresql.org/docs/9.0/interactive/wal-reliability.html
Date: Mon, 10 Oct 2011 13:27:26 -0400
Message-ID: <CA+TgmoYF_QQoTWT-8S3tF8hwvD8rsbopqcCp-xO2Gr6o=X7jkQ@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
	<[email protected]>

On Fri, Jun 17, 2011 at 10:54 PM, Greg Smith <[email protected]> wrote:
> On 06/17/2011 07:55 AM, Achilleas Mantzios wrote:
>>
>> It reads :
>> 'On FreeBSD, IDE drives can be queried using atacontrol, and SCSI drives
>> using sdparm.'
>> but it should be:
>> 'On FreeBSD, IDE drives can be queried using atacontrol, and SCSI drives
>> using camcontrol.'
>>
>
> FreeBSD's Common Access Method (CAM) looks to be the preferred driver layer
> to interrogate.  sdparm is available on Linux and FreeBSD, but it's a
> second-class citizen talking to CAM on the latter.  To quote from one of the
> docs on it, FreeBSD sdparm "SCSI commands are routed through the CAM
> pass-through interface".  Talking directly to it with camcontrol does seem
> to be the preferred route for some things.
>
> However, the UI to sdparm is a bit easier to use when it is available.
>  Actually changing the write cache state with camcontrol requires black
> magic--you have to construct the right SCSI packet by hand.  I can't find
> any example.
>
> Bruce just touched this section of the docs recently, so this part actually
> reads just:
>
>         SCSI drives use <command>sdparm</command>.
>
> Now.  Perhaps the following makes sense:
>
>         SCSI drives can be queried using <command> camcontrol
> identify</command>, and the write cache both queried and changed using
> <command>sdparm</command> when available.

Done, in master and REL9_1_STABLE.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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