Last year, Apple finally worked enough with Microsoft to get the iTunes program for windows available in the Microsoft Online Store. I’d always had problems with upgrading iTunes in windows in the past, requiring me to completely uninstall, reboot, and install the new version each time I wanted to upgrade. Often I had to not just uninstall iTunes, but search for other helper programs that Apple might have installed and uninstall them before rebooting. I did the complete uninstall before I installed the version from the Microsoft store. Since that time, iTunes has almost magically been up to date on my desktop computer. The Microsoft store updates seem to get installed in downtime on my computer and everything just works.
I’m stuck in my ways a bit as far as music goes. I’ve get a large ripped CD collection, that I keep the originals all in a set of binders including the original paper inserts. My iPhone has 256GB of storage, more than half of which is my music.
I’ve kept my iPhone synchronized with my desktop computer because of the storage requirements of all of the music in the past, but at times have wished I was synchronizing with my Microsoft Surface Pro 4 tablet that I travel with, and use just as much as my desktop. My Surface has 256GB of storage in the internal SSD, and I’ve been using a 256GB micro sd card in the accessible storage slot for the past couple of years. That’s good for movies while traveling, but I didn’t want to allocate over half the space to iTunes.

The falling price of flash cards recently convinced me to buy a new 512GB flash card to leave in the Surface. I was able to get all of my music transferred over to the SD card and iTunes installed from the Microsoft Store with very little impact on the internal storage on my Surface. I followed the Apple support ducument and had a few issues because my library had never been consolidated from my early MP3 ripping days.
I’ve been running my Surface SSD with between 50 and 70GB free, which from what I’ve read about SSD usage is good for both lifespan and performance. The iTunes directory on my micro SD card consists of 24,169 files and 137,859,861,360 bytes according to a simple dir /s command.
All was looking good until I got around to connecting my iPhone to the new machine and telling it to backup on the new machine. The backup completed correctly, but I then found out that it had used up all the free space on my internal SSD and I was now down to less than 3GB free space.
A quick search on the web led me to this page explaining how to relocate the backups to an external drive in windows. That seemed good, until I realized that the directory described does not exist on my machine. One more change that seems to have happened to iTunes locations in the Microsoft Store move. A search on my machine led me to find the MobileSync directory in my user profile directory. I used robocopy to move the backup directory to an appropriate directory on my flash card, which took a while because it consisted of 58,623 files and 77,743,703,474 bytes. I then created a directory junction from the SSD location to the flash location.
robocopy /COPYALL /E /MOVE C:\Users\Wim\Apple\MobileSync\Backup D:\Wim\Apple\MobileSync\Backup
mklink /J C:\Users\Wim\Apple\MobileSync\Backup D:\Wim\Apple\MobileSync\Backup
After all that had completed I started iTunes and connected my phone, initiating another backup. Everything now appears to be working properly, with iTunes storing both it’s library and device backups on my secondary storage device.
The only drawback I’ve currently run into is that I use Windows Server Essentials 2016 as a home server and it’s device backup feature to backup my machine for emergency file recovery. The microsd card is recognized as removable media, and the backup software doesn’t easily let me include it in the regular backup strategy.