Re: randomize_va_space
- From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 10 May 2023 14:56:19 -0400
On 5/9/23 18:37, Alan Sterger wrote:
Hello Listers,
On a multi Oracle homed (12c and 19c) RHEL 7.9 server, have started to
observe infrequent (every 2 months) 'ORA-00445: background process
"m001" did not start after 120 seconds' errors from both 12c and 19c
instances. Seeing the same error from two different Oracle releases
sort of points to a server kernel issue, specifically
kernel.randomize_va_space=2.
MOS Note 1345364.1 implies randomize_va_space was a thing in the past
(11g,12c). However, appears Oracle is still recommending disabling in
19c on Oracle Cloud Infrastructure.
What is your on-prem randomize_va_space?
Thanks,
-- Alan Sterger
--
//www.freelists.org/webpage/oracle-l
I always set it to 0 on my remaining RHEL 7 installations, regardless of
the database version. Address space randomization doesn't look like a
useful feature from my perspective. Here is the Linux documentation for
the parameter:
randomize_va_space
<
https://www.kernel.org/doc/html/latest/admin-guide/sysctl/kernel.html#id73><
https://www.kernel.org/doc/html/latest/admin-guide/sysctl/kernel.html#randomize-va-space>
This option can be used to select the type of process address space
randomization that is used in the system, for architectures that support
this feature.
0
Turn the process address space randomization off. This is the default
for architectures that do not support this feature anyways, and kernels
that are booted with the "norandmaps" parameter.
1
Make the addresses of mmap base, stack and VDSO page randomized. This,
among other things, implies that shared libraries will be loaded to
random addresses. Also for PIE-linked binaries, the location of code
start is randomized. This is the default if the |CONFIG_COMPAT_BRK|
option is enabled.
2
Additionally enable heap randomization. This is the default if
|CONFIG_COMPAT_BRK| is disabled.
There are a few legacy applications out there (such as some ancient
versions of libc.so.5 from 1996) that assume that brk area starts just
after the end of the code+bss. These applications break when start of
the brk area is randomized. There are however no known non-legacy
applications that would be broken this way, so for most systems it is
safe to choose full randomization.
Systems with ancient and/or broken binaries should be configured with
|CONFIG_COMPAT_BRK| enabled, which excludes the heap from process
address space randomization.
However, the parameter no longer exists in Oracle Linux 8:
[oracle@ora23c ~]$ sudo sysctl -p|grep -i random
[oracle@ora23c ~]$ cat /etc/oracle-release
Oracle Linux Server release 8.7
[oracle@ora23c ~]$
And yes, the VM houses Oracle 23c.
[oracle@ora23c dbhomeFree]$ sqlplus scott/tiger@localhost/freepdb1.home.com
SQL*Plus: Release 23.0.0.0.0 - Developer-Release on Wed May 10 14:55:05 2023
Version 23.2.0.0.0
Copyright (c) 1982, 2023, Oracle. All rights reserved.
Last Successful login time: Sat Apr 15 2023 21:49:22 -04:00
Connected to:
Oracle Database 23c Free, Release 23.0.0.0.0 - Developer-Release
Version 23.2.0.0.0
SQL>
--
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com
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