what's the diff. between the two kernel params

[Kurtkarl]

Hi.

I'm running hp-ux 11.x on my workstation and I need increase the current size of our maxdsiz with the same value as what we have before the upgrade which is
maxdsiz = 2063806464
After checking my 11.x kernel for maxdsiz value. I noticed there are two maxdsiz with the ff values
maxdsiz = 67108864
maxdsiz_64bit = 17179869184
can I easily changed those with same value as our old value before the upgrade? if yes which of these two should I changed?

Thanks in advance
Joey

[Youlette Etienne_2]

Joey,

I just changed both of those values at once for our k580 11.0 system to 2.0 gb yesterday. The maxdsiz value is for 32 bit programs and the maxdsiz_64 bit is for 64 bit programs. So far, this has resolved the memory issues that I was encountering, though I am still monitoring he system.

[Kurtkarl]

Youllete,

Thus this mean, if the users compiles his 32 bit program on this workstation which has hpux 11.x installed, is he using the maxdsiz_64bit and not the maxdsiz? if that's the case why do I still need to increase maxdsiz? and who uses maxdsiz?

thanks
joey

[Jeremiah Campbell]

I think what youlette was saying was this

maxdsiz is for 32 bit programs

maxdsiz_64 is for 64 bit programs

[James R. Ferguson]

Joey:

From documents #KBRC00001954 & #KBRC00003451:

"With a 64bit kernel 32bit application will still only use the non 64bit kernel
parameters. So in this case the 32bit application will use maxdsiz, maxtsiz
and maxssiz. These parameters will need to be configured to suite your 32bit
applications."

"The main causes for memory inavailability are either:

1. Lack of swap space. The physical memory on the machine is not what determines the total memory available to processes running on a machine. Swap space is the limiting factor. Check "swapinfo -t" (must be root for this), it will give output of available physical, swap and total memory at the time it is run.

2. "maxdsiz" too small for a processes needs. On a per process basis, the kernel parameters "maxdsiz" (for 32-bit applications) or "maxdsiz_64bit" (for
64-bit applications) limit the amount of space a process is allowed. The OS will prevent a program getting more mallocable memory once it has either hit this limit or run out of swap (above). The values of these may be determined and changed from SAM. "top" or Glance can show how much memory a process is using. The total memory reported by either of these will include more than just
the DATA area (malloc memory); Glance can report for individual areas within
its memory region view."


...JRF...

[Antoanetta Naghiu]

If you are using X, going in sam->kernel params->configurable param and highlight the specific parameter (maxdsiz). Press F1. You'll get a short description of it.
Take a look as well at http://docs.hp.com/hpux/content/KCparam.MaxDsiz.html and you'll notice that the previous posts are right.

[Youlette Etienne_2]

Option #2 from James' reasons for memory shortages was what I was experiencing. Both the maxdsiz and maxdsiz_64bit were set to 1.6 gb and apparently whenever an Oracle process tried to allocate more space than this, it aborted with an "ora-04030 out of process memory" error. No swapping was occuring and very little page outs (the most was 3). So far we have not encountered this error, but the DBA's are monitoring the PGA. However, I did notice that the swap space usage increased from a max of 72 % before the change, to a max of 97 % after the size increase. Looks like I will have to increase this pretty soon.

I am not sure which of the programs running on the system are 32 bit or 64 bit either, since this system is a less than 1 year upgrade from a 32-bit system. So, since I only had a small window to make the changes (30 minutes for a production box that takes about 20 minutes to reboot), I opted to change both at the same time, just in case either a 32bit or 64 bit program was the problem. It's such a pain to schedule down time.