Re: hdparm Write Cache automatically turned back on?

On Mon, Jun 23, 2014 at 4:14 PM, Andrew Puschak <apuschak(at)gmail(dot)com> wrote:
> Hello,
>
> I have a set of servers running PostgreSQL 8.4 and I'm building a second set
> now. When I built them a few days ago, I turned off the Write Cache using
> hdparm as described in the manual
> http://www.postgresql.org/docs/8.4/static/wal-reliability.html Now, after
> transport and rebooting Write Cache is back on. I checked my other servers
> which had it off before and all of them have it turned on again too. I've
> searched for the issue but haven't found anything. I wrongly assumed setting
> the hard drive would be a one time setting.
>
> Has anyone experienced this or know what might be happening?
>
> The hard drives are WD 500GB black, the new servers are running the latest
> CentOS 6.5 with latest updates. The versions of hdparm are below.

this is more of a o/s question. see here:
http://www.linuxquestions.org/questions/debian-26/how-can-i-permanently-turn-off-'write-cache'-debian-424136/

"You can put the hdaprm command in /etc/hdparm.conf file towards the
end. So Everytime you reboot your system, it will execute the command
and you will be able to disable the write cache"

merlin