File format for RAID and NAS Drives and Backup Software to a NAS?

I am looking to purchase a Mac Mini and a storage solution for ~20TB of data including Time Machine, photos and movies (Plex server).

My plans were to purchase two Synology NAS servers, one for storing the original data and the second as a backup.

I understand that I can not format a networked NAS server with APFS or Mac OS Extended, will this be an issue (e.g. file names, speed etc)?

Would I be better off connecting a RAID (e.g. OWC) to the Mac Mini, which can be Mac OS Extended formatted (which I understand is advisable ahead of APFS) to store my data and backup to a NAS server?

What software will allow me to backup from a RAID drive connected to my Mac Mini to a NAS, I understand that SuperDuper! will not work with a NAS…

Thanks in advance.


SuperDuper! should be able to back up to a disk image stored on a NAS. You can not use a NAS volume itself (without a disk image) as the destination, but I personally think it would be a bad idea, even if you could. See page 18 of the manual. Make sure your NAS can support files larger than 4GB.

I also know that CCC can do the same. You can’t clone a volume to a NAS volume, but you can clone a volume to a folder or to a disk image. You can not back up your System volume to network storage, but that shouldn’t be an issue with modern versions of macOS, since backing up the System volume is no longer recommended in general. See also: Backing up to/from network volumes and other non-macOS-formatted volumes | Carbon Copy Cloner | Bombich Software

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If I just want to backup the files what solution is recommended?

I use Carbon Copy Cloner for backing up to a disk image on a Synology NAS. Works great. I recommend using the native Synology RAID format as it will be most supported by the device.

If it’s a small-ish number of files, I just use the Finder to drag/drop them to another volume (USB, network or other). If I want to keep files for an off-line archive, I will often burn them to a data DVD (a dual-layer disc can hold about 8GB).

For larger amounts of files, I’ll use CCC. You don’t have to clone a volume to another disk volume. You can also clone a folder to another folder, which can be very convenient at times.

I’d use Chronosync, very flexible, excellent tool for this kind of job.

Thanks Tommy. This sounds like a great solution as it is only the files I am interested in not the system. If there is a catastrophic failure in the RAID connected to my Mac Mini (e.g. two drives failing) is there a possibility of corrupt files being backed up?

Having done some additional research, when APFS first came out the advice was to use HFS+ on platter drives due to performance hits. Have Apple fixed this or is this advice still valid?

I would still recommend it for mechanical storage, like hard drives. Certain APFS features (including copy-on-write block semantics and multiple volumes sharing free space within a container) tend to create massive amounts of data fragmentation. This isn’t a performance killer on an SSD, but it is on mechanical storage.

I do use APFS on HDDs that are used for backups, because that use-case (large amounts of data written in one session) tends to minimize fragmentation, even when snapshots are used. But for devices that are going to have lots of random access (e.g. storage for documents and projects you’re actively working on), I think you’ll get better performance with HFS+.

For myself, the issue hasn’t come up because, aside from backups, all of my content is stored on my Mac’s internal SSD. I do have a portable USB HDD that I use for certain large projects that I need to transport to other computers, but because that drive needs to be used by Windows and Linux as well as macOS, I have it formatted as exFAT. (Normal FAT32 isn’t an option, because this project involves a VM, whose virtual disk image is far far larger than FAT32’s 4GB maximum file size.)