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  1. #1
    Join Date
    Sep 2002
    Posts
    12

    Post Unanswered: Our Checkpoint duration time is too long

    our average checkpoint duration time in Informýx Online 7.31 is 9-10 seconds. Do you think it is normal? What can be done to tune it to normal duration times(say less than 5 minutes)?

    our configuration file;

    BUFFERS 400000
    PHYSBUFF 1024
    LOGBUFF 128
    CLEANERS 128
    PHYSFILE 490000
    LOGFILES 80
    LOGSIZE 25000
    LRU_MAX_DIRTY 3 #(%)
    LRU_MAX_DIRTY 2 #(%)

    with checkpoint time 3 minutes.

    Platform:
    HP-UX B.11.00 U 9000/800

    Thanks in advance.

  2. #2
    Join Date
    Aug 2002
    Location
    Belgium
    Posts
    534
    Now, you forgot a very important parameter: How many LRU queues do you have?
    rws

  3. #3
    Join Date
    Sep 2002
    Posts
    12

    Our Checkpoint duration time is too long

    LRU 127

  4. #4
    Join Date
    Aug 2002
    Location
    Belgium
    Posts
    534
    Than the only thing you can do is:
    LRU_MAX_DIRTY 2
    LRU_MIN_DIRTY 1

    You can always decrease the amount of BUFFERS. Or move some data around. Check with 'onstat -D', 'onstat -g ioq', 'onstat -g iof' what dbspaces cause the long checkpoints.

    Check with sysmaster:sysptprof which tables are heavily accessed. Try fragmentation on the bigger tables....
    rws

  5. #5
    Join Date
    Sep 2002
    Posts
    12

    Our Checkpoint duration time is too long

    Mr. Roelwe here is our onconfig file:

    Configuration File: /data_1/informix/etc/onconfig
    #************************************************* *************************
    #
    # INFORMIX SOFTWARE, INC.
    #
    # Title: onconfig.std
    # Description: Informix Dynamic Server Configuration Parameters
    #
    #************************************************* *************************

    # Root Dbspace Configuration

    ROOTNAME rootdbs # Root dbspace name
    ROOTPATH /data_1/IFMXDATA/phydev4/chunk4_1 #19.11.2000 chunk4_3 idi
    ROOTOFFSET 100 # Offset of root dbspace into device (Kbytes)
    ROOTSIZE 999900

    # Disk Mirroring Configuration Parameters

    MIRROR 0 # Mirroring flag (Yes = 1, No = 0)
    MIRRORPATH # Path for device containing mirrored root
    MIRROROFFSET 0 # Offset into mirrored device (Kbytes)

    # Physical Log Configuration

    PHYSDBS plogdbs # Location (dbspace) of physical log
    PHYSFILE 490000 # Physical log file size (Kbytes)

    # Logical Log Configuration

    LOGFILES 80 # Number of logical log files
    LOGSIZE 25000 # Logical log size (Kbytes)


    RESIDENT 1 # Forced residency flag (Yes = 1, No = 0)

    MULTIPROCESSOR 1 # 0 for single-processor, 1 for multi-processor
    NUMCPUVPS 3 # Number of user (cpu) vps
    SINGLE_CPU_VP 0

    NOAGE 0 # Process aging
    AFF_SPROC 0 # Affinity start processor
    AFF_NPROCS 0 # Affinity number of processors

    # Shared Memory Parameters

    LOCKS 500000

    BUFFERS 460000 # Maximum number of shared buffers
    NUMAIOVPS 40 # Number of IO vps
    PHYSBUFF 1024 # Physical log buffer size (Kbytes)
    LOGBUFF 128 # Logical log buffer size (Kbytes)
    LOGSMAX 120 # Maximum number of logical log files
    CLEANERS 127 # Number of buffer cleaner processes
    #CLEANERS 4 # Number of buffer cleaner processes
    SHMBASE 0x0 # Shared memory base address
    SHMVIRTSIZE 1100000 # initial virtual shared memory segment size
    SHMADD 64000 # Size of new shared memory segments (Kbytes)
    SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited
    CKPTINTVL 180 #300 # Check point interval (in sec)
    LRUS 127 # 512 #127 # Number of LRU queues
    LRU_MAX_DIRTY 2 #10 # LRU percent dirty begin cleaning limit
    LRU_MIN_DIRTY 1 #5 # LRU percent dirty end cleaning limit
    LTXHWM 50 # Long transaction high water mark percentage
    LTXEHWM 60 # Long transaction high water mark (exclusive)
    TXTIMEOUT 0x12c # Transaction timeout (in sec)
    STACKSIZE 32 # Stack size (Kbytes)


    OFF_RECVRY_THREADS 10 # Default number of offline worker threads
    ON_RECVRY_THREADS 1 # Default number of online worker threads

    # Data Replication Variables
    # DRAUTO: 0 manual, 1 retain type, 2 reverse type
    DRAUTO 0 # DR automatic switchover
    DRINTERVAL 30 # DR max time between DR buffer flushes (in sec)
    DRTIMEOUT 30 # DR network timeout (in sec)
    DRLOSTFOUND /usr/informix/etc/dr.lostfound # DR lost+found file path

    # CDR Variables
    CDR_LOGBUFFERS 2048 # size of log reading buffer pool (Kbytes)
    CDR_EVALTHREADS 1,2 # evaluator threads (per-cpu-vp,additional)
    CDR_DSLOCKWAIT 5 # DS lockwait timeout (seconds)
    CDR_QUEUEMEM 4096 # Maximum amount of memory for any CDR queue (Kbytes)
    CDR_LOGDELTA 30 # % of log space allowed in queue memory
    CDR_NUMCONNECT 16 # Expected connections per server
    CDR_NIFRETRY 300 # Connection retry (seconds)
    CDR_NIFCOMPRESS 0 # Link level compression (-1 never, 0 none, 9 max)
    DBSPACETEMP tempdbs # Default temp dbspaces


    FILLFACTOR 90 # Fill factor for building indexes

    # method for Dynamic Server to use when determining current time
    USEOSTIME 0 # 0: use internal time(fast), 1: get time from OS(slow)

    # Parallel Database Queries (pdq)
    MAX_PDQPRIORITY 100 # Maximum allowed pdqpriority
    DS_MAX_QUERIES # Maximum number of decision support queries
    DS_TOTAL_MEMORY # Decision support memory (Kbytes)
    DS_MAX_SCANS 1048576 # Maximum number of decision support scans
    DATASKIP off # List of dbspaces to skip

    Thanks in advance.

  6. #6
    Join Date
    Aug 2002
    Location
    Belgium
    Posts
    534
    Config looks ok to me.
    How many processors are in the machine?
    How many chunks do you have?

    I really think the long checkpoint duration can be due to the disks that cannot follow.
    onstat -g ioq
    shows the queue per chunk. This maxlen parameter should not exceed 25.
    rws

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