SnapperTalk

So you have your shiny new RAID-1 or RAID-5 system with all your photos mirrored on both drives, and you’re feeling pretty safe… right? Wrong. Go back and read the list of corruption and human-error causes of data-loss on Page 1.

Yes, your RAID-1 or RAID-5 volume protects you very well against a drive failing, and that’s good. But it’s important to understand the differences between mirroring and backing-up. The RAID-1 mirror means if a drive fails you won’t lose even your very latest work or changes through a drive failure. But to counter the risk of data-loss through corruption or human error you need to be able to “go back” to before the error was made, and for this you need a backup strategy.

How to Back up

There’s a plethora of different backup software out there, and much information on the net about the merits of each, so I’m just going to focus on what I like, and for MacOSX, because that’s what I use.

Carbon Copy Cloner: This is an excellent and free (donations are welcomed) utility for MacOSX that lets you create a bit-for-bit copy of one volume or folder, to another volume or folder. Also great for backing up your system drive as it is able to create bootable backups.

Deja-Vu: If you just want easy, hassle-free, backups, Deja-Vu is a reasonably priced (full-feature trial available) preference-pane for MacOSX that runs in the background and can create scheduled or manual backups, snapshots, incremental backups and much more.

Retrospect: This is truly the king of backup software and available for Macintosh and Windows. Initially it may seem hard to configure, but with a little time you’ll realise just how powerful this application is. Supports many backup modes such as normal backup, incremental/progressive backup, duplication, network backup etc. You can install a small Retrospect “client” on all your networked machines, both Macs and PCs, and have the main application create automatic backups of all the machines each time they are connected to the network. Compressed and/or encrypted backups are also possible, although if your archive consists mainly of JPEGs there’s no point in using compression. Very powerful.

An example backup system

Everyone’s needs will vary, but in my mind a very good setup would be a RAID-1 or RAID-5 volume backed up to a single external hard-drive.

Maybe something like this: 2×500GB drives mirrored in a RAID-1 setup providing 500GB of storage, backed up to an external 500GB single drive on a daily/weekly/monthly basis. This way if either of the RAID drives fail you won’t have lost your latest files. And if files get deleted or corrupted on either the RAID volume or the external disk, you can get the good files from the other volume and copy them back. I would recommend an incremental/progressive backup with snapshots, so that only the newly-changed or created files get copied on each new backup, so the backup is both quick AND you can go back to how the drive’s files were at any given time in the past. That way if a file gets corrupted or deleted on the original disk (e.g. the RAID volume) you can go to the external disk and pull off the version of the file as it was e.g. three months ago when it was fine.

Next page: 4. Hard-drive interfaces
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