Thread: Small correction in http://www.postgresql.org/docs/9.0/interactive/wal-reliability.html
Small correction in http://www.postgresql.org/docs/9.0/interactive/wal-reliability.html
From
Achilleas Mantzios
Date:
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. ' -- Achilleas Mantzios
Re: Small correction in http://www.postgresql.org/docs/9.0/interactive/wal-reliability.html
From
Greg Smith
Date:
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.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
Re: Small correction in http://www.postgresql.org/docs/9.0/interactive/wal-reliability.html
From
Robert Haas
Date:
On Fri, Jun 17, 2011 at 10:54 PM, Greg Smith <greg@2ndquadrant.com> 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