IDS Forum

long checkpoints

Posted By: Egan Karen-kegan01
Date: Tuesday, 28 September 2004, at 9:49 a.m.

Hi all,

the performance on one of our Customer's production databases has decreased dramatically in the last couple of weeks. Checkpoints seem to be taking over a minute to complete. Running IDS 9.21 UC6 (which I know is no longer supported but unfortunately as it is out there in our product in the field I can't do much about this) on Solaris 8.

If anyone has any pointers on the config parameters below that may help to improve performance they would be greatly appreciated. Also are there any know bugs with checkpoints on this version of Informix.

Below are what I believe are the relevant onconfig parameters

PHYSDBS omc_db_plog # Location (dbspace) of physical log
PHYSFILE 253894 # Physical log file size (Kbytes)

LOGFILES 3 # Number of logical log files
LOGSIZE 2000 # Logical log size (Kbytes)

NOFUZZYCKPT 1 # No fuzzy checkpoints


MULTIPROCESSOR 1 # 0 for single-processor, 1 for multi-processor
NUMCPUVPS 2 # Number of user (cpu) vps
SINGLE_CPU_VP 0 # If non-zero, limit number of cpu vps to one


# Shared Memory Parameters
LOCKS 75000 # Maximum number of locks
BUFFERS 50000 # Maximum number of shared buffers
NUMAIOVPS 1 # Number of IO vps
PHYSBUFF 128 # Physical log buffer size (Kbytes)
LOGBUFF 128 # Logical log buffer size (Kbytes)
LOGSMAX 50 # Maximum number of logical log files
CLEANERS 6 # Number of buffer cleaner processes
SHMBASE 0xa000000 # Shared memory base address
SHMVIRTSIZE 32000 # 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 15 # Number of LRU queues
LRU_MAX_DIRTY 2 # LRU percent dirty begin cleaning limit
LRU_MIN_DIRTY 1 # 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)
RA_PAGES 32 # Number of pages to attempt to read ahead
RA_THRESHOLD 28 # Number of pages left before next group
DBSPACETEMP omc_db_temp # Default temp dbspaces

output from onstat -p

Profile
dskreads pagreads bufreads Êched dskwrits pagwrits bufwrits Êched
890960 1087371 36156569 97.54 851638 1850908 3389826 74.88

isamtot open start read write rewrite delete commit rollbk
27502723 47701 2493635 17606895 857421 17010 300250 823 0

gp_read gp_write gp_rewrt gp_del gp_alloc gp_free gp_curs
0 0 0 0 0 0 0

ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes
0 0 0 2598.48 409.81 84 196

bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans
164589 93 18694337 0 0 88 42716 5906

ixda-RA idx-RA da-RA RA-pgsused lchwaits
271575 11542 14060 292760 6173

onstat -m

Informix Dynamic Server 2000 Version 9.21.UC6 -- On-Line -- Up 08:16:55 -- 147456 Kbytes

Message Log File: /usr/informix/online.log_OMC
<<Informix Dynamic Server 2000>>> Logical Log 12764 Complete.
01:50:59 Logical Log 12764 Complete.
01:53:23 Checkpoint Completed: duration was 97 seconds.
01:53:23 Checkpoint loguniq 12765, logpos 0x2af3d4

01:59:59 Checkpoint Completed: duration was 95 seconds.
01:59:59 Checkpoint loguniq 12765, logpos 0x14df54c

02:06:04 Checkpoint Completed: duration was 66 seconds.
02:06:04 Checkpoint loguniq 12765, logpos 0x2595418


<<Informix Dynamic Server 2000>>> Logical Log 12765 Complete.
02:10:10 Logical Log 12765 Complete.
02:12:06 Checkpoint Completed: duration was 62 seconds.
02:12:06 Checkpoint loguniq 12766, logpos 0x3bc418

02:18:16 Checkpoint Completed: duration was 70 seconds.
02:18:16 Checkpoint loguniq 12766, logpos 0x1676018

Messages In This Thread

• long checkpoints
  Egan Karen-kegan01 -- Tuesday, 28 September 2004, at 9:49 a.m.
  • Re: long checkpoints
    jspalla@anexsys.com -- Tuesday, 28 September 2004, at 12:10 p.m.
  • RE: long checkpoints
    Alexey Sonkin -- Thursday, 28 October 2004, at 1:28 p.m.
    • RE: long checkpoints
      Darrell Murphy -- Thursday, 28 October 2004, at 2:46 p.m.
      • RE: long checkpoints
        Esteban Casuscelli -- Thursday, 28 October 2004, at 6:13 p.m.

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