[Ocfs-devel] Re: [Ocfs-users] ocfs issues with 9.2.0.3

[Karthik Ramadoss]

Wim,

   Thanks for the reply. Here are a few observations.

* I am using direct_io for file copies..
* Yes, I can reproduce this with Oracle. Couple of instances where I
can clealy tell..
    a. RMAN restore (16GB) on ocfs takes 6 hours compared to 45 minutes
in ext3 filesystem. I know I shouldn't be comparing ocfs with ext3 but
it still seems a looooot slower. We dont have a raw disk setup to get an
actual comparison. But I will use the benchmarks you post to compare.
   b. The hanging issue happens even I create or resize a tablespace
from Oracle. We saw this issue first with ocfs 1.0.9.9 when we upgraded
from 1.0.9.4 but even rolling back to 1.0.9.4 didnt solve it now. 

Regards
Karthik Ramadoss
Oracle Apps DBA
The ASU Group

>>> Wim Coekaerts <wim.coekaerts at oracle.com> 11/11/2003 11:38:26 AM
>>>
> a few pointers to the issues..
> 1. OCFS read/write performance is way lower than a read/write to a
raw
> device.. i can give you some comparison numbers..

and I assume you are doing on directio's.

> 2. Writes to shared disk with ocfs would get locked up by one
server..
> it doesnt have to even be an oracle process.. just a file copy will
> lock up the directory and the other server trying to access the same
> directory in the shared disk will just hang (os process has a state
> 'D').... the only way to free
> this up is to unmount the shared disks from the other server.. even
> killing the
> process which is hanging doesnt work (kill -9).. 'strace -p' also
hangs
> and obviously the process is waiting on io..

and can you reproduce this WITH oracle ?

point is, 1- you should do directio comparisons and All/Every
benchmark
we ever did we were within at most 2% of raw. but yuou have to do IO
like we expect Oracle to do and 2- it's not a general purpose
filesystem
so regular like file stuff iwll not work

I will post some perforamnce results on here
and I suggest you go to http://oss.oracle.com/projects/oss, go to the
docs tab and read thedifferent thinsg that are on there
specifically the do's and don'ts  etc. 

if you use it for what it's built for, it works just fine.
anyways let me post some results when I get around to it 
and read the docs that will help