Sunday, June 15, 2008

Bulletproof Backups with the ReadyNAS Duo

Update: I wrote up my findings, four years on, in this new blog post!

I just invested in a ReadyNAS Duo, which is a mean-looking little device:

It's small (smaller than a shoebox), quiet (about as loud as a fridge), got terabytes of storage and can run autonomously doing all kinds of things (FTPing files, hosting web sites, downloading BitTorrents, etc.).

It's so flexible infact, there seems to be a lot of confusion on the forums around which strategy to adopt to make best use of it. So I thought I'd write this quick blog on how I use it as a really good backup device.

Step 1: Don't Use It

Well, don't use it as your main hard disk drive (HDD) anyway. It's tempting to try and move all your important files onto it, so that if your PC dies you can just hook up a different PC and off you go. But networks are much, much slower than local HDDs and it just isn't practical. Even e-mail programs run sluggishly if you're serving their EXE over the network.

Instead, get a good mirroring program like MirrorFolder, and have it mirror your HDD to the ReadyNAS frequently (even in real-time, if you like).

Step 2: Rely on it

Expect your PC to fail. Create a separate partition on your local HDD and call it something distant from C: (like N:). Then move all your important programs to it and configure them to be running off N: drive. This can be a tedious process, but once it's done your entire environment is relative to N:, which means as (and when) your PC fails, you can hook up another PC, map drive N: to the ReadyNAS and be up and running again nearly instantly.

Of course, it'll be slow (see Step 1), so ultimately you'll want to copy everything back to the 'mirrored partition' model on that new PC, but if your old PC dies and you need to continue working immediately for, say, the rest of the day it should suffice.

Step 3: Trick the software

Oddly, the ReadyNas Duo's weak spot is its backup software. You can't do weekly backups, or monthly backups, you can't filter out file types etc. etc.

Most suggestions on the forums are to work around this using some 'real' backup software instead, but that's silly because then it ties up your PC again while doing the backup. Instead:
  1. configure MirrorFolder (or equivalent) to only mirror the files you want to backup
  2. configure the ReadyNAS' built-in backup software to copy everything from the mirror into the backup share (this bit doesn't involve your PC, so you can run it overnight)
  3. set up different backup jobs, one for each day of the week, that backs up the mirror to different folders each day. You now have a rolling seven day backup
  4. create another backup job that, on Saturday, takes Sunday's backup and copies it to yet another folder (called, say 'Last Sunday')
  5. create yet another backup job that, on Friday, takes 'Last Sunday's backup and copies it to yet another folder (called, say 'Sunday Before Last'). Keep doing this so that you get monthly backups

Step 4: Trust nothing

Of course, even though your ReadyNAS is a secure backup of your PC, if you lose both at the same time you're still screwed. I'd recommend keeping the ReadyNAS in a separate part of the house to your PC, so that it's not lost in the event of a localized fire. But if the entire house burns to the ground, that's no help. Some of the forum backup strategies say 'buy another NAS' but there's a much nicer way:

The ReadyNAS Duo has 'swappable RAID', whereby you can swap one of the HDDs and the ReadyNAS will resync it. This feature is meant for when one of the HDDs is about to fail.

But you can also use it for off-site backups!

Invest in a third HDD and NAS drive tray (yes, you buy them separately if you hunt about a bit - the ones for the ReadyNAS NV+ are compatible). Then, on a weekly/monthly basis, swap one of the drives. Because you buy a third tray, you can leave the HDD screwed into the tray, so swapping takes very little time.Take the HDD you took out and keep it off-site. Now, even if your house burns down, you're covered!

Update - I've been advised there are problems with this style of swapping:

  1. Apparently both the SATA connectors on the drives and the ones inside the ReadyNAS are quite fragile, and likely to break with repeated swapping.
  2. If the drive is being written to as you swap it, those files might not be written correctly. Best to power the ReadyNAS down before doing the swap.

Instead, you can buy a USB enclosure for your extra HDD and backup over USB. Two things to note with this approach:

  1. If your USB enclosure is anything like mine, you have to unscrew it to put the HDD in. When you do this, you get to see just how flimsy the SATA connectors are!
  2. This is not a good solution if you have a serious amount of data. Re-syncing a 500GB HDD with RAID-X takes about an hour. With USB it'd take days.


network games said...

I like my duo, its fast and was easy to install, but the fan... very noisy.

Anonymous said...

Have you ever had a failure and had to recover data from your 3rd disk? Did it work?

Richard said...


The data is definitely on the 3rd disk, so I don't anticipate a problem (I could just use it as a stand-alone HDD), but it's fair to say I haven't yet needed to recover using it.



Billinge said...

My understanding is that the Netgear ReadyNAS uses different formatting of data to standard pc's so it may not be straight forward to plug the 3rd drive into a pc.
I'd love someone to correct me if I am wrong.
Also when a new dick is installed in the drive it is formatted in readiness for receiving data from an existing drive.

Richard said...

This is a good point. I think the ReadyNAS uses Ext3 formatting. While this is different to PCs, it is at least industry standard (albeit the Linux industry) and not proprietary to ReadyNAS or anything.

So while PCs can't read Ext3 drives directly (as far as I know) there do appear to be Windows tools that can do it.

Anonymous said...

Are you insane - you are using RAID driving mirroring to create shadow copies - something people laugh at in the industry... At the point of removal you are risking blowing both drives. You should use the backup service in the Readynas to backup offsite directly, or to backup to an external USB hard-drive... Ignore this rubbish!

Andrew said...

Another great program that was written out of frustration with the supplied NTI backup software is Quickshadow by QuicklyTech. It's a great app. I'm not the author but I am a big fan of it.

Mitch brown said...

Hi mate,
I have a readyNas NV+ as a local storage device for my graphic designers. the rest of my users are using a different file server this file server is backed up to a data centre. what i'm looking to do is backup my readynas NV+ to the file server so that there is an offsite back up of the data on the readynas. I know this sounds stupid and i might as well just have all my data on the one file server but unfortunately it would bring the users world crashing down because the idea of working from a different directory would perplex them.
Can you offer any advise?

Richard said...

Mitch: have you looked in to ReadyNAS Vault?

Unknown said...

If anyone is looking for extra trays, I found these ones listed below by searching for 'RND4TRAY1-10000S'

Great article by the way, very helpful.

Gareth Williams said...

Did you have to reformat the drive you were about to put in each time?
Also, any issue with hot swapping like this yet? ...usb backups don't seem to work for me! Feedback from Duo seems really vague.

Richard said...


No I do not have to reformat the drive. The ReadyNAS takes a while to 're-sync', but then it is fine.

And no, I have had no problems so far. I just turn the unit off and swap carefully (so as not to damage the connectors).

But that's just me. Your mileage may vary :)


Gareth said...

New tray and drive for me then!
Many thanks for the article and feedback.

Gareth said...

...a couple of months on and everything going well; thanks for the advice!

Anonymous said...

Anyone know good software to do backup from this NAS? im getting issues as not picking up external drivers.