latch waits and what to do about them

System has been up and stable in OLTP from &AM to 12 Midinght and batch from midnight till 7 AM. However it seems like the latch waits are high. Latch waits go as high as 3875 System is stable but I always want more speed. (as long as it does not effect stability.) Here is onconfig I am running IBM Informix Dynamic Server Version 10.00.UC3 Workgroup Server on a HP dual processor Intel machine 8 Gig of memory Red Hat Enterprise Linux ES release 3 Kernel 2.4.21-47.ELsmp on an i686 onconfig looks like #************************************************************************** # # Licensed Material - Property Of IBM # # "Restricted Materials of IBM" # # IBM Informix Dynamic Server # (c) Copyright IBM Corporation 1996, 2005 All rights reserved. # # Title: onconfig.std # Description: IBM Informix Dynamic Server Configuration Parameters # #************************************************************************** # Root Dbspace Configuration ROOTNAME rootdbs # Root dbspace nameROOTPATH /dev/cciss/inforaw1 # Path for device containing root dbspace ROOTOFFSET 0 # Offset of root dbspace into device (Kbytes) ROOTSIZE 8000000 # Size of root dbspace (Kbytes) # 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 rootdbs # Location (dbspace) of physical log PHYSFILE 40000 # Physical log file size (Kbytes) # Logical Log Configuration LOGFILES 15 # Number of logical log files LOGSIZE 8000 # Logical log size (Kbytes)LOG_BACKUP_MODE CONT # Logical log backup mode (MANUAL, CONT) # Security # DBCREATE_PERMISSION: # By default any user can create a database. Uncomment DBCREATE_PERMISSON to # limit database creation to a specific user. Add a new DBCREATE_PERMISSION # line for each permitted user. #DBCREATE_PERMISSION informix # IFX_EXTEND_ROLE: # 0 => Disable use of EXTEND role to control who can register # external routines. This is the default behaviour. # 1 => Enable use of EXTEND role to control who can register # external routines. IFX_EXTEND_ROLE 0 # To control the usage of EXTEND role. # Tablespace Tablespace Configuration in Root Dbspace TBLTBLFIRST 0 # First extent size (Kbytes) (0 = default) TBLTBLNEXT 0 # Next extent size (Kbytes) (0 = default) # Diagnostics MSGPATH /informix10.0.uc3/online1204.log # System message log file path CONSOLE /dev/console # System console message path # To automatically backup logical logs, edit alarmprogram.sh and set # BACKUPLOGS=Y ALARMPROGRAM /informix10.0.uc3/etc/alarmprogram.sh # Alarm program path ALRM_ALL_EVENTS 0 # Triggers ALARMPROGRAM for any event occur TBLSPACE_STATS 1 # Maintain tblspace statistics # System Archive Tape Device TAPEDEV /dev/st0 # Tape device path #TAPEDEV /dev/null # Tape device path TAPEBLK 64 # Tape block size (Kbytes) TAPESIZE 47201280 # Maximum amount of data to put on tape (Kbytes) # Log Archive Tape Device #LTAPEDEV /dev/tapedev # Log tape device path LTAPEDEV /dev/null # Log tape device path LTAPEBLK 32 # Log tape block size (Kbytes) LTAPESIZE 10240 # Max amount of data to put on log tape (Kbytes) # Optical STAGEBLOB # Informix Dynamic Server staging area # System Configuration SERVERNUM 0 # Unique id corresponding to a OnLine instance DBSERVERNAME db3v124_shm # Name of default database server DBSERVERALIASES db3v124fast # List of alternate dbservernames DBSERVERALIASES db3v124link # List of alternate dbservernames NETTYPE soctcp,2,100,NET # Configure poll thread(s) for nettype NETTYPE ipcshm,1,250,CPU # Configure poll thread(s) for nettype DEADLOCK_TIMEOUT 600 # Max time to wait of lock in distributed env. 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 # If non-zero, limit number of cpu vps to one NOAGE 0 # Process aging AFF_SPROC 1 # Affinity start processor AFF_NPROCS 3 # Affinity number of processors # Shared Memory Parameters LOCKS 200000 # Maximum number of locks NUMAIOVPS 16 # Number of IO vps PHYSBUFF 128 # Physical log buffer size (Kbytes) LOGBUFF 64 # Logical log buffer size (Kbytes) CLEANERS 20 # Number of buffer cleaner processes SHMBASE 0x44000000L # Shared memory base address#SHMVIRTSIZE 8192 # initial virtual shared memory segment size SHMVIRTSIZE 131072 # initial virtual shared memory segment size SHMADD 32768 # Size of new shared memory segments (Kbytes)#SHMADD 64000 # Size of new shared memory segments (Kbytes) SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited CKPTINTVL 300 # Check point interval (in sec) TXTIMEOUT 300 # Transaction timeout (in sec)#TXTIMEOUT 60 # Transaction timeout (in sec) #STACKSIZE 32 # Stack size (Kbytes) STACKSIZE 128 # Stack size (Kbytes) # Dynamic Logging # DYNAMIC_LOGS: # 2 : server automatically add a new logical log when necessary. (ON) # 1 : notify DBA to add new logical logs when necessary. (ON) # 0 : cannot add logical log on the fly. (OFF) # # When dynamic logging is on, we can have higher values for LTXHWM/LTXEHWM, # because the server can add new logical logs during long transaction rollback. # However, to limit the number of new logical logs being added, LTXHWM/LTXEHWM # can be set to smaller values. # # If dynamic logging is off, LTXHWM/LTXEHWM need to be set to smaller values # to avoid long transaction rollback hanging the server due to lack of logical # log space, i.e. 50/60 or lower. # # In case of system configured with CDR, the difference between LTXHWM and # LTXEHWM should be atleast 30% so that we could minimize log overrun issue. DYNAMIC_LOGS 2 LTXHWM 70 LTXEHWM 80 # System Page Size # BUFFSIZE - OnLine no longer supports this configuration parameter. # To determine the page size used by OnLine on your platform # see the last line of output from the command, 'onstat -b'. # Recovery Variables # OFF_RECVRY_THREADS: # Number of parallel worker threads during fast recovery or an offline restore. # ON_RECVRY_THREADS: # Number of parallel worker threads during an online restore. 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 /informix10.0.uc3/etc/dr.lostfound # DR lost+found file path DRIDXAUTO 0 # DR automatic index repair. 0=off, 1=on # CDR Variables 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_NIFCOMPRESS 0 # Link level compression (-1 never, 0 none, 9 max) CDR_SERIAL 0 # Serial Column Seque

3,875 latch waits over the course of 23 hours? No worries mate. Do you have a reason to feel that your server is slow, other than the latch waits count? What do your metrics look like (BR, TR, RAU)? Recommendations in a vacuum? You have: NETTYPE ipcshm,1,250,CPU # Configure poll thread(s) for nettypeBut you have 3 CPU VPs. You should have a shared memory listener in every CPU VP unless those connections are ONLY used for administration. You have only 8 LRUs configured for your buffer pools, this MAY cause LRU contention if you have large numbers of users. Check your BR metric. You only have 256K of DS_TOTAL_MEMORY, this is used when PDQPRIORITY is non- zero for sorting and grouping and is especially important to index build and update statistics processing speed. Without PDQ the engine will use 15MB bedefault (and up to 50MB) for in-memory sorting. PDQ should have access to several times that if you have the memory available. Art S. Kagel ----- Original Message ----- From: Bill Marshall <ids@iiug.org> At: 7/06 6:56:22 System has been up and stable in OLTP from &AM to 12 Midinght and batch from midnight till 7 AM. However it seems like the latch waits are high. Latch waits go as high as 3875 System is stable but I always want more speed. (as long as it does not effect stability.) Here is onconfig I am running IBM Informix Dynamic Server Version 10.00.UC3 Workgroup Server on a HP dual processor Intel machine 8 Gig of memory Red Hat Enterprise Linux ES release 3 Kernel 2.4.21-47.ELsmp on an i686 onconfig looks like #************************************************************************** # # Licensed Material - Property Of IBM # # "Restricted Materials of IBM" # # IBM Informix Dynamic Server # (c) Copyright IBM Corporation 1996, 2005 All rights reserved. # # Title: onconfig.std # Description: IBM Informix Dynamic Server Configuration Parameters # #************************************************************************** # Root Dbspace Configuration ROOTNAME rootdbs # Root dbspace nameROOTPATH /dev/cciss/inforaw1 # Path for device containing root dbspace ROOTOFFSET 0 # Offset of root dbspace into device (Kbytes) ROOTSIZE 8000000 # Size of root dbspace (Kbytes) # 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 rootdbs # Location (dbspace) of physical log PHYSFILE 40000 # Physical log file size (Kbytes) # Logical Log Configuration LOGFILES 15 # Number of logical log files LOGSIZE 8000 # Logical log size (Kbytes)LOG_BACKUP_MODE CONT # Logical log backup mode (MANUAL, CONT) # Security # DBCREATE_PERMISSION: # By default any user can create a database. Uncomment DBCREATE_PERMISSON to # limit database creation to a specific user. Add a new DBCREATE_PERMISSION # line for each permitted user. #DBCREATE_PERMISSION informix # IFX_EXTEND_ROLE: # 0 => Disable use of EXTEND role to control who can register # external routines. This is the default behaviour. # 1 => Enable use of EXTEND role to control who can register # external routines. IFX_EXTEND_ROLE 0 # To control the usage of EXTEND role. # Tablespace Tablespace Configuration in Root Dbspace TBLTBLFIRST 0 # First extent size (Kbytes) (0 = default) TBLTBLNEXT 0 # Next extent size (Kbytes) (0 = default) # Diagnostics MSGPATH /informix10.0.uc3/online1204.log # System message log file path CONSOLE /dev/console # System console message path # To automatically backup logical logs, edit alarmprogram.sh and set # BACKUPLOGS=Y ALARMPROGRAM /informix10.0.uc3/etc/alarmprogram.sh # Alarm program path ALRM_ALL_EVENTS 0 # Triggers ALARMPROGRAM for any event occur TBLSPACE_STATS 1 # Maintain tblspace statistics # System Archive Tape Device TAPEDEV /dev/st0 # Tape device path #TAPEDEV /dev/null # Tape device path TAPEBLK 64 # Tape block size (Kbytes) TAPESIZE 47201280 # Maximum amount of data to put on tape (Kbytes) # Log Archive Tape Device #LTAPEDEV /dev/tapedev # Log tape device path LTAPEDEV /dev/null # Log tape device path LTAPEBLK 32 # Log tape block size (Kbytes) LTAPESIZE 10240 # Max amount of data to put on log tape (Kbytes) # Optical STAGEBLOB # Informix Dynamic Server staging area # System Configuration SERVERNUM 0 # Unique id corresponding to a OnLine instance DBSERVERNAME db3v124_shm # Name of default database server DBSERVERALIASES db3v124fast # List of alternate dbservernames DBSERVERALIASES db3v124link # List of alternate dbservernames NETTYPE soctcp,2,100,NET # Configure poll thread(s) for nettype NETTYPE ipcshm,1,250,CPU # Configure poll thread(s) for nettype DEADLOCK_TIMEOUT 600 # Max time to wait of lock in distributed env. 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 # If non-zero, limit number of cpu vps to one NOAGE 0 # Process aging AFF_SPROC 1 # Affinity start processor AFF_NPROCS 3 # Affinity number of processors # Shared Memory Parameters LOCKS 200000 # Maximum number of locks NUMAIOVPS 16 # Number of IO vps PHYSBUFF 128 # Physical log buffer size (Kbytes) LOGBUFF 64 # Logical log buffer size (Kbytes) CLEANERS 20 # Number of buffer cleaner processes SHMBASE 0x44000000L # Shared memory base address#SHMVIRTSIZE 8192 # initial virtual shared memory segment size SHMVIRTSIZE 131072 # initial virtual shared memory segment size SHMADD 32768 # Size of new shared memory segments (Kbytes)#SHMADD 64000 # Size of new shared memory segments (Kbytes) SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited CKPTINTVL 300 # Check point interval (in sec) TXTIMEOUT 300 # Transaction timeout (in sec)#TXTIMEOUT 60 # Transaction timeout (in sec) #STACKSIZE 32 # Stack size (Kbytes) STACKSIZE 128 # Stack size (Kbytes) # Dynamic Logging # DYNAMIC_LOGS: # 2 : server automatically add a new logical log when necessary. (ON) # 1 : notify DBA to add new logical logs when necessary. (ON) # 0 : cannot add logical log on the fly. (OFF) # # When dynamic logging is on, we can have higher values for LTXHWM/LTXEHWM, # because the server can add new logical logs during long transaction rollback. # However, to limit the number of new logical logs being added, LTXHWM/LTXEHWM # can be set to smaller values. # # If dynamic logging is off, LTXHWM/LTXEHWM need to be set to smaller values # to avoid long transaction rollback hanging the server due to lack of logical # log space, i.e. 50/60 or lower. # # In case of system configured with CDR, the difference between LTXHWM and # LTXEHWM should be atleast 30% so that we could minimize log overrun issue. DYNAMIC_LOGS 2 LTXHWM 70 LTXEHWM 80 # System Page Size # BUFFSIZE - OnLine no longer supports this configuration parameter. # To determine the page size used by OnLine on your platform@@