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Ulimit values

Let  me know what is the ulimit command use and what is the default value
I can see the output from my ESXi host,

~ # ulimit
unlimited
~ # ulimit --h
-ash: ulimit: illegal option --
~ # ulimit -a
time(seconds)        unlimited
file(blocks)         unlimited
data(kb)             unlimited
stack(kb)            512
coredump(blocks)     0
memory(kb)           unlimited
locked memory(kb)    unlimited
process              64
nofiles              256
vmemory(kb)          unlimited
locks                unlimited
~ # ulimit
0
kbjijo
Asked:
kbjijo
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1 Solution
 
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
It displays the memory stack

The stack is nothing but a memory storage which is used by programs to hold intermediate results and subroutine return information. The default size of stack is 10240 KB. You may check it by executing "ulimit -a" command.

The stack reclaim the memory when a process exits. If you allocate more memory in stack, but the memory is not available then it may crash due to stack overflow.

If the stack size is set to too small value and this is not enough for a program then it will fail.

Defaults are as follows:- for ESXi 4.1

time(seconds)        unlimited
file(blocks)         unlimited
data(kb)             unlimited
stack(kb)            512
coredump(blocks)     0
memory(kb)           unlimited
locked memory(kb)    unlimited
process              64
nofiles              256
vmemory(kb)          unlimited
locks                unlimited

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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
see also here for syntax

http://ss64.com/bash/ulimit.html
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Gerwin Jansen, EE MVETopic Advisor Commented:
Hi, the ulimit man page is here
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kbjijoAuthor Commented:
Thanks a lot for the details............

What is nthe default nofiles  value for ESXi 4.1 ( ulimit -n ). If it is 256, can we able to change the value
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
default values are listed , for nofiles 256.

You should only change the values if advised by VMware Support or Vendor.

Why do you need to change the default values?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
also note, that ESXi is not Linux.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
yes, you can change the values if you want, to increase maximum number of open file descriptors

ulimit -n 512 will change the limit to 512
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kbjijoAuthor Commented:
Couple of queries

1 Is any impact after changing the values
2 This uLimit parameter is specific to the stripped down ESX OS running on the Blade.  Could there really be a link between the ESX uLimit and the guest virtual server OS setting ?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
1. it's not supported, unless VMware Support or Vendor support has indicated a value needs changing.
(any unsupported hack on the HYpervisor OS, could impact the Hypervisor OS, and stability of the OS, hence why there is a warning when using Console Mode of the Hypervior OS)

You have activated Tech Support Mode.
The time and date of this activation have been sent to the system logs.

VMware offers supported, powerful system administration tools.  Please
see www.vmware.com/go/sysadmintools for details.

Tech Support Mode may be disabled by an administrative user.
Please consult the ESXi Configuration Guide for additional
important information.


2. it is specific to the Hypervisor OS.

Tweak the values at your own risk!
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