RE: ASM is single point of failure ?

  • From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Mon, 8 May 2006 14:31:31 -0700

 >>>On Mon, May 8, 2006 21:32, Kevin Closson said:
>>>> ...VxVM runs in kernel mode. Kill(1) sends a signal. You 
>>>What is less plesant with ASM, actually, is a kind of buffered "I/O"
>>>between database and ASM instance processes. I mean, the 
>>>blocks should be shipped between them somehow, right? So 
>>>some additional CPU cycles are definitely there as well as 
>>>more syscalls, context switches, ipc delays.

The misconceptions are the most frightening aspect of ASM. 

People are willing to use it and have ZERO idea what it is.
Oddly, I find people fearing things that do not relate whatsoever 
(such as the above), but ignoring the bold, glaring issues. 
It just bogles my mind. 

ASM is not in the I/O code path. Huh, what did he say? Oracle
positions and performs reads and writes and that is done with
either libC, LibODM or if you are a real experimental type ASMLib (on
Linux). There are no comms between a shadow process and an ASM process
for I/O (e.g., db file sequential read, direct path write, etc). There 
is for metadata ops, such as adding a datafile, or adding an extent, 
dropping a datafile, etc...


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