Nametab (NTAB)

[former_member182034]

hi All,

I am getting issue in NTAB buffer mean there are directory and size is showing Zero.

Buffer             HitRatio % Alloc. KB Freesp. KB % Free Sp. Dir. Size FreeDirEnt % Free Dir    Swaps  DB Accs

Nametab (NTAB)                                                                                0
  Table definition     97.79    21,809                          64,167                         25,828   93,281
  Field definition     96.66   101,318      2,470       2.56    64,167     47,493      74.01   51,651   98,126
  Short NTAB           99.27    11,636      8,582      89.11    16,041     12,919      80.54        0    3,122
  Initial records      77.64    21,266     13,430      69.73    16,041      3,562      22.21        0   12,481

here some column(Freesp. KB, % Free Sp., FreeDirEnt ,% Free Dir) are showing blank mean there is not free directory.

Table Definition

 Efficiency        HITRATIO          %        98
                   HITS                4,135,230
                   REQUESTS            4,228,527
                   DB access quality %        98
                   DB access              93,281
                   DB access saved     4,135,227
                   Reorgs                      0
 Size              Allocated        KB    21,809
                   Available        KB    18,297
                   Used             KB    18,297
                   Free             KB         0
                   Free             KB         0
 Directory entries Available              64,167
                   Used                   64,167
                   Free                        0
 Swaps             Objects swapped        25,828
                   Frames swapped              0
 Resets            Total                       0

while current value of Nametab is:

rsdb/ntab/entrycount 64167

rsdb/ntab/ftabsize 96305 kB

rsdb/ntab/sntabsize 9631 kB

rsdb/ntab/irbdsize 19261 kB

anyone tell me how can i calculate the value of above parameter?

or

should i have to increase the value of rsdb/ntab/entrycount if yes than how much mean %?

Regards,

[xymanuel]

Hi Majamil,

there are 2 Buffers swapping

Table definition and Field definition

The parameter which is responsible for the Table definition is rsdb/ntab/entrycout.

Increase it to 100.000 which is ~ 34 MB Memory.

The Field definition Buffer is controlled by two parameters

rsdb/ntab/ftabsize and

rsdb/ntab/entrycount (it is the same as for the Table definition!)

Your Field definition Buffer allocates 101,318 KB and has 47,493 % free Directory entries. This means,

that you only need to push up the rsdb/ntab/ftabsize and not the maximum possible entry count of objects stored.

As a rule of thumb you can increase these parameters by 20% steps if they are swapping.

-> You have rsdb/ntab/entrycount 64167 (what a weired value ). 20% bigger is 78000.

-> Or rsdb/ntab/ftabsize 96305 kB + 20% is ~120.000

Be sure your Applicationserver has enough RAM to do this (today there should not be a problem).

Real world values for ECC 6.0 EHP 5 on Win 2008R2 i'm using are:

rsdb/ntab/ftabsize 200000 kB

rsdb/ntab/entrycount 200000

Kind regards

Manuel

[former_member182034]

hi manuel,

thanks for your detail reply,

dear,

Buffer             HitRatio % Alloc. KB Freesp. KB % Free Sp. Dir. Size FreeDirEnt  % Free Dir   Swaps  DB Accs
Field definition     96.66   101,318      2,470       2.56    64,167     47,493    74.01    51,651   98,126

Your Field definition Buffer allocates 101,318 KB and has 47,493 % free Directory entries

above 74.01 % free directories while you mentioned 47.493.

System Info:

PRD Database server:

ERP ECC6 with Oracle 10.2.0.5 on window 2008 while RAM 32 GB

would you please recalculate the value w.r.t above system info and send me.

Regards,

[xymanuel]

Hi majamil

hi manuel,
> thanks for your detail reply,
> dear, 
> 

> Buffer             HitRatio % Alloc. KB Freesp. KB % Free Sp. Dir. Size FreeDirEnt  % Free Dir   Swaps  DB Accs
> Field definition     96.66   101,318      2,470       2.56    64,167     47,493    74.01    51,651   98,126
> 
> Your Field definition Buffer allocates 101,318 KB and has 47,493 % free Directory entries
> above 74.01 % free directories while you mentioned 47.493.
47493 are entries not % ! 
> 
> System Info:
> PRD Database server: 
> ERP ECC6 with Oracle 10.2.0.5 on window 2008 while RAM 32 GB
> 
> would you please recalculate the value w.r.t above system info and send me.
> 
> Regards,

Your Field Buffer has a maximum of 64167 entries which is 100%

You have 47493 entries free, which is 74,01 %

ok?

I would recommend:

rsdb/ntab/ftabsize = 120000 (which is 120 MB)

rsdb/ntab/entrycount = 100000 (which are 100k entries)

After restarting the Appserver, you have to wait several days, to check if the buffers begin to swap again.

Kind regards

Manuel

[former_member182034]

Hi all,

the Directory and buffer size is showing zero after increase the value of above parameters,

Efficiency        HITRATIO          %         98
                  HITS                40,745,627
                  REQUESTS            41,557,695
                  DB access quality %         98
                  DB access              810,500
                  DB access saved     40,745,712
                  Reorgs                       0
Size              Allocated        KB     33,987
                  Available        KB     28,515
                  Used             KB     28,515
                  Free             KB          0
                  Free             KB          0
Directory entries Available              100,000
                  Used                   100,000
                  Free                         0
Swaps             Objects swapped        331,797
                  Frames swapped               0
Resets            Total                        0

would anyone tell that why the size of buffer and directory is doing to Zero?

how can I rectify this issue?

Regards,

Edited by: majamil on Mar 2, 2012 2:35 PM

[xymanuel]

Hi majamil,

as i can see, you increased the maximum possible entries from 64.000 to 100.000.

The size of your Buffer in memory increased from 22MB to 33,987MB which was quite a good start.

Now to your problem,

the goal is to reach a value where every table or tableentry which is marked as a "buffered

table", can be stored in the local memory of the application server.

e.g. Table T000 which stores the client info.

In SE11 under "technical settings" you see that this table is fully buffered.

This means that if an program does a "select * from T000" there will be an physical access

to the databases only the first time! A copy of the complete table will be stored in memory of the appserver which runs this statement.

The size of this memory is controlled by the table buffer parameter.

If again a program is run on this application server which does an "select * from T000", the

answer will come directly from the local memory, which is about 1000 times faster. (NO access to the database)

Think about the slow network between the applicationserver an the database.

In your case we see that the buffer is swapping. "Objects swapped 331,797"

This means, you have more tables set to "fully buffered" or "generic key buffered" than your buffer can handle.

To store the newer tableentry in memory the appserver dropps an already stored entry. This can be seen as a

buffer swap.

Now you have 2 possible ways to go.

1. Again increase your buffervalues.

e.g. this are values from our productive. Remember, the goal is that there are 0 objects swapping.

Efficiency        HITRATIO          %         100
                   HITS                151.225.411
                   REQUESTS            151.445.120
                   DB access quality %         100
                   DB access               219.709
                   DB access saved     151.225.411
                   Reorgs                        0
 Size              Allocated        KB      50.411
                   Available        KB      42.187
                   Used             KB      15.328
                   Free             KB      26.859
 Directory entries Available               150.000
                   Used                     54.514
                   Free                     95.486
 Swaps             Objects swapped               0
                   Frames swapped                0
 Resets            Total                         0

2.

Find tables which are excessive using the table buffer. Maybe a developer marked a table as "fully bufferd" which contains 100.000 rows and the data in the table changes very often. This will kill your buffer and result in high buffer swaps.

This can be done in ST07 -> SAP Buffer.

A way to analyse which Table uses buffer cache is ST10. Here you can validate if the buffering is senseless because of invalidations e.g. caused by changing data.

(If data in an bufferd table changes like our T000, the application server have to reload the table from the database. This also causes buffer swaps. Only buffer static data).

Kind regards

Manuel

[former_member182034]

Dear,

Thanks for your comprehensive reply.

would you tell me that how can we increase the buffer size of rsdb/ntab/entrycount because there is no showing any buffer parameter of ntab/entrycount.

Size           
Allocated        KB     33,987
                  Available        KB     {28,515}
                  Used             KB     28,515
                  Free             KB          0
                  Free             KB          0
Directory entries Available              100,000
                  Used                   100,000
                  Free                         0
Swaps             Objects swapped        331,797
                  Frames swapped               0
Resets            Total                        0

while these (FNAT,SNTAB, IRBD) have buffer parameters.

Regards,

[Former Member]

Hi majamil,

Check this if it helps you [http://help.sap.com/saphelp_nw04/helpdata/en/c4/3a6f4e505211d189550000e829fbbd/content.htm]

Regards,

Venkata S Pagolu

[former_member182034]

hi Venkata,

the current parameter value is:

rsdb/ntab/entrycount 100000

Unicode:

rsdb/ntab/entrycount´ 292 / 1024

would you explain me that how can i calculate the buffer value of rsdb/ntab/entrycount

Regards,

[Former Member]

Hi,

It depends on various things.

check this note which mentions clearly for setting the parameter rsdb/ntab/entrycount

SAP Note 16244 - Setting nametab buffer sizes

Regards,

Venkata S Pagolu

[former_member182034]

hi Dear,

Buffer          Kernel 6.20 and higher

TTAB           rsdb/ntab/entrycount

The total size (in KB) can be estimated as follows:

Kernel:               s_ttab  s_ftab  s_irbd  s_sntab

64-bit , Unicode     384         80       32         3

TTAB buffer = s_ttab * "rsdb/ntab/entrycount" / 1024

384*100000/1024=37500

is it Ok , please tell me the buffer parameter for this value 37500 or automatically assign this value to entrycount's buffer because there are exist the buffer parameters of IRBD,SNTAB,FTAB.

what do you say about ipc/shm_psize_40 mean if i increase the entrycount parameter value than it is compulsory to set this parameters or no need.

the ipc/shm_psize_40 is not showing in RZ11.

Regards,