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11 Replies Latest reply: Oct 31, 2013 6:44 AM by Levi-Pereira RSS

How to choose scan ip for scan listener?

Lonion Newbie
Currently Being Moderated

Background Description:

 

Assume

 

I have a 11gR2 RAC with 3 nodes. If I configure 4 scan ip resolved by DNS, which three scan ip would be choosen for scan listener? Does it like below?

 

4 scan ip in DNS server:

192.168.2.101

192.168.2.102

192.168.2.103

192.168.2.104

 

The scan listener's ip may be like below:

node1
[grid@rac1 ~]$ lsnrctl status listener_scan1
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.101)(PORT=1521)))
node2
[grid@rac2 ~]$ lsnrctl status listener_scan2
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN2)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.102)(PORT=1521)))
node3
[grid@rac3 ~]$ lsnrctl status listener_scan3
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN3)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.103)(PORT=1521)))

 

 

But it also can be choosen like below

node1
[grid@rac1 ~]$ lsnrctl status listener_scan1
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.103)(PORT=1521)))
node2
[grid@rac2 ~]$ lsnrctl status listener_scan2
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN2)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.102)(PORT=1521)))
node3
[grid@rac3 ~]$ lsnrctl status listener_scan3
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN3)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.104)(PORT=1521)))

 

and so on .

 

Above is my guess, so what's the real combination of three ip ?

 

Pls help me.

  • 1. Re: How to choose scan ip for scan listener?
    Svetoslav Gyurov Explorer
    Currently Being Moderated

    Hi Lonion,

     

    First of all the SCAN need only three IP addresses and not four. Before installation SCAN hostname is configured in the DNS to resolve to three ip addresses (mycluster-scan). Upon installation the installer will resolve these three ip addresses and assign them to the scan vips THE WAY their are returned by the DNS at that point. Because DNS works in round robin fashion you can't say what would be the combination until the time the installation finish.

     

    Once the SCAN VIPs are assigned, the SCAN LISTENERs will run on top of the VIPs to provide access for the clients.

     

    Regards,

    Sve

     

    p.s. Having four IP addresses for the scan would result that one in four users will get timeout.

  • 2. Re: How to choose scan ip for scan listener?
    Lonion Newbie
    Currently Being Moderated

    Hi, SvetoslavGyurov. Pls look at my real RAC environment.

     

    [grid@rac1 ~]$ srvctl status scan_listener

    SCAN Listener LISTENER_SCAN1 is enabled

    SCAN listener LISTENER_SCAN1 is running on node rac1

    SCAN Listener LISTENER_SCAN2 is enabled

    SCAN listener LISTENER_SCAN2 is running on node rac3

    SCAN Listener LISTENER_SCAN3 is enabled

    SCAN listener LISTENER_SCAN3 is running on node rac2

    SCAN Listener LISTENER_SCAN4 is enabled

    SCAN listener LISTENER_SCAN4 is running on node rac4

    [grid@rac1 ~]$

    [grid@rac1 ~]$ srvctl config scan

    SCAN name: rac, Network: 1/192.168.2.0/255.255.255.0/eth0

    SCAN VIP name: scan1, IP: /rac/192.168.2.177

    SCAN VIP name: scan2, IP: /rac/192.168.2.178

    SCAN VIP name: scan3, IP: /rac/192.168.2.179

    SCAN VIP name: scan4, IP: /rac/192.168.2.180

     

    Node 1

    [grid@rac1 ~]$ lsnrctl status listener_scan1
    LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 22-OCT-2013 17:02:47
    Copyright (c) 1991, 2011, Oracle.  All rights reserved.
    Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1)))
    STATUS of the LISTENER
    ------------------------
    Alias                     LISTENER_SCAN1
    Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
    Start Date                24-SEP-2013 14:24:11
    Uptime                    28 days 2 hr. 38 min. 36 sec
    Trace Level               off
    Security                  ON: Local OS Authentication
    SNMP                      OFF
    Listener Parameter File   /u01/app/grid/network/admin/listener.ora
    Listener Log File         /u01/app/grid/log/diag/tnslsnr/rac1/listener_scan1/alert/log.xml
    Listening Endpoints Summary...
      (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN1)))
      (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.177)(PORT=1521)))
    Services Summary...
    Service "abc" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    Service "abcXDB" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    The command completed successfully
    [grid@rac1 ~]$ 

     

     

    Node 2

    [grid@rac1 ~]$ ssh rac2
    Last login: Mon Oct 21 16:28:55 2013 from rac1
    [grid@rac2 ~]$ 
    [grid@rac2 ~]$ lsnrctl status listener_scan3
    LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 22-OCT-2013 17:04:13
    Copyright (c) 1991, 2011, Oracle.  All rights reserved.
    Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN3)))
    STATUS of the LISTENER
    ------------------------
    Alias                     LISTENER_SCAN3
    Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
    Start Date                18-SEP-2013 13:59:43
    Uptime                    34 days 3 hr. 4 min. 30 sec
    Trace Level               off
    Security                  ON: Local OS Authentication
    SNMP                      OFF
    Listener Parameter File   /u01/app/grid/network/admin/listener.ora
    Listener Log File         /u01/app/grid/log/diag/tnslsnr/rac2/listener_scan3/alert/log.xml
    Listening Endpoints Summary...
      (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN3)))
      (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.179)(PORT=1521)))
    Services Summary...
    Service "abc" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    Service "abcXDB" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    The command completed successfully
    [grid@rac2 ~]$ 

     

     

    Node 3

    [grid@rac2 ~]$ ssh rac3
    Last login: Mon Oct 21 16:29:41 2013 from rac2
    [grid@rac3 ~]$ lsnrctl status listener_scan2
    LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 22-OCT-2013 17:04:52
    Copyright (c) 1991, 2011, Oracle.  All rights reserved.
    Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN2)))
    STATUS of the LISTENER
    ------------------------
    Alias                     LISTENER_SCAN2
    Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
    Start Date                24-SEP-2013 14:19:31
    Uptime                    28 days 2 hr. 45 min. 20 sec
    Trace Level               off
    Security                  ON: Local OS Authentication
    SNMP                      OFF
    Listener Parameter File   /u01/app/grid/network/admin/listener.ora
    Listener Log File         /u01/app/grid/log/diag/tnslsnr/rac3/listener_scan2/alert/log.xml
    Listening Endpoints Summary...
      (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN2)))
      (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.178)(PORT=1521)))
    Services Summary...
    Service "abc" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    Service "abcXDB" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    The command completed successfully
    [grid@rac3 ~]$ 

     

     

    Node 4

    [grid@rac3 ~]$ ssh rac4
    Last login: Mon Oct 21 16:30:24 2013 from rac3
    [grid@rac4 ~]$ 
    [grid@rac4 ~]$ lsnrctl status listener_scan4
    LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 22-OCT-2013 17:05:28
    Copyright (c) 1991, 2011, Oracle.  All rights reserved.
    Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN4)))
    STATUS of the LISTENER
    ------------------------
    Alias                     LISTENER_SCAN4
    Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
    Start Date                18-SEP-2013 13:59:43
    Uptime                    34 days 3 hr. 5 min. 44 sec
    Trace Level               off
    Security                  ON: Local OS Authentication
    SNMP                      OFF
    Listener Parameter File   /u01/app/grid/network/admin/listener.ora
    Listener Log File         /u01/app/grid/log/diag/tnslsnr/rac4/listener_scan4/alert/log.xml
    Listening Endpoints Summary...
      (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER_SCAN4)))
      (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=192.168.2.180)(PORT=1521)))
    Services Summary...
    Service "abc" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    Service "abcXDB" has 4 instance(s).
      Instance "abc1", status READY, has 1 handler(s) for this service...
      Instance "abc2", status READY, has 1 handler(s) for this service...
      Instance "abc3", status READY, has 1 handler(s) for this service...
      Instance "abc4", status READY, has 1 handler(s) for this service...
    The command completed successfully
    [grid@rac4 ~]$ 

     

     

    Look, there are 4 scan ip in my 11gR2 RAC environment. So, I think your opinion First of all the SCAN need only three IP addresses and not four」 is wrong.

  • 3. Re: How to choose scan ip for scan listener?
    FreddieEssex Pro
    Currently Being Moderated

    Hi,

     

    Oracle document states the following:

     

    Oracle RAC 11g release 2 (11.2) introduces the Single Client Access Name (SCAN). SCAN is a domain name registered to at least one and up to three IP addresses, either in DNS or GNS.

     

    Configure up to three SCAN addresses for the entire cluster.

    Introduction to Oracle Clusterware

     

    However, from your output it looks like all 4 SCAN addresses have been configured in both DNS and SCAN, but you are getting different IP's assigned to each scan listener when you run a lsnrctl status scan_listenerx due to round robin.  I suspect this anomaly is due to you having assigned 4 IP's in DNS.

     

    Even for a 20 node cluster you only need 3 SCAN addresses, so the fact remains.  Although you have proved that you can configure more than 3 addresses for SCAN (albeit with the unwanted affect as described), you only need 3 SCAN addresses.  Furthermore, Oracle documentation itself states that you should only configure up to 3 addresses for SCAN.

  • 4. Re: How to choose scan ip for scan listener?
    Levi-Pereira Guru
    Currently Being Moderated

    Hi,

    Rule: All IP assigned to SCAN Hostname in DNS must be configured on Clusterware as SCAN IP/Listener.

    3 SCAN IP is recommended, but you can have more than 3 SCAN IP.

    Usually 3 SCAN IP is enough need and you don't need to setup a SCAN IP for each hostname, the purpose of SCAN is quite different from the VIP/Local Listener.

  • 5. Re: How to choose scan ip for scan listener?
    Lonion Newbie
    Currently Being Moderated

    Rule: All IP assigned to SCAN Hostname in DNS must be configured on Clusterware as SCAN IP/Listener.

    Hi, I have 2 questions about this as follow:

    1. Which document this opinion quote from?

    2. If I conigured 4 IP in DNS, but only 3 nodes in my RAC environment, which 3 IP would be choosen for the scan listeners?

  • 6. Re: How to choose scan ip for scan listener?
    Lonion Newbie
    Currently Being Moderated

    Nobody can answer me?

    so sad,  T  _T ........

  • 7. Re: How to choose scan ip for scan listener?
    MahirM.Quluzade Guru
    Currently Being Moderated

    Lonion wrote:

     

    Rule: All IP assigned to SCAN Hostname in DNS must be configured on Clusterware as SCAN IP/Listener.

    Hi, I have 2 questions about this as follow:

    1. Which document this opinion quote from?

    2. If I conigured 4 IP in DNS, but only 3 nodes in my RAC environment, which 3 IP would be choosen for the scan listeners?

    Hi,

     

    I think your questions answered before replies.

     

    1. Please check : Typical Installation for Oracle Grid Infrastructure for a Cluster  - 1.3.2.2 IP Address Requirements

    2. Three Static IP addresses configured on the domain name server (DNS) before installation so that the three IP addresses are associated with the name provided as the SCAN, and all three addresses are returned in random order by the DNS to the requestor.

     

    Regards

    Mahir M. Quluzade

  • 8. Re: How to choose scan ip for scan listener?
    Lonion Newbie
    Currently Being Moderated

    Hi, MahirM.Quluzade:

    You may mistake me regarding the second question. The important point is 4 ip (for example,ip1,ip2,ip3,ip4) corresponding 3 node, then which three ip would be choosen from the 4 ip as the scan listener's ip? 「ip1,ip2,ip3」 or 「ip1,ip3,ip4」 or 「ip2,ip3,ip4」 and so on?

     

    God bless that you can understand me.

  • 9. Re: How to choose scan ip for scan listener?
    MahirM.Quluzade Guru
    Currently Being Moderated

    Hi,

     

    I understand your question

    I' not sure, which combination will choose for SCAN listeners.

     

    You can check with  nslookup  <scan-name>

     

    But i'm sure you must use 3 IPs for SCAN names.

    It is not difficult  delete 4th IP  from  DNS. May be need restart cluster.

     

    Regards

    Mahir M. Quluzade

  • 10. Re: How to choose scan ip for scan listener?
    FreddieEssex Pro
    Currently Being Moderated

    Yes, I agree...you are sad.

     

    Try google...it's amazing what you find on there

  • 11. Re: How to choose scan ip for scan listener?
    Levi-Pereira Guru
    Currently Being Moderated

    Hi,

    You are trying to do something not recommended by Oracle.

    Then to get answers to these questions you can issue a SR to MoS.

     

    My answer is : Follow exactly what is written in these docs.

     

    http://www.oracle.com/technetwork/products/clustering/overview/scan-129069.pdf

    Grid Infrastructure Single Client Access Name (SCAN) Explained (Doc ID 887522.1)

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