SINGLE CLIENT ACCESS NAME (SCAN) by Barb Lundhild, Markus Michalewicz

The best paper about Oracle SCAN writing until today.

SINGLE CLIENT ACCESS NAME (SCAN) by Barb Lundhild, Markus Michalewicz



4 Comments on “SINGLE CLIENT ACCESS NAME (SCAN) by Barb Lundhild, Markus Michalewicz”

  1. Kabbo says:

    Hi Barb,

    I recently read your paper “SINGLE CLIENT ACCESS NAME (SCAN)” online, since I needed one precisely. Let me tell you where I am stuck, and I can’t seem to find a solution from anywhere, including Oracle documentations.

    This is just a small educational project that I do at my home system in order to get my certification in OCM, since I am a laid off employee from Oracle and cannot afford to pay more $5000 in order to get the training.

    I have two servers with OEL5 update 5 with x64 bit architecture. Each one has 8GB of RAM, two Gigabit NIC cards, and I am setting RAC on these two nodes using Grid Infrastructure. I have a router in between my servers and my ISP. When I tried to install Grid Infrastructure, after running the on node one which said that the configuration of Grid Infrastructure was successful, I got the following error on the second node when I ran the on it:

    PRCR-1079 : Failed to start resource ora.gns
    CRS-5005: IP Address: is already in use in the network
    CRS-2674: Start of ‘’ on ‘host02’ failed
    CRS-2632: There are no more servers to try to place resource ‘ora.gns’ on that would satisfy its placement policy
    start gns … failed

    During the installation of Grid infrastructure, I selected :
    1. Configure GNS
    2. GNS Subdomain: host-cluster-scan.localdomain
    3. GNS VIP Address: < —————– This IP is not assigned to any machine in my local network yet.

    The IPs that got picked up for my NICs, eth0 and eth1, were and, respectively.

    During the run of in node one the IP address,, was configured as one of the VIP’s address as below:

    eth0:1 Link encap:Ethernet HWaddr 00:1E:E5:D6:D2:05
    inet addr: Bcast: Mask:
    Interrupt:22 Base address:0x8800

    When I ran the “” on the second node, that is where I got the error above while running And as a result, the configuration of Grid Infrastructure as well as the cluster verification check failed. Then I tried to install RAC database software to see if I could still install the database piece, I was only able to see node one in the “ node selection screen”. By the way I used ASM for my OCR and Voting disk. Now, here are my questions:

    In your document about SCAN, you mentioned that as long as you have DHCP setup through your public network, VIPs will get assigned by GNS during installation. Well, I do have DHCP running, and I also have DNS addresses in my “ /etc/resolv.conf “ file , like so:

    [grid@host01 deinstall]$ cat /etc/resolv.conf
    ; generated by /sbin/dhclient-script
    nameserver 76.xx.x.x
    nameserver 76.xx.x.x

    No matter what IP I choose for the “GNS VIP Address”, this IP address get looked up by Oracle during the run of for the second node, and sicne it has already been assigned to one of the VIPs for node one, and is no longer available, the configuration ora.gns fails on the second node. And this has become a show stopper for me. I am not sure if this is a bug and has been fixed in or not, but I can’t say. Would you please let me know since you are saying in your document that this is supposed to work?

    I would truly appreciate if you provide to me with an explanation of what is going on here and what am I doing incorrectly. Again, I do not have any entries concerning the GNS and DNS in the resolv.conf file or any where in the server. Since this is my home system, I cannot setup the DNS, but all I could get from my ISP is the address of the DNS servers which is in my /etc/resolv.conf file.

    P.S. Can you please respond to me in my email


  2. Markus says:

    Hi Levi,

    Thank you for the update and the link.

    — Markus


  3. […] 0 Times in 0 Posts Hi, I recommend you read this white paper.. SINGLE CLIENT ACCESS NAME (SCAN) by Barb Lundhild, Markus Michalewicz Regards, Reply With […]


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