Thursday, 4 April 2013

A NAS rides to the rescue.

For those who think they don't need backup or can't be bothered or one backup is enough here is a little tale to hopefully make you think again. A NAS is simply a network connected storage box (Network Accessible Storage). Stick some drives in a box give it a bit of an operating system and a network card and charge lots of money for it.

I'm upgrading my main PC and network and have recently stuck a couple of brand new 2TB drives in a NAS box and set it up as a mirrored drive ie. even though I have 2 x 2Tb it sees it as 1 x 2TB and mirrors everything on the first drive onto the second. This means that either drive in the NAS can fail and I still have all my data and can stick a new drive in and the NAS will rebuild the data on the new drive and leave me with nicely mirrored one volume two drives set up again.

Righto, so being a Yorkshire man and sometimes a bit tight. I decided that what I should do (as I have the data on my PC as well) is convert the NAS to a single drive and no mirror and use the drive this would release from the NAS for my new PC build.

Not as straight forward as it would sound as to do this you have to convert the RAID volume on the NAS back to a Basic non RAID volume. Easy enough to do though. As I had all the data on my PC it was just a matter of taking the 2nd drive from the NAS box and repartitioning the remaining drive as a Basic volume. This erases all the data on the drive but not a problem as I have it all on my PC and just need to copy it back on to the now single drive on the NAS. All fine in theory. That is until the drive on the PC packs up half way through writing the data back to the NAS. The chances of it happening are probably small but that is exactly what happened. So, now I have corrupt data on the NAS and a dying disk with corrupt data in the PC. Pretty stuffed at that point you would think. Which is pretty much what I thought and was beating myself up for being a tight git.

But, but , but. Yes, there is a 'but' to this tale.

I built the new PC yesterday and decided (thank you God) that I would use another drive for the Operating System and once that was all installed only then would I use the drive that had come out of the NAS as the new data disk and I would copy the data back onto it from the NAS. But the NAS now has corrupted data on it. Aaaarrrgggghhhh. Was my first thought and my second. Swiftly followed by some choice words as a third and fourth set of thoughts.

Then I remembered something. Something deep and very important. All my data was still on the drive that had come out of the NAS and was still configured as a drive in a Raid array. Allleee blooody llluuulllaa. Now I could take the good drive (with corrupted data copied from the PC) out of the NAS box and put this drive back in and the NAS box would tell me that there was a disk failure but would use the data on this good RAID drive. All my data was safe and sound on the mirrored drive and all I now had to do was stick the drive back in the NAS box that I had converted to a Basic partition and the NAS would rebuild the mirrored RAID onto this drive.

The NAS is chugging away rebuilding the data on the 2nd drive and in a couple of hours I will be back to where I was a few days ago with a mirrored two disk RAID on the NAS. I think I'll keep it like that and invest in a new drive for the new PC.