macOS backup for retrieving old deleted files

I have TM backups going back several years. Apple recommends a backup drive 2-3x your internal storage. How long that lasts depends mainly on how frequently you turn over data. If you download then delete lots of 4K video footage, that will fill up your backup faster. A full backup means TM starts deleting older data.

As for the method, you can stand up a Time Machine server using a Mac as a TM server with an external drive connected to it. Personally, I use an NAS as my primary backup. Ideally, choose one that offers turnkey support for Time Machine out of the box, both Synology (setup instructions) and QNAP (setup instructions) do so. But I also use a pair of SSDs as secondary’s backups, so I can swap one offsite weekly. A commonly recommended strategy is 3-2-1 where you have three copies of your data, two of which are backups and one of which is stored offsite.

First off, Tine Machine is not an archival backup solution. While it should maintain all deleted files assuming enough space, you should never assume it contains anything more that what is currently on your Mac. If you need an archive, I’d use Carbon Copy Cloner.

If you can’t go back in time, try running First Aid on the backup drive. You may have to disassociate it from Time Machine to check it

Time Machine works quite well, though the depth of the backups comes from having sufficient capacity available in the archives. If the archives are smaller, then the older backups will age out and purge out faster.

If you’re going to be poking st the archival storage often, using an SSD will work faster than a hard disk. But more costs, as SSD capacity costs more.

You could certainly do snapshots and rotate those to get deeper backups and offline backups, though that’ll mean more storage devices, and manual cycling among the connected and disconnected devices.

If you have multiple Macs, I’d look at a NAS. That pools the storage, and also performs backups without needing to cable to the backup device when the Mac laptop is connected to the same Wi-Fi as the NAS.

If you pick NAS, the NAS must support Time Machine server.

Some related info: Time Machine and Time Capsule replacement - Apple Community

Multiple Time Machine archives works well, and mixing those with periodic snapshots and maybe with snapshots offsite works well. Various NAS boxes dan support offsite replication, too.

One of the simpler is Ubquiti UNAS, which can also serve as a gateway into Ubiquiti networking. Probably the two-bay here, maybe the four bay. Synology works well too, but does have more knobs, and more capabilities. The previous link here has some vendors.

The NAS Compares website and YouTube channel might help with some background, too.

I have a Synology DS223j with a pair of 10 TB HDDs in RAID1 (so two copies of everything). I back up 5 Macs in the house to that, separate volumes/shares for each sized at 2x internal storage, with the remainder as a general file share. Been using that NAS for close to 3 years, currently about 5.5 TB used of the available 9.6 TB (formatted).