HCS Blog

macOS Sierra 10.12.0

sudo killall -HUP mDNSResponder

OSX 10.11.0

sudo killall -HUP mDNSResponder

OSX 10.10.4

sudo killall -HUP mDNSResponder

OSX 10.10.0 – 10.10.3

sudo discoveryutil mdnsflushcache

OSX 10.9  – 10.8 – 10.7

sudo killall -HUP mDNSResponder

OSX 10.5 – 10.6

sudo dscacheutil -flushcache


Windows:

ipconfig /flushdns


Linux (depending on what distribution you’re running)

/etc/init.d/named restart

/etc/init.d/nscd restart

This command will find all files on your hard drive that are larger than 1GB and print them to the screen with the file path.

Use this to find all locked files. This example searches the entire HD but you can navigate to a path if necessary.

find / -flags uchg

I viewed the system log files and saw the following error message every two minutes:

Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.d/other: Too many open files
Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.conf: Too many open files


I ran the “ulimit -a” command to see what the default open file size and Max user processes size were.  They were 256 and 709 which is very low.

ulimit -a 

core file size          (blocks, -c) 0  
data seg size           (kbytes, -d) unlimited  
file size               (blocks, -f) unlimited  
max locked memory       (kbytes, -l) unlimited  
max memory size         (kbytes, -m) unlimited  
open files                      (-n) 256  
pipe size            (512 bytes, -p) 1  
stack size              (kbytes, -s) 8192  
cpu time               (seconds, -t) unlimited  
max user processes              (-u) 709  
virtual memory          (kbytes, -v) unlimited  

I created two plist files that will change the default open file size and max user processes size limits to 524288 and 2048 and and put them in the following location:

/Library/LaunchDaemons/limit.maxfiles.plist

/Library/LaunchDaemons/limit.maxproc.plist

After a reboot, a re ran the ulimit -a command and the changes were now in effect.  I monitored the system log and these errors are now gone.

Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.d/other: Too many open files
Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.conf: Too many open files




ulimit -a  

core file size          (blocks, -c) 0  
data seg size           (kbytes, -d) unlimited  
file size               (blocks, -f) unlimited  
max locked memory       (kbytes, -l) unlimited  
max memory size         (kbytes, -m) unlimited  
open files                      (-n) 524288  
pipe size            (512 bytes, -p) 1  
stack size              (kbytes, -s) 8192  
cpu time               (seconds, -t) unlimited  
max user processes              (-u) 2048  
virtual memory          (kbytes, -v) unlimited

There is a feature on Cisco switches called “DHCP Snooping”.  This feature seems to break Netbooting from OS X servers.  The Netboot image will advertise on your network but you will not be able to boot from it.  To solve the problem you need to Trust DHCP Snooping on the Cisco port that the OS X Netboot server is plugged into.

On a Cisco switch, the commands should be similar to what’s shown below:

Myswitch(config)#interface GigabitEthernet3/47

Myswitch(config-if)#ip dhcp snooping trust

If you’re having this issue and your NOT using Cisco switches, check your switch manual to see if DHCP Snooping is supported and disable it on the switch port that your OS X server is plugged in to.

cp /Library/Desktop\ Pictures/Solid\ Colors/Solid\ Aqua\ Blue.png /Library/Caches/com.apple.desktop.admin.png