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unlimit for Oracle

Arun Vijay V C
Frequent Advisor

unlimit for Oracle

Hello All,

we are asked to set unlimit for oracle user for all the values.
teh current value is

$ ulimit -a
time(seconds) unlimited
file(blocks) unlimited
data(kbytes) 1048576
stack(kbytes) 131072
memory(kbytes) unlimited
coredump(blocks) 4194303
nofiles(descriptors) 2048

Server has 32GB Phy mem and its mem utilization is always high (98-99%).

Can you tell me whats the challenges included in setting unlimited for all the parametor for Oracle?

Before setting it what we need to check?

Dennis Handly
Acclaimed Contributor

Re: unlimit for Oracle

>we are asked to set unlimited for oracle user for all the values.

You can't. You can only set the corresponding kernel parms larger.
What HP-UX version are you using?
Occasional Advisor

Re: unlimit for Oracle


ulimit -n 4096
ulimit -c unlimited

These will only work if ulimit -aH (Hard Limit Values) allows it

For more info on impact, please see:

If you found these answers helpful, please read:

1. ulimit -a
Display all configured values.
2. ulimit -c
Sets core file size
3. ulimit -d
Sets data seg size
4. ulimit -n
Sets Open Files
5. ulimit -s
Sets stack size
6. ulimit -u
Sets max user processes
7. ulimit -t
Sets cpu time
8. ulimit -v
Sets virtual memory
9. ulimit -p
Sets pipe size

Remon Samir
Honored Contributor

Re: unlimit for Oracle

On HP-UX, the hard limits for some ulimit parameters depend on kernel parameters. The kernel configuration does not accept "unlimited" for these parameters, only numeric values.

ulimit -H -d <= maxdsiz / maxdsiz_64bit

ulimit -H -s <= maxssiz / maxssiz_64bit

ulimit -H -n <= maxfiles_lim

But if you really want, you can set these parameters to very large values.

For example, you can set the hard limit for data (ulimit -d) to a value that is larger than the amount of RAM + swap you have in the system. If you do this and the Oracle ever attempts to use all the memory it can, the system will hang and essential system daemons will probably crash because of critical memory shortage.

Likewise, you can set maxfiles_lim to a value that is higher than your nfile kernel parameter: but when the total number of sockets and filehandles in use system-wide reaches the value of "nfile", no more sockets or filehandles can be allocated. At that point, any program that requests to open a file will not succeed. Again, this may cause essential system daemons to crash.