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I want a failproof backup scheme for my home business. This is the scheme i have come up with so far:

  • Workstation:

    C:\ SSD Drive 1: for OS
    D:\ SSD Drive 2: for Current Projects
  • NAS

    L:\ HDD Drive 1: Libraries and components        
    I:\ HDD Drive 1: Incremental backups (Of Working projects)
    R:\ HDD Drive 1: Archive (archived projects, data etc + Incremental)
    X:\ HDD Drive 2: Copy of Libraries and components        
    Y:\ HDD Drive 2: Copy of Incremental backups         
    Z:\ HDD Drive 2: Copy of Archive 

So the second hard drive in the NAS is just a synced or RAIDED copy of the first drive. The whole idea is to have a THIRD NAS DRIVE, which is also a copy of the first NAS drive. This third drive is kept at a friends home. Every week, I'll take out the updated NAS drive, switch it with the old one my friend has, install the old one in the NAS, and update it again.

As far as I know, this will guard against every possible failure:

  • Disk failure / accidental overwrite: Use inceremntal backups
  • Theft / Fire : Use the Disk at friends home

Now my question :

I've never used a NAS or RAID. Is it even possible to switch the drives as described above ?? Also, should I manually sync the drive with special software, or use RAID to sync the 2 drives ?

EDIT: First of all, don't go NAS because its TOO SLOW (Network!?). Secondly, don't use RAID.

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up vote 6 down vote accepted

Normally the way this is done is something like this:

1) Raid array with 1 or more redundant drives (so raid 5 or 6) - allowing one or two drives to fail at once without data loss. Sometimes this is done with Raid 10 which is effectively two arrays, you can lose more drives, but only if they're from diffrent arrays. Given the rest of the scheme 5 or 6 should be ok. It depends how much data, costs, performance requirements etc.

2) Offsite backup: Basically take a full copy of the data and store elsewhere.

Regarding theft, you need to allow for the data's security, so the offsite backup at least should use full disk encryption (if applicable).

Regarding your current setup (and the proposed) do you need to allow for accidental deletes ? You need to make sure removing a file wont automatically remove it from all your other copies. Same goes for file corruption.

If you use raid 1 (ie mirroring) it should be possible to swap drives out and automatically sync the data, but personally i wouldnt do this for the previous paragraphs reasons. What i'd do (and in fact do) is use raid 5 to aid in hardware failures, take a manual copy once a month which stays on site, and an encrypted copy once every 3 months which goes off site. If my data was super important, id likely go with raid 10 rather than 5, but restore times arnt an issue for me.

re: restore times. Having the entire array offsite on an encrypted drive is ok, but can you afford the downtime to restore it ?

As for swapping drives, I use a case which holds the drives and has a slot in it which takes a sata drive. Pop it in, do the backup, and hit the eject button. done! sata drives are handy like that as you can hot swap them.

Overall, i'd say your incremental backup approach, combined with raid 5 and an offsite (maybe encrpyted) would be good enough. But practice raid skills on a virtual machine or similar, as if you need it you may really need it.

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+10 for the offsite if I could – Cry Havok Nov 3 '10 at 13:01
What's the advantage of the RAID5 array ? – Run CMD Nov 3 '10 at 14:18
raid 5 (and 5 specifically) splits the data over several physcial drives. It does so in such a way that there is an excess of data stored, and that all parts of the data are avaliable on two drives. This means if a drive fails, you lose no data and can recover and continue working. One thing to allow for though is that rebuilding puts strain on disks, so may cause other drives to fail - and you lose 1 drive's worth of space (3 1TB drives gives 2TB usable space). This raid functionality is called striping – Sirex Nov 3 '10 at 15:17
And with raid 5 (which uses one parity disk, you can lose only one drive before data is lost. raid 6 uses two partiy drives, so you can lose 2 drives at the same time and be ok, but you lose 2 drive's of space, similar raid 5. – Sirex Nov 3 '10 at 15:19
Great answer. I'd avoid RAID 5 though if they are large disks with lots of TBs of data. – MK Jul 1 '15 at 21:55

Some potential failure modes:

  • Swapping disks causes a disk failure.
  • Swapping an old mirror disk back in causes the mirror to update with the older member (losing all current data)
  • Backups succeed without apparent error for weeks, after which time you find that you replaced a critical file with a cute picture of a squirrel by accident.
  • One of the drives dies due to travel.
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+100 for nr 2 .. Did that ever happen to you? – Run CMD Nov 3 '10 at 22:56
Nope. Too paranoid about #1 / #2 to have tried it. Maybe the drive states are versioned and it couldn't happen. Maybe. – Slartibartfast Nov 5 '10 at 3:10

Or, alternatively something similar to the ioSafe SoloPRO may fit your needs, although this particular product does not have RAID or NAS capabilities.

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Thanks for the reference. This doesn't seem 100% failproof though ... what if a burglar steals your fireproof box?? – Run CMD Nov 3 '10 at 14:09
that is where the Kensington lock comes into play. The idea is make it too difficult for a "casual" burglar to take it. Anyone more determined will get what they came for regardless of what measures you take (off-site backups included). – Xantec Nov 3 '10 at 14:19
OK, but if I'm a burglar and i see something with a lock on it, I expect it to contain something valuable, even if i don't know what it is ... And if I'm a tiger kidnapper or whatever :-) I will want you to open the lock. The chance of a burglary in 2 different homes at the same time seems almost non-existent to me ... – Run CMD Nov 3 '10 at 14:30
A random burglar carrying a set of bolt cutters with them, on the off chance that they'll find something chained up that they want, seems equally unlikely to me. Chances are if they come with cutting hardware they've picked you out for a reason, which if that reason is your data then they'll probably know about your off site backup; fwiw. – Xantec Nov 3 '10 at 15:02
Maybe you need to allow for how they break in in the first place ? Locked back gate ? -- They'll have bolt cutters with them. Its fairly common in household burgularies, more or less. – Sirex Nov 3 '10 at 15:21

With the ubiquity of relatively inexpensive services like Jungle Disk or Drop Box, why not consider adding them to your backup strategy? They're clearly offsite and probably more reliably available than your friend(s). (What happens if no one is home at your friend's and you need access to a file?) Jungle Disk and Drop Box can also be accessed from any where.

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Thanks, this was our first idea too. But since sometimes we deal with large files (+1GB), and the speed of such an online service is defined by your internet connection UPLOAD speed, this doesn't seem a good idea performance-wise ... – Run CMD Nov 3 '10 at 14:11
I haven't checked, but I would think a service like Jungle Disk would offer incremental backups. Jungle Disk does charge by the amount of data transferred, so transferring incremental changes would make sense to keep your bill low. Of course, if you are constantly creating new +1GB files then incremental backups don't benefit you. – Mike Chess Nov 3 '10 at 19:49

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