I have a v7 site with a lot of media (~150 GB) these are mainly images.

A section of the site is a gallery, where the admin user process is:

1. Make a folder in the media section
2. Uploads all the images to this folder
3. Creates a child node of the gallery node and this has a picker to choose the media folder and also a featured main image

The gallery page shows the featured image and title but when clicked it is blank. If however I go into Developer > Examine Management > InternalIndexer > Index info & tools and click on the Rebuild index button to rebuild the index it shows again fine until either I deploy another code change or the site restarts for some reason?

I can also replicate this consistently by deleting the \ExamineIndexes\Internal\Index folder from disk.

To try and avoid this issue on deployment (as I purge the entire site root folder on deployment) this and the media folder is outside of the site root and has a virtual directory to link it back up to these persistent folders.

The view for the gallery page is :

<div class="gallery">
    <p>@mediaFolder.Name</p>
    @if (mediaFolder.Children.Any())
    {
        foreach (var mediaItem in mediaFolder.Children)
        {
            string mediaExtension = mediaItem.umbracoExtension;
            if (mediaExtension == "jpg" || mediaExtension == "png")
            {
                <a href="@mediaItem.Url" class="itemFixHeightWrapper" title="@mediaItem.Name">
                    <img src="@mediaItem.Url?width=747&height=499" class="img-responsive" alt="@mediaItem.Name" />
                </a>
                counter++;
            }
            else
            {
                <!-- Item is a @(@mediaExtension == "" ? "Folder" : mediaExtension) -->
            }
        }
    }
    else
    {
        <!-- NO CHILDREN IN MEDIA FOLDER -->
    }
</div>

It always returns <!-- NO CHILDREN IN MEDIA FOLDER --> if the Internal index is not rebuild.

Is there a way to either trigger this rebuild process on startup or stop this issue happening?

I am also not sure if this is similar to https://our.umbraco.com/forum/using-umbraco-and-getting-started/100280-moving-umbraco-project-require-rebuild-index-to-work