iOS 9 onwards; iTunes U materials; Apple
Books; and some mobile components
such as high–quality voices for Siri and
language dictionaries.
DOES CACHING WORK EVERYWHERE?
There are some restrictions. The registered
owner of the content cache on macOS
must match the region of the client Apple
ID accounts, so for example if your iOS
devices have US Apple IDs then your Mac
must too. Some content isn’t cached in
some countries, for example iTunes
downloads aren’t cached in Brazil, Mexico,
mainland China or Portugal, and Apple
Books downloads aren’t cached in Canada.
WHAT DEVICES CAN USE CACHING?
You can use Apple’s content caching on
Macs, iOS and iPadOS devices, and Apple
TV. Those devices need to be on networks
that use Network Address Translation
(NAT) or that have publicly routable IP
addresses. You can also use what’s called
“tethered caching” to share the cache
with iOS devices over USB.
In terms of operating systems, content
caching works without conĽguration on
devices running iOS 7 or later, or Mac OS
X 10.8.2 Mountain Lion or later. The host
needs macOS 10.13 High Sierra or later.
HOW DO I GO ABOUT SETTING UP
CONTENT CACHING ON MY MAC?
On the Mac you want to use to host the
data — one that’s got lots of storage
space, because it’s going to be storing a
lot of stuļ — go into System Preferences
Sharing > Content Caching. You’ll see
a list of the sharing services available on
your Mac — DVD sharing, screen sharing,
Ľle and printer sharing, and so on.
At the bottom of that list you’ll see
a check box for content caching. Check
it and you’ll see the message “Content
Caching is starting” next to a yellow
indicator. It’ll turn green after a few
seconds. You can then use the Cache
menu to select what content you want
to cache: all content, only shared content,
or only iCloud content. If you click
on Options you can specify where the
cache should be located and how much
storage you want to allocate to it.
Once you’ve done that, restart the
devices that you want to use the cache
with and they should discover and use
it automatically. If your network uses
multiple IP addresses, there are further
conĽguration settings, which Apple has
detailed at bit.ly/mac354chngdy.HOW DO I GET THE BEST PERFORMANCE
FROM CONTENT CACHING?
Content caching can work over Wi–Fi but
it isn’t recommended unless you have no
alternative. For best results, Apple says
you should set up content caching on
a Mac that has a single wired gigabit
Ethernet connection to the network. The
more devices on your network, the more
important that becomes: if you’ve got
multiple devices looking for updates, that
can mean a lot of network traL·c and any
bottleneck is likely to be due to your
cache’s network connection.
Apple recommends using Activity
Monitor to keep an eye on your caching.
If you look at View > All Processes > CPU
> AssetCache and that process’s CPU load
is running very high, that’s a sign that
your cache is under a lot of strain. You
may want to consider adding one or more
additional caches to spread the load
rather than hammer a single Mac.
It’s crucial that your cache has got
suL·cient storage for the data you want to
share. If it doesn’t, your Mac will delete
old cached data to make room for new
downloads — and that could mean it
having to re-download the same things
again and again, which defeats the whole
point of setting up content caching in the
Ľrst place! CARRIE MARSHALLGENIUS TIPContent caching is a great
way to put an old Mac
mini back into circulation
as a host device. Mac
minis have had gigabit
Ethernet since 2006.JARGON BUSTERNetwork Address
Translation (NAT) enables
multiple devices in a local
network to use the same
IP address to connect to
the internet.Image rights: Apple, Adobe.
When you enable content
caching in System Prefs
> Sharing, you can choose
whether to cache
everything or limit it to
iCloud or shared content.How to do anything on your Mac, iPhone & iPad
maclife.com SEP 2020 85