I think somebody did a small test. Using regular files - Oracle
transfers data to memory buffer of ext2 filesystem actually.
This buffer may be of a huge size. As you can see in that situation
there is a strange "double buffering". Raw devices eliminate such
a misuse of memory buffers. Did not compare it on Linux yet, but
on Solaris raw devices are 2x faster than regular files.
Pawel
Tim X wrote:
>>>>>> "3" == 3 <trzeci_at_tiger.com.pl> writes:
>
> 3> Felix Rauch wrote:
> >> it seems I can't get Oracle to work with raw devices on Linux and
> >> would appreciate any help.
> >>
> >> I installed Oracle with raw device support, but generated all the
> >> system tables in regular files in the file system (I thought
> >> mixing regular files and raw devices for different table spaces
> >> should be possible and seemed easier to set up). Then I bound
> >> /dev/raw5 to /dev/sdb9, but when I try to create a tablespace on
> >> the raw device I get:
> >>
> SVRMGR> create tablespace "DATA" datafile '/dev/raw5';
> >> create tablespace "DATA" datafile '/dev/raw5' * ORA-01119: error
> >> in creating database file '/dev/raw5' ORA-27059: skgfrsz: could
> >> not reduce file size Additional information: 2
> >>
> >> The use of "reuse" doesn't seem to help:
> >>
> SVRMGR> create tablespace "DATA" datafile '/dev/raw5' reuse;
> >> create tablespace "DATA" datafile '/dev/raw5' reuse * ORA-01119:
> >> error in creating database file '/dev/raw5' ORA-27059: skgfrsz:
> >> could not reduce file size Additional information: 2
> >>
> >> Any hints on what I should do to get it running or what Oracle
> >> actually requires from the raw device to work?
> >>
> >> My environment ist: - SuSE Linux 6.0 (I know this is old, but I
> >> have to use this version for a performance comparison of a
> >> colleagues work) - Oracle8 Release 8.0.5.0.0 - Production (At
> >> least that's what svrmgrl prints on startup.) - Linux kernel
> >> 2.4.3 (I also tried 2.4.18)
> >>
> >> My Background: I'm not a database expert, but I'm doing research
> >> on distributed file systems.
> >>
> >> Regards, Felix
> >>
>
> 3> Try to create tablespace on a regular file, next dd this file
> 3> (database must be stopped) onto a raw device. Replace the file
> 3> with symbolic link to the raw device. I am using this method on
> 3> kernel 2.4.20 and it works fine.
>
> Just FYI, I think there was a thread here a few weeks ago where
> someone posted some results form doing some test comparing raw device
> with ext2 and the results indicated ext2 was actually faster than
> using a raw device. the thread should be locatable via google.
>
> Tim
Received on Fri Mar 07 2003 - 11:51:59 CST
