What is Livecache for ?

[Former Member]

Dear Gurus,

I'm new to SCM and I'm always facing problems regarding Liveecache, I'm functional consultant not a technical one but I need to break through this issue.

I read posts about the LC and I got some saying that master data are on the APO DB and the transaction data are on the LC DB, but I can't find this information on SAP's site.

So please guide me about what is LC for, what kind of data are stored on it, what are the steps after installing this component, as I'm stuck now on an error telling me that I'm having invalid planning version Message no. /SAPAPO/OM015

, and please keep the answer as simple as possible.

Thanks in advance.

MaX

[Former Member · Accepted solution]

MaX

At a high level, Livecache is SAP's 'memory resident' database for APO. Planning engines (such as CTM, PPDS, Optimizer, heuristics) need to crunch through large volumes of data (i.e, a large number of product locations) in short periods of time. At the same time time not all of the data elements of a planning object are relevant during planning. So the approach taken is to keep critical (and minimal) data in Livecache and keep the rest in the database (on disk). The data in LC and the data in the database is linked through the use of GUID's.

I would suggest you read some basic books on APO by Dickersbasch, Daniel Wood etc in addition to the SAP links mentioned by DB49. They do a decent job of explaining architechture and data structures.

For the problem you mentioned, try running Livecache Consistency Check (/SAPAPO/OM17) with none of the options ticked and with the planning version you are having difficulty with. It often occurs that Planning Versions exist only in Livecache or only in Database. This consistency check will be able to correct it.

Rishi Menon

[Former Member]

The same question had haunted me once. I would explain in a very simple language.

SAP liveCache is the database management system for SAP APO. It is used to process large volume of data real-time, like planning data in SAP APO. In SAP SCM, planning runs at times for 12 hours! So high performance is needed from the database systems which is not possible by conventional DBMS like SQL. So SAP came up with SAP liveCache.

Here, data is processed in main memory, so the disk does not have to be accessed as often. LiveCache database system switches between two database models: high level queries such as sales or purchase orders are executed in SQL, while lower level data intensive queries of individual items, such as raw materials and BOMs, are executed in the object-oriented database system.

Also a note: Here the data remains in summarized form rather than normalized form in which data resides in conventional DBMS. Also remember that L/C is a major selling point for APO!

I hope this helps.

[Former Member]

Thanks Rah for your explanation, one more thing if you can help me with, when i restart the server i found that the livecache shutdown....should I shut it down before restarting like what I do with SAP Service? And after starting it, should I initialize every time, and what is initialaiztion for in simple words also.

Thanks in advance

Regards,

MaX

[Former Member]

Max,

I read posts about the LC and I got some saying that master data are on the APO DB and the transaction data are on the LC DB, but I can't find this information on SAP's site.

That is probably because it is only partly true. Some bits of master data exist in LC, and some bits of transactional data exist in disc storage (not Livecache).

For a high level overview of Livecache, consult SAP online documents.

http://help.sap.com/saphelp_scm70/helpdata/EN/f2/0271f49770f0498d32844fc0283645/frameset.htm

More technical:

http://service.sap.com/~form/sapnet?_FRAME=CONTAINER&_OBJECT=011000358700000785742007E

Maintenance:

http://service.sap.com/~sapidb/011000358700002213412003E

http://service.sap.com/~sapidb/011000358700007382632002E

http://service.sap.com/~sapidb/011000358700008748092002E

My experience is that there are very few errors that are correctable by a functional consultant, except during development of a new solution. Logical or setup errors can trigger LiveCache errors. One a solution has stabilized, the remaining LC errors are typically correctable only by a basis admin.

Your error could come from just about anything, if you are developing a new solution. Try OSS. Here are a few notes I found that may be relevant

https://service.sap.com/sap/support/notes/792803

https://service.sap.com/sap/support/notes/519014

https://service.sap.com/sap/support/notes/571031

There are more.....

Best Regards,

DB49