Yes, a Mac can back up to a NAS with Time Machine, provided the NAS shares a folder over SMB and you give that folder its own user and a size quota. Apple confirms that Time Machine works with third-party network storage that supports Time Machine over SMB, and this guide walks through the setup on a Synology, the checks that fix most failed backups, and the point where a NAS backup stops being enough on its own.
We are Macwest Data Recovery & Mac Repair, a Los Angeles lab serving West LA, Santa Monica and Beverly Hills since 2006. Most of what follows comes from the other side of the bench: the Macs and NAS units that arrive after a backup plan quietly failed.
It can, and it is a sound arrangement for a household or small office with several Macs. Apple’s documentation lists a directly connected drive or a NAS that supports Time Machine over SMB as valid destinations and recommends SMB when both SMB and AFP are offered.
The practical trade-offs against a drive plugged into the Mac are these:
| Factor | NAS over the network | Direct-attached (DAS) drive |
|---|---|---|
| Number of Macs served | Many, from one box | One Mac per drive, usually |
| Backup speed | Limited by Wi-Fi or Ethernet, slower first run | Limited by the port, usually faster |
| Backups when away from home | Only on the same network or by VPN | Whenever the drive is connected |
| Built-in redundancy | Yes, with RAID 1, 5 or similar | None unless you add it |
| Typical failure | Network, SMB or permissions errors | Drive failure or unplugged cable |
| Cost per Mac | Lower with several Macs | Lower with one Mac |
If you have one laptop that travels, a DAS drive is simpler. If you have two or more Macs and a desk where Ethernet is available, a NAS is the better fit.
Synology’s own Time Machine tutorial says to create a shared folder, enable SMB and give a DSM user read/write permission on that folder. Menu names shift slightly between DSM versions, so use the steps below as the sequence and the Synology page as the reference.
In DSM, create a new shared folder used only for Time Machine, for example “TimeMachine”. Keep it separate from your photos, documents and media. A dedicated folder lets you cap its size without touching anything else.
Add a DSM user such as “tmbackup” with read/write permission on that folder and no access elsewhere. Using a restricted account means a compromised Mac login cannot reach the rest of the NAS.
Turn on the SMB service in the file services settings, then enable Bonjour broadcasting for Time Machine on the shared folder so Macs can discover it. Synology describes the Bonjour and SMB settings for the backup target on the same page.
Without a limit, Time Machine keeps growing until the volume is full, which also starves your other shares. Synology’s backup solution guide recommends a size limit on the Time Machine folder for exactly this reason. Use the two-to-three-times rule: a 1 TB Mac gets a 2 to 3 TB quota.
On the Mac, open System Settings, go to General, then Time Machine, and add a backup disk. Choose the NAS share, sign in with the backup user, and decide whether to encrypt the backup. Encryption is worth turning on for a laptop that holds client files, and you must store the password somewhere other than that Mac.
Plug the Mac into Ethernet, keep it awake and let the first backup finish. After that, Time Machine only copies files changed since the last run. By default it keeps hourly backups for the past 24 hours, daily backups for the past month and weekly backups for earlier months, and deletes the oldest ones when the disk fills.
The logic is identical on any brand: a share that speaks SMB, a dedicated account, a size limit and Time Machine support switched on. The menu names differ. Apple’s requirement is the constant: the NAS must support Time Machine over SMB, and AFP is the legacy path to avoid.
Time Machine backs up your apps, music, photos, email and documents, and it can restore older versions of files and ones you have deleted, according to Apple’s overview. It is not a complete record of everything, though:
Open the exclusion list under Time Machine options once after setup. Developers often exclude large folders such as virtual machine images or caches, and they forget they did.
The two tools do different jobs, and many people end up using both. Time Machine is versioned: it archives older copies of files so you can go back in time. Cloning software such as Carbon Copy Cloner makes a copy of a volume that you can use for migration or as a replacement drive. Macworld cautions that a straightforward clone does not let you go backward, so you should keep other forms of backup.
| Question | Time Machine | Cloning tool (such as CCC) |
|---|---|---|
| Main purpose | Versioned history and file-level restore | A copy of a volume for replacement or migration |
| Can recover a file you deleted last week | Yes, if still retained | Only if the clone has not yet overwritten it |
| Best destination | NAS or external drive | Directly attached drive, or a network volume |
| Setup effort | Minutes | Task configuration |
| Cost | Included with macOS | Paid software |
The sensible split: Time Machine to the NAS for history, a periodic clone to a separate drive for fast recovery. Do not put both on the same physical disk. Macworld’s Glenn Fleishman argues for dissimilar backups on separate media, since one drive failure, theft or disaster would otherwise take both.
Most failures come from a short list of causes. Synology’s troubleshooting page points to the NAS configuration and free space, the Mac and NAS being on the same local network and connected via SMB3, and security software interference. If it still fails, collect the Time Machine logs in Terminal before you change anything else.
Work through the checks in this order:
The classic symptom is a message that the sparsebundle disk image could not be accessed. That usually means a permissions, space or connection problem rather than a damaged Mac. Our own Time Machine stuck checklist covers the Mac-side checks in more detail.
| Symptom | Likely cause | First check |
|---|---|---|
| “Connecting to backup disk” never finishes | Network or SMB negotiation | Same LAN, SMB3 enabled |
| Sparsebundle could not be accessed | Permissions, quota or interrupted run | User rights, free space |
| Backup starts then stalls | Security software or sleep | Pause antivirus, keep Mac awake |
| “Not enough space” despite free NAS space | Quota too small | Raise the folder quota |
| NAS not visible | Bonjour broadcasting off | Re-enable Time Machine on the share |
Stop all disk writes immediately. Do not keep running Time Machine, do not initialize a volume, and do not rebuild a degraded array to “see if it comes back.” Every write can overwrite the blocks you need.
What to do depends on which side failed:
A NAS is a single device in a single room. A fire, theft, power surge or ransomware event hits the Mac and its backup together. The common safeguard is the 3-2-1 rule: at least three copies of your data, on two different types of media, with one copy offsite. The rule is described in a widely cited Time Machine deep dive that also warns relying only on Time Machine will eventually fail.
A reasonable layout for a West LA home office:
On the NAS itself, use RAID for uptime and snapshots for accidental deletion, but treat neither as a backup. Synology says snapshots use little extra storage and that High Availability can replicate data to a passive server that takes over if the active one fails. Those features are for larger deployments. For a home or small office, a second copy on different hardware is the cheaper step.
For more habits worth adopting, see our Mac data loss prevention guide and why Macs need backup.
In nearly twenty years of Mac and RAID recovery work in Los Angeles, the pattern is consistent. The people who lose data are rarely people with no backup. They are people with a backup that stopped running months ago, was set up with a quota that quietly filled, or lived on the same device that failed.
Our advice is to test a restore the day you finish setup: pick a document, restore an older version, and confirm you can open it. Check the Time Machine status once a month. Keep the NAS’s disks and the Mac’s SSD healthy, and replace NAS drives of the same age on a schedule rather than one at a time after each fails, since matched drives tend to fail close together.
We would rather you never need us. But when a logic board will not power on, when an APFS volume refuses to mount, or when a RAID 5 has lost two members, component-level repair and forensic imaging are what recover the files, and we do that in-house at our lab on Wilshire Boulevard.
— Kaya
If your Mac, external drive, NAS or RAID array has stopped responding, we offer free diagnostics and a no recovery, no charge policy, with same-day appointments available. You can review our data recovery services, our RAID recovery work, or our Mac repair service for logic board, liquid damage, screen and battery problems.
We are at 12041 Wilshire Blvd, Ste 26, between the 405 and Santa Monica, near UCLA and the Getty Center, and we serve Westwood, Brentwood, Santa Monica, Beverly Hills, Venice, Hollywood and Culver City. Call (310) 866-0828 to book.
No. The NAS must support Time Machine over SMB. Apple recommends SMB over AFP, and AFP transfers to or from NAS devices are unsupported in macOS 27 or later. Check your NAS vendor’s documentation for Time Machine support before buying.
Synology recommends a quota of at least two to three times the Mac drive or the data being backed up. A 500 GB Mac therefore needs roughly 1 to 1.5 TB. Setting a quota also keeps Time Machine from filling the whole volume.
It depends on how many Macs you have and where they work. A NAS serves several Macs and can add RAID redundancy, but backups run only on the local network. A directly attached drive is faster and simpler for a single laptop.
It does not back up system files or apps installed during macOS installation, and files on its exclusion list are skipped. In rare cases, settings in non-Apple software can also keep files from being backed up. Review the exclusion list after setup.
Stop all disk writes immediately and power the device down. Do not rebuild an array or initialize a drive. Then call a recovery lab: we offer free diagnostics and same-day appointments in West LA at (310) 866-0828.
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