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NFile setting for Oracle

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Lai Nee Shyang
Occasional Visitor

NFile setting for Oracle

Hi there,

I've a SAP system running oracle on HP-UX 11.0. The host (database server) is a V-class machine with 16Gbyte Memory, 14 CPUs, 3TByte storage. The current Nfile useage at peak is about 234201 out of 300010 (78%) and still increasing. Is there a limit of Nfile setting, for HP-UX kernel or/and Oracle.? Should I further increase the 300010 nfile limit?


Nee Shyang
Dan Hetzel
Honored Contributor

Re: NFile setting for Oracle


Shouls I say : "the sky is the limit" ?
In fact, nfile is only limited by your system memory, so you may still increase its value.

Here is a link with good explanations about configurable kernel parameters:

Best regards,

Everybody knows at least one thing worth sharing --
Alex Glennie
Honored Contributor

Re: NFile setting for Oracle

NB : I'm not an Oracle dba but found the following info & eg that may help ?

A SAP work process connects to an oracle shadow process to do it's work for it.

The shadow process opens database files,
however, as you increase sap workprocesses, you get more shadow processes, each shadow process can potentially open all the database files.
& there seems like there is a maxof 300 on the shadow processes, so worst case scenario is that nfile should be

# of shadow x #of files that make up the database
+ some overhead for the system.

eg db using file systems for the database, it has 123
seperate files x 300 shadow processes = 36900 , plus some for the system,s o nfile should stabilize around 40000 worst case.

seems that sap and oracle is very inefficient in this respect. if you use raw file systems you would not see this as you would only open fd to the rlvol and oracle would take it from there.

The research i've found indicates that you just up nfile until sap and oracle is happy.
Lai Nee Shyang
Occasional Visitor

Re: NFile setting for Oracle

Hi Dan and Alex,

Thanks. That's what I need, both on OS aspect and SAP/Oracle aspect.

Thanks guys.

Carlos Fernandez Riera
Honored Contributor

Re: NFile setting for Oracle

Alex is almost OK. I dont know other limit for shadows process than memory and tunable paramters, both unix and oracle.

About ussing raw devices, the number of fd is the same as is using filesystem, because shadows open datafiles for read.

You must review nfile, numproc, maxfiles and other in UX side, and similar parameters for oracle ( nfiles, processes ...).

The best is your are previewing problems.

Good job.