RE: AIX Concurrent I/O for Oracle archive logs

  • From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
  • To: Subodh Deshpande <deshpande.subodh@xxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <Oracle-L@xxxxxxxxxxxxx>
  • Date: Tue, 25 May 2010 11:57:25 -0700

Hi Subodh,

Sorry, but I think you have it backwards - the OS block size must be equal to 
or smaller than the DB block size:

From http://public.dhe.ibm.com/partnerworld/pub/whitepaper/162b6.pdf:

"put the data files on one or more file systems with the agblksize equal to the 
smallest database block size that is used for table spaces in data files on 
that file system, or 4096, whichever is smallest"

In my case, I've got an 8k db_block_size and am using the default OS blocksize 
of 4k for my data files, and I have my online redo logs on a separate file 
system with agblksize=512 and both of those are working fine - no problems or 
questions there.  My question is only for the archive logs specifically.  
Oracle says not to put archive logs on a CIO file system, but why?!?

Thanks,
Brandon

From: Subodh Deshpande [mailto:deshpande.subodh@xxxxxxxxx]

OS block size should be multiple of oracle db block size while installing db 
usually I keep this ratio as 1:2 i.e. if my os block size is 4096 then my 
oracle block size will be 2048


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