Informix

Informix

Connect with Db2, Informix, Netezza, open source, and other data experts to gain value from your data, share insights, and solve problems.

 View Only

  • 1.  Static filenames for SAN partitions.

    Posted Tue February 11, 2020 04:41 AM
    Hi,
    We have a situation as follows :-
    1) The informix database server is running on a VM which is running on a RHEL hypervisor
    2) All the raw character devices for the informixserver is on SAN. These raw partitions on SAN is made available to the INFORMIXSERVER through the RHEL hypervisor (as per the SAN engineer as I don't know much about it).

    THE RSS database server was configured on this VM and it was running successfully. On a particular day, due to power loss (i.e. electricity outage), the RHEL Hypervisor along with ALL the VM sitting on it (which included the RSS databaseserver which was running on the VM), crashed. When power was restored. we started the RSS databaseserver with the command "oninit -v", but the RSS database server did not come up. it was complaining as follows :-
    ###########################
    15:25:51  I/O error, Primary Chunk '/usr/informix/data/d1' -- Offline (sanity)
    15:25:51  oninit: Fatal error in shared memory initialization
    ###########################
    The "/usr/informix/data/d1" is the "rootdbs" which is soft linked to the "/dev/raw/raw1"and /dev/raw/raw1" is a raw character device interface created from "/dev/sds" which is a  SAN partition.

    We checked up on SAN and found that ALL the device filenames from "/dev/sdb" to "dev/sds" which is assigned to the dbspaces/chunks of the RSS database server have been re-assigned (i.e. "/dev/sds" which was earlier pointing to a 600 MB "rootdbs" partition, is now pointing to a 100 GB "datadbs1" partition. Similarity, the /dev/sdq" SAN partition of 50 GB "tempdbs1" partition is now point to a different 100 GB which was originally a "datadbs2" partition. In short, ALL the filenames (i.e. /dev/sbd, /dev/sdc, /dev/sdd etc ...) of the SAN partition have been changed/re-assigned.

    Now, the SAN engineers have said that instead of creating soft links to the device filenames (i.e. /dev/sbd, /dev/sdc, /dev/sdd etc ...), create a soft links to the SAN device partition "/dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000". But I have found that the SAN device filename i.e. "/dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000" is a soft link file by itself for the actual SAN partition "/dev/sdh" as follows :- 
    $ ls -l /dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000
    lrwxrwxrwx. 1 root root 9 Feb 10 12:49 /dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000 -> ../../sdh
    [informix@drinfdb101 ~]$ ls -l /dev/sdh
    brw-rw----. 1 root disk 8, 112 Feb 10 12:49 /dev/sdh


    My question is :-
    1) should I use the "/dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000" for creation of "raw" device interface for the RSS database server and proceed ? Also, 2) can a "raw" character interface be created from a soft -link file name


    Thanks & Regards,
    Neville Monteiro.

    Sent with ProtonMail Secure Email.


    #Informix


  • 2.  RE: Static filenames for SAN partitions.

    Posted Tue February 11, 2020 09:37 AM

    2) can a "raw" character interface be created from a soft -link file name

    yes:

    lrwxrwxrwx. 1 root root 9 Oct 6 12:50 scsi-35f8db4c461706811 -> ../../sdd

    ls -lL /dev/disk/by-id/scsi-35f8db4c461706811

    brw-rw----. 1 root disk 8, 48 Oct 6 12:50 /dev/disk/by-id/scsi-35f8db4c461706811

    raw /dev/raw/raw1 /dev/disk/by-id/scsi-35f8db4c461706811


    /dev/raw/raw1: bound to major 8, minor 48

    1) should I use the "/dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000" for creation of "raw" device interface for the RSS database server and proceed ?

    If these identifiers don't change across reboot - why not?  One potential issue - if the "disk" is "replaced" these will definitely change.



    ------------------------------
    Vladimir Kolobrodov
    ------------------------------

    Original Message


  • 3.  RE: Static filenames for SAN partitions.

    Posted Tue February 11, 2020 12:46 PM
    Edited by System Admin Fri January 20, 2023 04:19 PM
    Hello Neville,

    The file "/dev/disk/by-id/scsi-3600c0ff000130d170edb315e01000000" points to a block device and should not be used in Informix.
    If the files such as sdb and sdc change each time the server is rebooted, you should look at the raw device mapping settings.
    And when rebooting, the permissions of the raw device files used by Informix should be set to 660 and the owner and group to informix.

    ------------------------------
    SangGyu Jeong
    Software Engineer
    Infrasoft
    Seoul Korea, Republic of
    ------------------------------

    Original Message


Related Content