doc hdparm also support SATA

from the pg doc：
http://www.postgresql.org/docs/devel/static/wal-reliability.html :On Linux,
IDE drives can be queried using hdparm -I; write caching is enabled if
there is a * next to Write cache. hdparm -W 0 can be used to turn off write
caching. SCSI drives can be queried using
sdparm<http://sg.danny.cz/sg/sdparm.html>.
Use sdparm --get=WCE to check whether the write cache is enabled and sdparm
--clear=WCE to disable it.

from the hdparm man page :
http://linux.die.net/man/8/hdparm :hdparm - get/set SATA/IDE device
parameters

so,the doc is out date, it should mention hdparm also support SATA.

and this doc section current contains more IDE than SATA driver , but
nowadays, IDE driver is nearly dead, it hardly buy one IDE hard disk on the
market. so we should write more doc about SATA than IDE.

best regards,
--
Jov
blog: http:amutu.com/blog <http://amutu.com/blog>