We are using R/3 640 kernel (ECC 5.0) on AIX 64 bit. I have seen that we can use the ztta/roll_extension more than 2GB, so i tried giving value as ztta/roll_extension = 4000000000 in the instance profile but when we check the instance profile before activating it is giving error as ztta/roll_extension value is more 2174000000, are you sure to use it .. If we continue activating it, will it be consider after restart or will still try to take 2174000000 ?
Mark Nyhan replied
Hi Aravind S,
Just to add to what Federico said, the note #425207 (SAP memory management, current parameter ranges) lists technical limits for this parameter and others, warnings such as these are only due to internal database table of the system ranges but larger values are usable to the kernel. Therefore you can ignore warnings about parameter values and unknown parameters in general from RZ10 as long as you are following documentation or notes guidelines.
The note #789477 (Lots of Extended Memory on AIX (64-Bit) as of Kernel 6.20) recommends ztta/roll_extension of 2GB even though it is possible to increase it to current 4GB value or even higher.
You can always confirm used values of parameters via report RSPARAM also once instance was restarted with new value set in the profile. Setting ztta/roll_extension to 4GB may lead to total extended memory of the instance being exhausted faster and if exhausted then you may want to consider decreasing again.
Hope this helps,