How to move an Apple Photos for OS X library to an external drive<article>
<section class="page">
<p>
Rick Henningsen has a Photos Library question:</p>
<p>
I want to move my Photos Library from the boot drive to a larger external drive. I suspect that I should <strong>not</strong> just move it in the Finder and then designate the library on the new drive as the system library.</p>
<p>
Remarkably, you
can just move it!</p><ol>
<li>Quit Photos.</li>
<li>Copy the Photos Library by dragging it from the startup volume to your external volume.</li>
<li>When complete, hold down the Option key and launch Photos.</li>
<li>In Photos, select
Photos > Preferences, and in the General tab, click Use as System Photo Library.</li>
</ol>
<figure class="large ">

<figcaption>
<p>
iCloud lets you open other Photos libraries.</p><p class="jumpTag"><a href="/article/2999846/photography/how-to-move-an-apple-photos-for-os-x-library-to-an-external-drive.html#jump">To read this article in full or to leave a comment, please click here[/url]</p></section></article>
Source:
How to move an Apple Photos for OS X library to an external drive