Bugger, I don't have access to any RHLinux system at the moment...
A couple of things to check, from a vague memory:
1- What file system block size for each db
2- Are datafiles for all dbs on same file system
3- What is the value of filesystemio_options for each db.
4- In sqlplus, what does this produce on each db:
show parameter priority
5- Check and compare SGA memory-related sizes for each db.

Cheers
Nuno Pinto do Souto
DBA Team, Australia/NZ

-----Original Message-----
From: [address removed]
[mailto:[address removed]] On Behalf Of Yury Velikanov
Sent: Wednesday, 26 May 2010 11:18 AM
To: [address removed]
Subject: [Sydney-Oracle] I need you help. Odd performance difference
comparing 4k data block size and 8k databases

Hello everyone,

I need any idea that may came you your head to find out the reason for
the following problem. Please do not hesitate to through any
suggestions and I will  check those for you.
This is a super-duper new Dell server, 11GR2, Red Hat Enterprise Linux
Server release 5.4.

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