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Similar to this question from 2.5 years ago, so I wanted to ask a similar question for how to backup a larger amount of data at low cost using today's available tools.

I have a home server running windows 7 with a 6 TB raid 5 where I store several TB of media files. Far too much data for Amazon S3 or any online solution. Disks are cheap, but single disks don't come in sizes larger than 3TB. Is there a free or cheap backup tool which would backup my raid volume across multiple physical disks? I don't need the OS, just the data files which are on a disk which is separate from the OS drive. Looking for something cheap because I don't want to spend lots on a home solution.

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You want to just backup everything (=have a copy), or to have partial backups, or to have snapshots? Is your data already organized in someway (directories) or do you use some program to do that? – woliveirajr Sep 22 '11 at 16:28
The data is organized into windows directories, so there is some structure. I don't need to access the data in its backed-up state, except for a restore of the whole volume of data. – steampowered Sep 22 '11 at 17:26
I know it's bad practice to consider the redundant part of the RAID as a backup, but it's a cheap and automatic way in your situation. Alternatively, use symbolic links/junctions in Windows to arrange all the files you want to backup to a single directory and use some file syncing tools to do the backup. I personally use GoodSync, but xcopy will do in simple cases. – Sep 22 '11 at 17:35

If I understand your situation correctly, the home server with the several disks holds your production data, and you ask how to back that server up.

If you have even a basic level of Linux knowledge, I'd suggest that you build a small Linux box with as many hard drives as you need, configuring them as a software RAID, and use BackupPC to do the actual backups.

This solution, which I have practical experience with, will be

  • comparatively cheap, because the software is free, you'd have to buy the HDDs anyway and small barebone systems are in the same price range as NAS boxes
  • energy efficient, as you can power the box up using a BIOS wakeup timer and shut it down using a script as soon as the backup is done
  • easy to extend with more capacity
  • offer safe (encrypted and authenticated) transport over the network

The reason I suggest a completely separate machine instead of more drives in your existing server is that that approach will also offer some protection against hardware failures in your existing machine. A typical problem that can kill off all drives in a computer is overvoltage from a defective PSU or lightning.

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I tried to make the primary box a unix server using Ubuntu 10.04 a while back, but it was so difficult to make a non-operating system software raid. Ubuntu has a great solution for building a primary raid disk during install, but mounting additional disks in software raid is a pain. I have no problem using a pre-built unix server, but I won't take time to battle hardware and build a complex unix box. Plus, the raid would need to allow for online raid level migration to add disks as the data expands, and I think this would take lots of time in an Ubuntu software raid, given my experiences. – steampowered Sep 22 '11 at 17:40
I agree that it's not intuitive, especially since that's nothing one does every day. But growing the array worked for me (when I tested it on my backup box) with four or five commands, which I researched once and just wrote down :-) Also, there's no need for RAID level migration. -- However, if you don't feel comfortable doing it this way, then don't. Backups are too important for experiments. – jstarek Sep 22 '11 at 17:47
I miss-spoke when I said "online raid level migration," I meant online capacity expansion. – steampowered Sep 22 '11 at 23:55
up vote 1 down vote accepted

It turns out many backup products, both free and paid, allow the user to use multiple backup disks to accomplish backing up a large raid onto several smaller disks. But this is considered a basic feature, so many don't list the feature except in the manual. When a backup disk fills up, my product asks me to insert a new hard disk, and then it continues on the newly inserted disk. Restoring is accomplished by inserting the disks in sequence as the restore proceeds.

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I know this is 4 years late, but I'm curious which product you used? I have exactly the same requirements that you have, except we're using a Mac Mini as the server and I'm investigating all my options. – Rystraum Jul 16 '15 at 6:07
I use this – steampowered Jul 16 '15 at 18:52
Thank you for the reply! :) – Rystraum Jul 20 '15 at 17:40

You could try Acronis True Image Home 2012, I'm not sure if it will allow backup over multiple external drives, but you may be able to if you also get the Disk Director. But if it doesn't you can backup individual files and folders, or groups of files and folders. So you could have multiple drives, and multiple backup jobs set to backup different groups of files and folders. For example, if you have 6 TB of files, and two 3TB external drives, you would setup two backup jobs each backing up half of your files. True Image Home 2012 will run you about $50. For signifigantly higher cost you could purchase a DataRobotics (Drobo) unit which is a stand-alone external storage unit that you install standard SATA drives into and then Drobo creates a partition, so you can have what ammounts to an "external drive" with much more than 3 TB of space. It can be connected to your computer using eSATA, USB, or Firewire, and then you could use acronis to create a single large image on the single large partion. These systems including drives can be in the $2000+ range though. See below for websites. Hope that helps!

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If you have unix utilities available, you could script this out using tar and split. You can create the initial tar file and then split it to the size required to fit on external disks. This may not be as full featured of a backup solution as you are looking for, but it does fit your requirements for cheap. The only cost will be the drives you purchase. If using external disks, you also have the benefit of being able to take them offsite.

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