Sunday, 26 January 2014

configure DNS for Installtion of Oracle Grid Infrastructure RAC cluster

1.create these files :-  forward.zone,reverse.zone and named.rfc1912.zones into /var/named/chroot/var/named

2.content of forward.zone :-
$TTL 86400
@          IN     SOA    rac.  rac. (
                         42 ; serial (d. adams)
                         3H ; refresh
                        15M ; retry
                         1W ; expiry
                         1D ) ; minimum
@          IN   NS     rac.
rac       IN   A      192.168.72.128
localhost                     IN A    127.0.0.1
rac2                          IN A    192.168.72.129
rac-vip                       IN A    192.168.72.102
rac2-vip                      IN A    192.168.72.104
rac-cluster-scan              IN A    192.168.72.106
rac-cluster-scan              IN A    192.168.72.107
rac-cluster-scan              IN A    192.168.72.108

3.content of reverse.zone :-
$TTL 86400
@        IN     SOA    rac.  rac. (
                         42 ; serial (d. adams)
                         3H ; refresh
                        15M ; retry
                         1W ; expiry
                         1D ) ; minimum
@         IN   NS   rac.
128.72.168.192      IN   PTR  rac.
1.0.0.127           IN   PTR  localhost.
129.72.168.192      IN   PTR  rac2.
102.72.168.192      IN   PTR  rac-vip.
104.72.168.192      IN   PTR  rac2-vip.
106.72.168.192      IN   PTR  rac-cluster-scan.
107.72.168.192      IN   PTR  rac-cluster-scan.
108.72.168.192      IN   PTR  rac-cluster-scan.

4.content of named.rfc1912.zones :-
zone "rac" IN {
                 type master; 
                 file "forward.zone"; 
                  
};
zone "72.168.192.in-addr.arpa" IN {
                 type master;
                 file "reverse.zone";
                 };
5.change the ownership and owner of these files by below command :-

chown named:named *.*

6.create the named.conf into /var/named/chroot/etc

7.content of named.conf :-

options {
listen-on port 53 { 192.168.72.128; };
# listen-on-v6 port 53 { ::1; };
        directory "/var/named";
        recursion yes;
        };
logging {
        channel default_debug {
        file "data/named.run";
        severity dynamic;
        };
};
  include "named.rfc1912.zones";

8.change the ownership and owner of these files by below command :-

chown named:named *.*

9.config the file /etc/resolv.conf

10.content of /etc/resolv.conf

search rac
nameserver 192.168.72.128

11.change the ownership and owner of these files by below command :-

chown named:named *.*

12. start the named service :-

service named start

chkconfig named on

13.Test the DNS IP reachability :-

nslookup rac

nslookup rac2

nslookup rac-cluster-scan

14. contents of /etc/hosts file :-

cat /etc/hosts
# that require network functionality will fail.
127.0.0.1       localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6
#eth1 - PUBLIC
192.168.72.128 rac
192.168.72.129 rac2
#VIP
192.168.72.102 rac-vip
192.168.72.104 rac2-vip
#eth2 - PRIVATE
192.168.140.128 rac-pvt
192.168.140.129 rac2-pvt

Note :- Make all these changes to all node , by interchanging the node name .

VOILA ----> Now you ready to Oracle Grid Infrastructure Installation ;) Here I am sharing one snap :-


Thursday, 2 January 2014

direct path reads

To resolve the direct path reads wait event :-

Please check the below views :-

V$SESSION_EVENT ->  to identify sessions with high numbers of waits
V$SESSTAT ->  to identify sessions with high "physical reads direct" (statistic only present in newer Oracle releases)
V$FILESTAT ->  to see where the IO is occurring
V$SQLAREA ->  for statements with SORTS and high DISK_READS (which may or may not be due to direct reads)

Solution approcah :-

If the file indicates a temporary tablespace check for unexpected disk sort operations.
Ensure Parameter DISK_ASYNCH_IO -> is TRUE .
Ensure the OS asynchronous IO is configured correctly.
Check for IO heavy sessions / SQL and see if the amount of IO can be reduced.Better approach will be to look at the sql query that need to be tuned and need to run in parallel .
Please check with ASH reports to see the all the queries which have this particular wait event .
Ensure no disks are IO bound.

And in the last , Please tune the disk_asynch_io and filesystemio_options parameters .

Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports

There will be  Significant Virtual Memory Paging on Linux When None is Occurring in ADDM Reports.

There may be following message in the ADDM report:

From  the ADDM report

FINDING 1: 100% impact (48628 seconds)
--------------------------------------
Significant virtual memory paging was detected on the host operating system.

RECOMMENDATION 1: Host Configuration, 100% benefit (32719 seconds)
ACTION: Host operating system was experiencing significant paging but
no particular root cause could be detected. Investigate processes that
do not belong to this instance running on the host that are
consuming significant amount of virtual memory. Also consider adding more
physical memory to the host.

First, review the following bugs which incorrectly show large swapping statistics that may cause incorrect ADDM message as per
above message.  And if applicable, apply the bugs.

For 10.2.0.5,  for Linux:

Note:12347332.8 Bug 12347332 - V$OSSTAT / ADDM incorrectly shows very large swapping/paging stats

This bug is specific to Linux.  So download the patch for Linux:
Patch:12347332

For 11.2, there is the following bug:      

Note:10220118.8 Bug 10220118 - Print warning to alert log when system is swapping

If available for your os, download following patch:
Patch:10220118