Cluster file systems versus raw devices in Oracle RAC

  • From: Antonio Belloni <toni_belloni@xxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Mon, 26 Dec 2005 18:02:32 +0000 (GMT)


Does anyone using cluster file systems in a RAC 10gR2
installation, specifically IBM?s GPFS?

I?ve visited a company that is running RAC 10gR2 in
AIX over raw devices. Why someone would choose to use
raw devices , with all the problems to administer ,
when all the modern file systems are so powerful? Is
there any issues when using cluster file systems +
RAC? Is there considerable performance benefits when
using raw devices with RAC ?

I´ve always used Oracle stand alone instances over
file systems (since version 7) , and performance was
always very good. I´ve tested raw devices almost 10
years ago , and even in that time (the hardware today
is much better - SAN , 15K rpm disks , huge caches -
and the file systems software today is much better)
the cost to administer it does not compensate the
benefits (only 5% more faster than file systems in
Oracle 7). 

So , as I didn't see a line in the Oracle RAC
documentation saying that RAC only works over raw
devices and besides any limitations imposed by RAC ,
why use raw devices nowadays ?

Antonio Belloni 


Yahoo! doce lar. Faça do Yahoo! sua homepage. 


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