Re: Q about LatchWaits, BufWaits and LRU-Writes
Hi,
Don't let the actual number of bufwaits concern you. What is important is
the RATIO of bufwaits to pages used. In your case this is about 1.4% which
is great.
The reason why you are not doing alot of LRU writing is because your probably
not hitting the 1% that you have set fro LRU_MAX_DIRTY. Since you now
have approx. 400 MB of actual buffer space (assuming a 2KB page size)
this means that you'll need 4MB of dirty pages before the page cleaners
will consider cleaning anything between checkpoints. What is your checkpoint
duration? You've got lots of LRU's - why not as many CLEANERS?
-Bill
}
} Hello out there,
}
} some weeks ago we've big performance problems on a HP K200 (2 processors) with
} HP-UX 10.01 and a RAID5-DiskArray and INFORMIX 7.13.UC3. With the help of this
} newsgroup, I've found out that we need more memory. So we've made an upgrade
} from 512 MB to 1 GB of memory and I've increased the BUFFERS from 40000 to
} 200000. Now the performance is ok. But I wonder why the values of LatchWaits
} and BufWaits are constantly growing and if this have still negative affects on
} performance.
}
} Furthermore I've some problems with LRU-Writes. Although I've set the
} number of LRUs to 96 and LRU_MAX_DIRTY to 1 and LRU_MIN_DIRTY to 0 the
} LRU-Writes are very low (2533 LRU-Writes vs. 146712 Chunk-Writes). Can anybody
} explain this to me?
}
} Any hints are welcome. Thanks in advance...
}
} Dirk
}
}
} Here is the output of "onstat -p":
} ----------------------------------
}
} INFORMIX-OnLine Version 7.13.UC3 -- On-Line -- Up 7 days 05:49:30 -- 502000
} Kbytes
}
} Profile
} dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached
} 37331331 115303579 667158188 94.40 237750 621756 1193917 80.09
}
} isamtot open start read write rewrite delete commit rollbk
} 349529853 21045964 29129981 264155205 403999 192019 33746 86182 3670
}
} ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes
} 0 0 0 113415.50 14806.18 761 4122
}
} bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans
} 1646133 252 664245233 1 0 557 16476 1092192
}
} ixda-RA idx-RA da-RA RA-pgsused lchwaits
} 17973866 7707 12755730 30627909 268121
}
}
} Here is the output of "onstat -F | head":
} -----------------------------------------
}
} INFORMIX-OnLine Version 7.13.UC3 -- On-Line -- Up 7 days 05:51:42 -- 502000
} Kbytes
}
} Fg Writes LRU Writes Chunk Writes
} 0 2533 146712
}
} address flusher state data
} c0c92444 0 I 0 = 0X0
} c0c92878 1 I 0 = 0X0
} c0c92cac 2 I 0 = 0X0
}
}
} Here is my ONCONFIG file:
} -------------------------
}
} #**************************************************************************
} #
} # INFORMIX SOFTWARE, INC.
} #
} # Title: onconfig.prod
} # Description: INFORMIX-OnLine Configuration Parameters
} #
} #**************************************************************************
}
} # Root Dbspace Configuration
}
} ROOTNAME rootdbs # Root dbspace name
} ROOTPATH /dev/onkommunal.root1 # Path for device containing root
} dbspace
} ROOTOFFSET 0 # Offset of root dbspace into device (Kbytes)
} ROOTSIZE 2088960 # 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 1310720 # Physical log file size (Kbytes)
}
} # Logical Log Configuration
}
} LOGFILES 30 # Number of logical log files
} LOGSIZE 10500 # Logical log size (Kbytes)
}
} # Diagnostics
}
} MSGPATH /opt/profiskal/informix7/log/online.komu
} # System message log file path
} CONSOLE /dev/console # System console message path
} ALARMPROGRAM /usr/local/bin/informixalarm # Alarm program path
}
} # System Archive Tape Device
}
} TAPEDEV /dev/rmt/1m # Tape device path
} TAPEBLK 16 # Tape block size (Kbytes)
} TAPESIZE 50331648 # Maximum amount of data to put on tape
} (Kbytes)
}
} # Log Archive Tape Device
}
} LTAPEDEV /dev/null # Log tape device path
} LTAPEBLK 16 # Log tape block size (Kbytes)
} LTAPESIZE 10240 # Max amount of data to put on log tape
} (Kbytes)
}
} # Optical
}
} STAGEBLOB # INFORMIX-OnLine/Optical staging area
}
} # System Configuration
}
} SERVERNUM 2 # Unique id corresponding to a OnLine instance
} DBSERVERNAME kommunalecht # Name of default database server
} DBSERVERALIASES amt10h02komu # List of alternate dbservernames
} DEADLOCK_TIMEOUT 60 # Max time to wait of lock in distributed
} env.
} RESIDENT 1 # Forced residency flag (Yes = 1, No = 0)
}
} MULTIPROCESSOR 0 # 0 for single-processor, 1 for
} multi-processor
} NUMCPUVPS 1 # Number of user (cpu) vps
} SINGLE_CPU_VP 1 # If non-zero, limit number of cpu vps to one
}
} NOAGE 0 # Process aging
} AFF_SPROC 0 # Affinity start processor
} AFF_NPROCS 0 # Affinity number of processors
}
} # Shared Memory Parameters
}
} LOCKS 150000 # Maximum number of locks
} BUFFERS 200000 # Maximum number of shared buffers
} NUMAIOVPS 4 # Number of IO vps
} PHYSBUFF 32 # Physical log buffer size (Kbytes)
} LOGBUFF 32 # Logical log buffer size (Kbytes)
} LOGSMAX 60 # Maximum number of logical log files
} CLEANERS 48 # Number of buffer cleaner processes
} SHMBASE 0x0 # Shared memory base address
} SHMVIRTSIZE 40000 # 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 96 # Number of LRU queues
} LRU_MAX_DIRTY 1 # LRU percent dirty begin cleaning limit
} LRU_MIN_DIRTY 0 # LRU percent dirty end cleaning limit
} LTXHWM 50 # Long transaction high water mark percentage
} LTXEHWM 60 # Long transaction high water mark (exclusive)
} NETTYPE ipcshm,1,100,CPU
} NETTYPE soctcp,1,30,NET
} TXTIMEOUT 0x12c # Tra