HCS Blog

The Caching Service updates it's registration with Apple every 55 minutes, as registrations expire on Apple's side after 1 hour. This mechanism not only allows for a crashed Caching server to be removed from registry but also to track changes in the public IP.

Changing the Only cache content for local networks setting causes an immediately re-registration, removing the local network range from the registration payload when the setting is turned off.

On Stop
When the Caching Server stops it deregisters with lcdn-registration.apple.com allowing clients to download updates from Apple servers again.

The –perfmode option indicates whether or not the performance mode has been enabled, dedicating resources to binaries within the Server app:

serverinfo --perfmode

If the performance mode has not been enabled then the output will be as such:

Server performance mode is NOT enabled.
To enable performance mode, you can also use serverinfo. This is the only task that the command does that can make any changes to the system and as such is the only time you need to elevate privileges:

sudo serverinfo —setperfmode 1

Or set the boolean value back to 0 to disable.

sudo serverinfo —setperfmode 0

Command to Troubleshoot OS X Server

Location of executable: /Applications/Server.app/Contents/ServerRoot/usr/sbin

Prevent the Photos app in OS X from launching when plugging in an iOS device.

This sets an OS X flag so not activate ImageCapture,Photos or iPhoto when an iOS device is detected.

1. Launch Terminal from the /Applications/Utilities.

2. Enter the following command:

defaults -currentHost write com.apple.ImageCapture disableHotPlug -bool YES

There is a very simple way to create an OS X 10.11 El Capitan installer.
You need the full installer of OS X 10.11 El Capitan and a USB Drive (or something similar)
 
 
OS X 10.11 El Capitan has an executable file createinstallmedia to make a bootable usb.


Command to make an external OS X 10.11 El Capitan installer
This is assumes you have a an external partition named "YOURVOLUMENAMEHERE” (You should probably change your volume name)
Make changed where appropriate

sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/YOURVOLUMENAMEHERE/ --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app/ --nointeraction

2. Type in your password (Assuming you are an admin)
3. You will see the following:

Erasing Disk: 0%... 10%... 20%...100%...
Copying installer files to disk...
Copy complete.
Making disk bootable...
Copying boot files...
Copy complete.
Done.

System Integrity Protection (SIP)

Apple has implemented a new security feature in 10.11, System Integrity Protection, which prevents even super users from altering the contents of files in key System folders. The flags for restricting the folders is applied at the time of installation and cannot be overridden. SIP is designed to protect System files from malware and viruses. 

Disabling SIP requires booting into the recovery partition to run the Terminal command below.

# csrutil disable

which should confirm with status message:

Successfully disabled System Integrity Protection. Please restart the machine for the changes to take effect.

Reboot back into the El Capitan system partition.  

To re-enable SIP, boot back into the recovery partition and set state to enabled:

# csrutil enable