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Re: nfile utilization and requirement

 
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Suni Raj
Advisor

nfile utilization and requirement

Hi,

One of my HP-UX servers running v11.00 on a N4000 hardware has a consistent 79%utilization of nfile. Now the application requires to upgrade the nfile parameters. Present value is 250000. Other suporting kernel parameters are:

maxusers=2048
nproc = 20500
npty= 256

This server has a good amount of 14 Gig memory. The o/p of glance (process details)is attached.

Now, can I get some information about the following:

1.Upto how many Gig, I can upgrade my physical memory?

2.If I upgrade my memory, upto what extend can I upgrade my nfile value without affecting the memory utlization? I mean to ask the proportionate value of nfile?

Thanks!
Raj
7 REPLIES 7
Sundar_7
Honored Contributor
Solution

Re: nfile utilization and requirement

As far as I know, nfile value doesn't depend on the physical memory you have in the system. It merely defines the max number of files that can be open at any given point of time, system wide.

But ofcourse, increasing nfile to an extrmely high value would mean the kernel image will be bigger to accomodate the structures.

Learn What to do ,How to do and more importantly When to do ?
James R. Ferguson
Acclaimed Contributor

Re: nfile utilization and requirement

Hi Raj:

First, disregard any formula used to calculate the 'nfile' setting. Simply choose a value for 'nfile' that meets your needs.

The value of 'nfile' represents the number of slots in a kernel table used to track open files. The memory required per slot is minimal, so increasing 'nfile' has very little affect on overall memory consumption.

Regards!

...JRF...
Court Campbell
Honored Contributor

Re: nfile utilization and requirement

Max memory for an N4000 is 36Gb. But upping nfile should not use that much memory. Upping nfile just means that you can have only that number of files open simultaneously. you should be able to increase this parameter without adding more memory.
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Suni Raj
Advisor

Re: nfile utilization and requirement

Sundar/JRF/Court, thanks for your prompt response. I am going to hp to give their recommendation in this regard. Thanks again!

Raj
Bill Hassell
Honored Contributor

Re: nfile utilization and requirement

You can raise nfile to several hundred thousand, even one million or more. Every table entry for nfile requires memory but it is far too small to worry about. Do not raise nfile to 250,000 if you are only using 50,000 as this is just a waste of space. As mentioned, nfile is not related to memory size. Note that every network connection requires a file handle and that you must change not only npty but nstrpty and nstrtel as well. Make them all the same.


Bill Hassell, sysadmin
Suni Raj
Advisor

Re: nfile utilization and requirement

Bill,

MY current nfile value is 250,000 and it is being utilized around 79% of this value! That is the reason behind this requirement. I got a recommendation from the vendor that I can go upto 350,000 with the current memory size(14 gig), but there could be a 5-10% more memory utilization. So I am going to try this value and test.

Thanks for your valuable time.

Raj
Bill Hassell
Honored Contributor

Re: nfile utilization and requirement

> MY current nfile value is 250,000 and it is being utilized around 79% of this value! That is the reason behind this requirement. I got a recommendation from the vendor that I can go upto 350,000 with the current memory size(14 gig), but there could be a 5-10% more memory utilization. So I am going to try this value and test.

The vendor's quote must be referring to the increase in the number of additional processes because 5-10% of 14Gb is 700 to 1400 megs and 100,000 increase in nfile won't be be more than a few dozen megs of kernel memory. You can certainly bump the value up to 350k or even 500k and then reboot to see how much space the kernel is now using.


Bill Hassell, sysadmin