First published on my other blog www.stumblingpast.wordpress.com 20/12/2010.
Computer backup is vital. This was brought home to me when we suffered the Great Perkins Computer Glitch of 2010. Every computer directory that contained my work for the last year disappeared, including all my research for my thesis. Yes, it vanished! I was having trouble opening a directory; we left it to watch a movie and when we came back we could not see or access a single file. Fortunately my other half, Hubble, had set up not one, but two backup systems. Now we were to find out how good our backup systems really were….
For 24 hours Hubble and I worked on retrieving my lost files. Well, it was Hubble who did the work, I just explained my byzantine directory structure. As he is the expert I asked him to explain the problem and what he had to do to rectify the situation.
Perkinsy: What do you think caused my directories to disappear from view in windows explorer and all other software?
Hubble: Hard disk drives are organized into a series of platters (like CDs stacked on top of each other), each platter is broken up into sectors and tracks. Tracks are concentric circles and sectors are like pizza slices (wedges). Every file is stored somewhere on one (or more) of the disk platters at the locations pinpointed by the track and sector. The diagram below shows that. Item D is a file spread across three sectors on one track.
The whereabouts of each file and directory is stored in a special file called the Master File Table (MFT). Sometimes the MFT can become corrupted and it no longer knows where to find the file on the hard disk. Even though the file remains on the disk, there is no way to get access to it. The same thing happens when you delete a file. In normal cases, deleting the file merely removes the entry from the MFT, but the file remains in place on the hard drive unless you go to extraordinary lengths to wipe the surface.
In our case, I believe the MFT became corrupted probably due to a power surge or something like that just as the hard drive was writing a file, and the MFT became troubled.
It is very important if you do lose a directory or file for whatever reason, whether it is deleted or lost due to a corruption, do NOT write anything to the hard drive until you can establish that you have tried everything. A professional can probably recover the data if you haven’t written anything else. The problem is that once you start saving changes to other things, the computer assumes that the space where your file is stored is no longer used, so it may decide to re-use the space. Once the file has been overwritten either partially or completely, you will have no way of recovering the file, so you have to act quickly or stop saving stuff.
Perkinsy: How common is this problem?
Hubble: It is quite rare. It has been years since I have seen this sort of problem. It can be much more common if the hard disk drive is beginning to fail, and typically people should consider replacing the hard disk drive if they see these kinds of problems – particularly if they happen more than once.
Perkinsy: Can you explain what backup facilities we use and the state of these backups when the problem occurred?
Hubble: Our personal backup system consists of two completely separate systems. The first is a self-managed local backup and the second is a cloud-managed automated system. Personally I think both are necessary for worry-free computing. And as it turned out, it was a good thing we had both.
The local backup consists of an external hard disk drive, plugged into the computer using a USB connection and running its own power supply. External hard disks can be purchased quite cheaply now on line: you can get a huge 2TB (2 Terabytes, 2000 Gigabytes) for around AUD$240 or less. Drives big enough for most people can be purchased for under AUD$100.
Paired with the local external hard drive is a piece of software designed to manage the backup. I use a tool called Backup4All which works well. You can set it up to automatically back up the computer on whatever time schedule you want. It compresses the files and stores incremental changes in little files, with occasional full backups, depending on how you have configured it.
If you want to really protect yourself, get two external hard drives and store one at a friend or neighbour’s house. Swap them over once a week or fortnight. That way if someone steals everything you have, then you are still pretty much covered.
The cloud based backup is very good. There are a number of ways of achieving this. Firstly, there are the various antivirus vendors who offer storage as an add-on to their service. This includes Symantec and McAfee, but I prefer to use a dedicated service. For about AUD$50 or AUD$60 a year, you get an unlimited amount of on-line storage. The tool I use is Carbonite, but there are others, including JungleDisk, Mozy to name a couple.
These tools are fantastic because they simply work in the background. The caveat is that you have to be careful with your ISP (Internet Service Provider) data plan. Many people have a dataplan that requires them to pay for upload as well as download data. Our plan is a download only plan so we can put the data up into the cloud without worrying about how much.
I am not at all concerned about privacy – the data is encrypted twice.
Perkinsy: What steps did you have to take to retrieve the backups?
Hubble: The first step was to check out the local backup. The local backup requires a little more hands on managing and I hadn’t been paying much attention, so I needed to check to see how it was all going. I had recently made a decision to have the machine shut down at night to save power, and had overlooked the fact that I had scheduled the automatic backup to happen at 3:00 AM. But the machine had not been on for a couple of weeks and so the backup was a couple of weeks old.
The first thing I had to do was to get as much from the hard drive as was there, but then find out what had changed in the past couple of weeks. For that I had to go to the on-line copy and look up what files had changed. This proved a bit of a challenge, but it was better than just copying everything down again – that would have been slow and potentially expensive. Do-able, but expensive.
Perkinsy: We had discussed our backup systems earlier in the year so all through this I had confidence that we would be able to retrieve my important files. Were you happy about the results of the retrieval from backups?
Hubble: I was happy that throughout the experience you were not at all stressed, which made it easier to deal with the problem in a clinical way, knowing that I would still have a bed to sleep in ! 🙂 Seriously though, there were a couple of minor aspects of the user interface that could have been easier, but on the whole it was a simple matter of identifying from both backup systems which files I wanted to retrieve and then pressing the relevant “recover” button.
Perkinsy: What type of system for backups would you recommend for writers working from home?
Hubble: The backup systems you choose will depend on how much value you place on your data.
The system I have outlined above with multiple external hard drives supported by a cloud-based backup is a very safe way to ensure that your precious data will be safe.
You can also have your computer set up with a mirrored hard drive so that you have two hard disks with the data being written to both simultaneously. It won’t help in the rare case described above.
The best advice is to ask yourself what would happen if you lost a certain file? If the answer is “not much”, then perhaps it doesn’t matter. But if the answer is “shock horror”, then you should have a combined strategy like the above.
In the old days we used to use a Grandfather, Father, Son routine where floppy disks or tapes were cycled on a daily, weekly, monthly basis. But these days, drives are so much bigger, and the online systems are really good. Don’t overlook the online backup, I think it is an essential part of most backup strategies.
And remember, your back up is useless if it gets stolen or burned with your computer!
Perkinsy: What steps did you take to satisfy yourself it won’t happen again?
Hubble: There are certain things you can do to ensure your machine (I am talking Windows here) is in good working order and your hard disk drive is in good health. The first is to run a program called chkdsk on the machine. This will require a reboot. Here is where you will find instructions: http://support.microsoft.com/kb/315265. The second thing you can do is to do run disk defragmentation every now and then. Disk drives will start to get fragmented after while – the computer tries to write to a location and finds it is not quite big enough, so the computer splits the file into multiple separate fragments. This can slow things down and increase the risk. Sometimes a single large file can be split into more than a thousand fragments! Microsoft instructions for defragmenting can be found here: http://support.microsoft.com/kb/314848.
Perkinsy: Can you recommend one or two websites that use non-technical language to explain more about backup systems for home computers?
Hubble: These might help:
Perkinsy: Thankyou very much for explaining all this!
You can read more about Hubble’s thoughts on cloud computing by following his blog at www.cloud81.wordpress.com
We lost a lot of time over the weekend because of this but fortunately all my work was successfully retrieved except for one hour’s work on Saturday. There are some horror stories out there about computer disasters. Fortunately ours was not one of them. What computer disasters have you faced?