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  1. #1
    Join Date
    Jul 2003
    Posts
    11

    Unanswered: Problem with shared memory

    Iīm running an IDS 9.30 FC6 on a Solaris 8.
    When I try to make a backup with onbar the next message is shown:
    (onbar -b -w -L 0)

    shmdt: errno = 22

    If I view the shared memory I get:

    Shared Memory:
    m 0 0x50000a91 --rw-r--r-- root root 0
    m 8 0x5643 --rw-rw-rw- root other 0
    m 9 0x5654 --rw-rw-rw- root other 0
    m 4106 0x52564801 --rw-rw---- root informix 0
    m 4107 0x52564802 --rw-rw---- root informix 0
    m 4108 0x52564803 --rw-rw---- root informix 0
    m 3085 0x52564804 --rw-rw---- root informix 0
    m 3086 0x52564805 --rw-rw---- root informix 0
    m 3087 0x52564806 --rw-rw---- root informix 0
    m 3088 0x52564807 --rw-rw---- root informix 0
    m 3089 0x52564808 --rw-rw-rw- root informix 0

    And the parameters in onconfig.std are:

    # Shared Memory Parameters

    LOCKS 2000 # Maximum number of locks
    BUFFERS 5000 # Maximum number of shared buffers
    NUMAIOVPS # Number of IO vps
    PHYSBUFF 32 # Physical log buffer size (Kbytes)
    LOGBUFF 32 # Logical log buffer size (Kbytes)
    CLEANERS 1 # Number of buffer cleaner processes
    SHMBASE 0x10A000000L # Shared memory base address
    SHMVIRTSIZE 8000 # initial virtual shared memory segment size
    SHMADD 8192 # Size of new shared memory segments (Kbytes)
    SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited
    CKPTINTVL 300 # Check point interval (in sec)
    LRUS 8 # Number of LRU queues
    LRU_MAX_DIRTY 60 # LRU percent dirty begin cleaning limit
    LRU_MIN_DIRTY 50 # LRU percent dirty end cleaning limit
    TXTIMEOUT 300 # Transaction timeout (in sec)
    STACKSIZE 64 # Stack size (Kbytes)

    Does anyone know what can be happening?? Thanks!!!

  2. #2
    Join Date
    Jun 2003
    Location
    Hamburg, Germany
    Posts
    38
    I don't know, but I guess it's trying to create another shared mem segment but it can't. The error is generic and just means it found some system problem when it tried to grab a resource, like disk, memory, etc.
    What is your shared memory utilisation like? Ask a sysadmin or use one of the admin tools. You will probably need to increase some of the Solaris shm kernel parameters (take a look at informix admin guide).

  3. #3
    Join Date
    Jun 2003
    Location
    Hamburg, Germany
    Posts
    38
    PS: It looks like you also should change your SHMVRTSIZE to something like 65536 and set SHMADD to 32768 at the same time you change your kernel.
    You will see informix already grabbed successively more memory segments in your attachment - I guess if you look in your informix log file, they are created very soon after informix is restarted? So, why bother with creating several small segments, get only 1 and get something back that way. Increasing the SHMADD also means that informix doesn't need to add so many extra segments in future, if they are required.

  4. #4
    Join Date
    Aug 2002
    Location
    Belgium
    Posts
    534
    Could you post the output of 'onstat -g seg' ?
    rws

  5. #5
    Join Date
    Jul 2003
    Posts
    11
    Of course!!

    # onstat -g seg

    IBM Informix Dynamic Server Version 9.30.FC6 -- On-Line -- Up 00:03:57 -- 30720 Kbytes

    Segment Summary:
    id key addr size ovhd class blkused blkfree
    2050 1381386241 10a000000 12582912 419032 R 3026 46
    2051 1381386242 10ac00000 8388608 872 V 1774 274
    2052 1381386243 10b400000 9437184 904 V 2076 228
    1029 1381386244 10bd00000 1048576 648 M 135 121
    Total: - - 31457280 - - 7011 669

    (* segment locked in memory)

    Thanks!!!

  6. #6
    Join Date
    Aug 2002
    Location
    Belgium
    Posts
    534
    I think your problem is fully related to the kernel parameters.
    Check the /etc/system file with $INFORMIXDIR/release/en_us/0333/ids_machine_notes_9.30.txt

    Once you set it to the correct values, reboot the system for the changes to take effect.
    ALso make sure you follow the advise from AdiHH. You need to tune the parameters of you shared memory, depending of the total size of memory available.
    rws

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