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Why is the Log Area size much smaller than the log volume

I have been following up on an Early Watch report that has been generated for our production SCM 5.0 system running liveCache 7.6.02 Build 14. The alert says "The LOG volumes size in your system is too small. Recommendation: Configure LOG Volumes to at least 2 GB". There are two interesting things about this.

1) I have spent the last couple of days reading all the OSS Notes, and MaxDB documentation I could find, and this does not seem to be documented as a recommendation anywhere. Does this seem like a realistic recommendation without taking into account the level of change actifity?

2) There is a single log volume allocated with size 2,097,160 KB. In production LC10 and DBMGUI report this to be correct size under volume details, but only list the total log area size as 1,706,328 (81% of the volume size). We have a non-production environment with exactly the same size log volume, but it reports that the log area size is 2,032,008 KB (97% of the volume). What leads to these different amounts of wasted space, and is there any way of getting the database to start using it?

Thanks,

Mark

Former Member
Former Member replied

Hello Mark,

You can enlarge the log queue (Run dbm command 'param_getexplain LOG_IO_QUEUE'), but it doesn't improve the system performance, because it doesn't accelerate the log writing. The I/O processes stay slow. Please check if the data and log devspaces are located in this system on the same hard disks.

The most effective way for avoiding of log queue overflows is to better the I/O processes by log writing. It is better to locate the log volumes on the different hard disk as data devspaces and to improve I/O write at OS level for the Log devspaces. Check whether the log devspaces can be moved to a faster disk, to accelerate the physical log I/O.

-> Please check the SAP notes 748225 & 993848

->For SAP liveCache documentation in English < See the SAP note 767598 >:

http://help.sap.com/saphelp_nw04s/helpdata/en/f2/0271f49770f0498d32844fc0283645/frameset.htm

< -> Glossary -> Database Analyzer -> Database Analyzer documentation

-> messages ->Log queue overflows >

-> I recommend you to create the OSS ticket to the component 'SV-BO-SCM' or 'BC-DB-LVC', therefore we could logon & check your system first to give you further recommendations.

Thank you and best regards, Natalia Khlopina

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