log_io_queue size

[Former Member]

Hi,

We have a high number of log i/o queue overflows in the system (maxdb 7.5) .

I know that I need to increase the log_io-queue parameter to fix , but got a bit confused with the explanationfor the limits.

The lower and upper limits are:

LOG_IO_QUEUE < LOG_VOLUME_SIZE_*

AND

LOG_IO_QUEUE >= 2 * MULTIO_BLOCK_CNT

(2 bytes integer)

the lower limit needs to higher than 16 (2* multi_io_block_cnt which is 😎

but with the upper limit does log_volume_size_* means the size of the log file, which is 4Gb.?

I presume that the size is set in pages which would mean that the max size should be lower than 512000 ( 4Gb / 8kb) ?????

[Former Member · Accepted solution]

Hello,

my experience in the maxDb development Support is that the custoemr don't use such huge size of LOG-IO-Quues (Maximum = LOG-Volume SIZE). The recommended value for LOG_IO_QUEUE is between 1000 and 2000 in SAP environment.

If you have a high number of LOG-Queue-Overfloes you should check the Size of the LOG_IO_QUEUE Parameter but you should check the I/O responsetime of the LOG-Volume (DISK) as well. If you have bad IO time when you write this affects LOG-QUEUE-Overflows as well.

Regards, Christiane Hienger

MaxDB Development Support

SAP AG

[Former Member · Accepted solution]

hello christiane,

thanks for your information - log_io_queue value.

I got the same problem. I have already increased the parameter LOG_IO_QUEUE from 66 to 100 manually. I thought this would be automatically handled. Now, I see the current parameter value is beetween 1000 and 2000. Today - I have the same problem, an I would to increase from 100 to 1000. I will see.

I wonder, however, that the logs are written so irregularly.last week nothing, then 5 logs today. Is there a bottleneck?

background-infos:

DB Version Kernel 7.6.03 Build 008-123-159-187

DBM-Server-Version DBMServer 7.6.03 Build 008-123-159-187

OS Windows Server 2003 family

####

SAP R/3 Kernel 640_REL

Datenbank Client Library SAPDB 7.4.3.049 ??? thats too old, not really

hergestellt auf NT 5.0 2195 Service Pack 4 x86 MS VC++ 13.10

hergestellt am Aug 17 2007 00:20:23

Support-Level 0

Kernel Patchnummer 196

Source-Id 0.196

DBSL Patchnummer 120

ICU Version 2.6.1 Unicode Version 4.0

R/3 4.7 x 110 (HR)

####

Auto-Log ON

Redo-LOG ON

regards,

christoph