Add 2 USB hard drive to a WD MyCloud Mirror 24/7

Good morning,

I would like to add more space to my MyCloud Mirror by using 2 USB hard drives. Is it “safe” to use a 2.5" one attached 24/7 for backup purpose?

Depends what you mean by “safe”.

I’ve got 2 HD’s hanging off my MCM (a 5TB WD Elements and a 1TB Seagate) and both are quite happy, going to sleep if they’re not used and waking up fine if they are accessed (although that does of course cause a minor pause in access times, as you would expect). The 5TB is the main source for my Pi Kodi media player, with my backups going onto drive 1 of the MCM itself.

But as far as the outside world is concerned, both drives just appear as shares from the MCM, and are treated accordingly. So there should be no issue to use it as a back-up target, as far as Smartware is concerned it’s just another share on the MCM. You just need to be careful not to accidentally unplug it (either physically or via the dashboard’s USB options).

The only thing you can’t do is include them in RAID arrays from the MCM itself, that can only be done with the two internal drives. But for general expansion it should be fine, based on my own experiences.

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Great, thank you very much for your reply!

This is nearly the same setup I would like to realise.

Regarding the above - practically, as a user, it means that for one to have redundancy one should include those files on the internal drives, e.g. the core data that one needs to ensure protection for a typical NAS use-case

And use the expanded drives on the USB ports for general data store - like you mentioned above to store backups for one/more of PCs on the network.

Did I understand correctly ?

And that leaves the open question - what to do / how to scale when the internal RAID store starts hitting close to full capacity ? One obvious solution is to buy a new one with higher capacity - say 12TB (2x6TB) if you had 8TB (2x4TB) originally - and migrate to the newer one. Any other option to scale for tech. savvy person ?

Last Q - I have a WD myBookLive - it has a Ethernet connectivity alone (no USB) - is there a way I could connect it to myCloud mirror ? Cannot see an obvious way. If all else fails it means I end up with two isolated entities - one myCloud Mirror with possible USB expansion drives, and another myBookLive. But would really like to consolidate myBookLive with myCloud mirror if it is reasonably feasible.

Thx !

@csdhruv - yes, your understanding sounds correct. It makes sense to exclude USB drives from RAID arrays, as of course for any RAID array the drives need to be permanently connected, and that’s one thing that you cannot guarantee with USB ones. So yes you can have the fitted internal drives as RAID0 or RAID1, then either use the USB drives as just separate general networked storage (as they will appear as separate shares) or as backups either by manual or automated copy.

For upgrading, the options are the two you mention. Either replace the drives with larger ones or get a new box. It’s where things like the EX4 have the edge, as they can take more drives at once. It’s one of those things where it pays to plan ahead and be as future-proof as you can (what you’ll need and also what you can afford).

And for the MBL, there is no way to link the two. They will always be distinct entities, although of course they can co-exist happily side by side on the same network.

Awesome - thx for confirming my understanding !

Regarding the above - in future if we want to replace the HDD with a larger one ( MCM manual instructs us how to do so), I’d imagine there sure would be a way to mirror all data from the older-smaller capacity-drive to the newer-larger-capacity drive. Does WD provide tools to do that - sorry if this sounds trivial Q - but am relatively new to WD tools.


If you’re in RAID1, it’s a case of just shutting down the MCM and swapping one of the drives to the new blank larger one. When you restart, if you have auto-rebuild enabled then the content of the original drive will automatically be copied onto the new one. If you don’t (you have it set to manual rebuild) then you have to go into the dashboard and press the rebuild button.

Those settings are in the config settings when RAID1 is selected (under Storage > RAID on the dashboard).