No swaps anyware still hit Ratio around 4% for Initial Record Buffer

Question

Dear Gurus
I am using ABAP NW7.0 System.
in the system all buffers  have hit ratio  99+%
but the initial record buffer hit ratio it below 10%
any way there is no swaps at all still hit Ratio is 4%
The current parameters are:
rsdb/ntab/irbdsize   --->6000
rsdb/ntab/entrycount---> 20000
HITRATIO  -
>        %         4
HITS         -
>              64
REQUESTS    -
>             1.729
DB access quality %   -
>       4
DB access      -
>          1.656
DB access saved    -
>         64
Reorgs        -
>               0
Allocated     -
>    KB     6.625
Available     -
>    KB     6.000
Used         -
>     KB     1.099*
Free         -
>     KB     4.901
Available     -
>           5.000
Used         -
>            1.656
Free           -
>         * 3.344*
Objects swapped    -
>          0
Frames swapped    -
>           0
Total          -
>              0
Pl suggest me how can i have the hitratio more.
Thanks in advance

Answer 1

Hello,
Unfortunately we can not tell exactly why the value is low,
however it is not necessarily an incorrect value.
The quality of a buffer and how often it is accessed is measured by the
'%Hit Ratio'. This value will indicate if the information stored in the
buffers, such as table entries, programs and screens, is being hit
directly from the buffer itself or, on the other hand, if the system
needs to bring that data from the database since it was not found in the
buffer.
To find out the buffers with poor quality, first check the system
startup time. When the system is started, all buffers (except the
program buffer which has a pre-load) are initially empty. Therefore,
all objects that are accessed for the first time have to be read from
the database and then loaded into the buffers.
If objects are not yet in the buffer, the hit ratio for the buffer will
be low. The hit ratio increases from the time objects are loaded into
the buffers. The rate of the increase depends on the workload in the
system and is different for each buffer.So it is to be noted that how often you restart the system which resuls in the loading of object again and causes hit rate to be low.
Poor buffer quality is not always due to a real problem. For example,
transports into a system can reduce buffer quality. Keep in mind though
that a value lower does not always shows that you have a problem.
A more pressing concern would be if we saw swaps on the system. As you
can see, there are no swaps.
Swapping occurs when the buffer is full, and the SAP System has to
load additional objects into the buffer. Objects in the buffer that
were used the least recently are removed. In this context, the term
"swap" means the objects removed from the buffer are lost and cannot
be replaced until a new database access is performed (replacing what
was lost).
There are two possible reasons for swapping
1 There is no space left in the buffer data area
  The buffer is too small. You should increase the buffer size.
2 There are no directory entries left.
Therefore, to conclude, although the hitratio appears low it does
not mean that there are any performance issues. The fact that there is
sufficient free space and there are no swaps confirm this.
You can try to increase size of intial record buffer(in steps) as from current setting it seems to be small.
I hope this helps.
Regards,
Archana