Long checkpoints
Hi,
I would welcome suggestions on how to lower the checkpoint durations at
one of our sites. Relevant ONCONFIG parameters are given below. All
chunks are cooked files. At checkpoint time, there are on the average
about 500 dirty buffers to flush.
Thanks.
Alanoly Andrews.
======================================
Informix Dynamic Server 7.31 UC3 on AIX 4.3.2
-----------------------------------
Here are the last 20 lines of the Server Log:
10:31:34 Checkpoint Completed: duration was 10 seconds.
10:36:46 Checkpoint Completed: duration was 11 seconds.
10:41:55 Checkpoint Completed: duration was 10 seconds.
10:47:07 Checkpoint Completed: duration was 11 seconds.
10:52:15 Checkpoint Completed: duration was 9 seconds.
10:57:25 Checkpoint Completed: duration was 9 seconds.
11:02:35 Checkpoint Completed: duration was 9 seconds.
11:05:16 Logical Log 161 Complete.
11:05:16 Logical Log 161 - Backup Started
11:05:19 Logical Log 161 - Backup Completed
11:07:46 Checkpoint Completed: duration was 11 seconds.
11:12:55 Checkpoint Completed: duration was 9 seconds.
11:18:04 Checkpoint Completed: duration was 9 seconds.
11:23:13 Checkpoint Completed: duration was 8 seconds.
11:28:25 Checkpoint Completed: duration was 11 seconds.
11:33:33 Checkpoint Completed: duration was 9 seconds.
11:38:53 Checkpoint Completed: duration was 19 seconds.
11:44:03 Checkpoint Completed: duration was 9 seconds.
11:49:10 Checkpoint Completed: duration was 8 seconds.
11:54:21 Checkpoint Completed: duration was 10 seconds.
--------------------------------------
Relevant parts of the "onconfig" file:
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 vpsto one
NOAGE 1 # 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 45000 # Maximum number of shared buffers
NUMAIOVPS 2 # Number of IO vps
PHYSBUFF 64 # Physical log buffer size (Kbytes)
LOGBUFF 64 # Logical log buffer size (Kbytes)LOGSMAX 100 # Maximum number of logical log files
CLEANERS 2 # Number of buffer cleaner processes
SHMBASE 0x30000000 # Shared memory base address
SHMVIRTSIZE 100000 # initial virtual shared memory segmentsize
SHMADD 64000 # Size of new shared memory segments
(Kbytes)
SHMTOTAL 720000 # Total shared memory (Kbytes).
0=>unlimited
CKPTINTVL 300 # Check point interval (in sec)
LRUS 6 # Number of LRU queues
LRU_MAX_DIRTY 10 # LRU percent dirty begin cleaning limit
LRU_MIN_DIRTY 5 # LRU percent dirty end cleaning limit
LTXHWM 50 # Long transaction high water markpercentage
LTXEHWM 60 # Long transaction high water mark
(exclusive)
TXTIMEOUT 0x12c # Transaction timeout (in sec)
STACKSIZE 64 # Stack size (Kbytes)
======================================================
Sent via Deja.com http://www.deja.com/
Before you buy.
Try the following:
LRU_MAX_DIRTY 1
LRU_MIN_DIRTY 0
This will reduce the number of buffers that need to be flushed at checkpoint
time.
Also, you might try increasing the number of LRUS and CLEANERS so that they
are equal and so that you have about 1,000 buffers per LRU queue.
If you are not using KAIO, you need to increase the number of AIO VP's.
<alanolya@planmatics.com> wrote in message
news:8fheqd$baf$1@nnrp1.deja.com...
> Hi,
>
> I would welcome suggestions on how to lower the checkpoint durations at
> one of our sites. Relevant ONCONFIG parameters are given below. All
> chunks are cooked files. At checkpoint time, there are on the average
> about 500 dirty buffers to flush.
>
> Thanks.
>
> Alanoly Andrews.
>
> ======================================
> Informix Dynamic Server 7.31 UC3 on AIX 4.3.2
>
> -----------------------------------
> Here are the last 20 lines of the Server Log:
>
> 10:31:34 Checkpoint Completed: duration was 10 seconds.
> 10:36:46 Checkpoint Completed: duration was 11 seconds.
> 10:41:55 Checkpoint Completed: duration was 10 seconds.
> 10:47:07 Checkpoint Completed: duration was 11 seconds.
> 10:52:15 Checkpoint Completed: duration was 9 seconds.
> 10:57:25 Checkpoint Completed: duration was 9 seconds.
> 11:02:35 Checkpoint Completed: duration was 9 seconds.
> 11:05:16 Logical Log 161 Complete.
> 11:05:16 Logical Log 161 - Backup Started
> 11:05:19 Logical Log 161 - Backup Completed
> 11:07:46 Checkpoint Completed: duration was 11 seconds.
> 11:12:55 Checkpoint Completed: duration was 9 seconds.
> 11:18:04 Checkpoint Completed: duration was 9 seconds.
> 11:23:13 Checkpoint Completed: duration was 8 seconds.
> 11:28:25 Checkpoint Completed: duration was 11 seconds.
> 11:33:33 Checkpoint Completed: duration was 9 seconds.
> 11:38:53 Checkpoint Completed: duration was 19 seconds.
> 11:44:03 Checkpoint Completed: duration was 9 seconds.
> 11:49:10 Checkpoint Completed: duration was 8 seconds.
> 11:54:21 Checkpoint Completed: duration was 10 seconds.>
> --------------------------------------
>
> Relevant parts of the "onconfig" file:
>
> 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 1 # 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 45000 # Maximum number of shared buffers
> NUMAIOVPS 2 # Number of IO vps
> PHYSBUFF 64 # Physical log buffer size (Kbytes)
> LOGBUFF 64 # Logical log buffer size (Kbytes)> LOGSMAX 100 # Maximum number of logical log files
> CLEANERS 2 # Number of buffer cleaner processes
> SHMBASE 0x30000000 # Shared memory base address
> SHMVIRTSIZE 100000 # initial virtual shared memory segment> size
> SHMADD 64000 # Size of new shared memory segments
> (Kbytes)
> SHMTOTAL 720000 # Total shared memory (Kbytes).
> 0=>unlimited
> CKPTINTVL 300 # Check point interval (in sec)
> LRUS 6 # Number of LRU queues
> LRU_MAX_DIRTY 10 # LRU percent dirty begin cleaning limit
> LRU_MIN_DIRTY 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 64 # Stack size (Kbytes)>
> ======================================================
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Two obvious suggestions:
a) more cleaners.
b) lower lru min/max dirty -- in OLTP, i've seen them as low as 1 & 2
respectively. Writes in checkpoint may be 'more efficient', but lru writes
(as opposed to chunk writes during checkpoint) don't impact the system as
much.
<alanolya@planmatics.com> wrote in message
news:8fheqd$baf$1@nnrp1.deja.com...
> Hi,
>
> I would welcome suggestions on how to lower the checkpoint durations at
> one of our sites. Relevant ONCONFIG parameters are given below. All
> chunks are cooked files. At checkpoint time, there are on the average
> about 500 dirty buffers to flush.
>
> Thanks.
>
> Alanoly Andrews.
>
> ======================================
> Informix Dynamic Server 7.31 UC3 on AIX 4.3.2
>
> -----------------------------------
> Here are the last 20 lines of the Server Log:
>
> 10:31:34 Checkpoint Completed: duration was 10 seconds.
> 10:36:46 Checkpoint Completed: duration was 11 seconds.
> 10:41:55 Checkpoint Completed: duration was 10 seconds.
> 10:47:07 Checkpoint Completed: duration was 11 seconds.
> 10:52:15 Checkpoint Completed: duration was 9 seconds.
> 10:57:25 Checkpoint Completed: duration was 9 seconds.
> 11:02:35 Checkpoint Completed: duration was 9 seconds.
> 11:05:16 Logical Log 161 Complete.
> 11:05:16 Logical Log 161 - Backup Started
> 11:05:19 Logical Log 161 - Backup Completed
> 11:07:46 Checkpoint Completed: duration was 11 seconds.
> 11:12:55 Checkpoint Completed: duration was 9 seconds.
> 11:18:04 Checkpoint Completed: duration was 9 seconds.
> 11:23:13 Checkpoint Completed: duration was 8 seconds.
> 11:28:25 Checkpoint Completed: duration was 11 seconds.
> 11:33:33 Checkpoint Completed: duration was 9 seconds.
> 11:38:53 Checkpoint Completed: duration was 19 seconds.
> 11:44:03 Checkpoint Completed: duration was 9 seconds.
> 11:49:10 Checkpoint Completed: duration was 8 seconds.
> 11:54:21 Checkpoint Completed: duration was 10 seconds.>
> --------------------------------------
>
> Relevant parts of the "onconfig" file:
>
> 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 1 # 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 45000 # Maximum number of shared buffers
> NUMAIOVPS 2 # Number of IO vps
> PHYSBUFF 64 # Physical log buffer size (Kbytes)
> LOGBUFF 64 # Logical log buffer size (Kbytes)> LOGSMAX 100 # Maximum number of logical log files
> CLEANERS 2 # Number of buffer cleaner processes
> SHMBASE 0x30000000 # Shared memory base address
> SHMVIRTSIZE 100000 # initial virtual shared memory segment> size
> SHMADD 64000 # Size of new shared memory segments
> (Kbytes)
> SHMTOTAL 720000 # Total shared memory (Kbytes).
> 0=>unlimited
> CKPTINTVL 300 # Check point interval (in sec)
> LRUS 6 # Number of LRU queues
> LRU_MAX_DIRTY 10 # LRU percent dirty begin cleaning limit
> LRU_MIN_DIRTY 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 64 # Stack size (Kbytes)>
> ======================================================
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.