For this post I would like to cover what are probably some fairly obvious concepts for experienced board owners. The first question that needs to be asked is: What do I need to include in my backup strategy?

Code and Data

There are two components of your board: code and data. If you need to move or restore your board you need both parts; one is useless without the other. I will submit that data is more important than code. If you have code with no data, you’ve lost what makes your board unique. If you have data with no code, you can at least download a free set of code for phpbb and use it. But the question remains… what should I include in my backups? The answer is, of course, both.

Backing Up Source Code

There are some folks that run very sophisticated code management systems. They might include SVN (an open source code management system, link at end of post) or something similar. I don’t do that. Sometimes I wish I did but I have never needed anything that complex because I am the only developer on the system. I don’t have to deal with supporting more than one developer. I could use a system like SVN for tracking code changes, but so far I have not needed anything that sophisticated.

But I do back up my code. It’s not done on a scheduled basis, because code changes only happen when I make them. I started off on a tangent about my development process and decided to move all of that information to a new blog post rather than here, so for now let me just assume that there are code changes that happen. Before I put new code onto my production web server I will make a copy of the existing code and keep it easily available on the server. If some sort of bug managed to slip through my testing, I need to be able to fix it immediately, or if I cannot, I have to copy the old code back so that the board doesn’t go down. Once the the board has been updated and verified then the copy of the code will be downloaded off of the server and archived on my home network. I include a “readme” file that details the changes made and store it with the copy of the code.

I then will also make a copy of the current production code, and that is also downloaded to my home network. In the event of a hardware failure I would restore my code backup to a new server and follow that with my most recent database backup and my site is up and running. Which brings me to the next concept…

Backing Up Your Database

Code is not supposed to change unless you know about it. Database content can literally change every second. For that reason it is much more important to make regular database backups as compared to your code backup process. How often do you back up your database? There is a simple answer to that… how much data are you willing to lose?

I used to run my database backup process on Saturdays. That worked fine until I messed up the database on Thursday afternoon. By going to my backup file I lost everything that happened from Sunday through Thursday afternoon, or over 100 hours of board activity. With the level of activity I had at the time, that was about 50 new users.

I now run my backup process every night, so the maximum data loss would be one day rather than 4+ days that I had lost before. Of course my board is a lot more active today than it was years ago. An average twenty four hours of activity on my board today is:

• 31 new users
• 387 new posts
• 77 new topics

Are daily backups enough, given this information? For now, yes. At some point I may shift to capturing the data every six hours (four times a day) to cut down my potential losses, but for now I am comfortable with these numbers.

Next Post: Database Backup Scripts

In the next post I plan to go into more detail about how I manage the automatic database backups. It’s fairly simple (which is good) and automatic (which is even better).

Related Links

• Subversion Code Management

I lease a dedicated server from a hosting company so I have root access. I do several layers of backups, including an automatic download to a secondary server located in my home office… and storage on a RAID (mirror) device. This all runs during the wee hours of the morning. But what if you don’t have the same choices as me… does that mean you can’t have the same advantages?

The other day I noticed an ad being displayed on the bottom of one of my boards via the Google Adsense program. I can’t click on the ad (it’s a violation of Google’s Terms of Service to do so) but they provide a tool that lets me determine what the target URL is. It was for a service called Zmanda Open Source Backup. The “open source” part caught my eye, so I went to their site. In a nutshell, they provide a backup program. That, in and of itself, probably isn’t that interesting. But what is interesting is that one of their target devices can be Amazon.com’s S3 service. Amazon.com offers a data center service where you pay for the space that you use. It’s fully redundant / fault tolerant and comes with a 99.9% uptime guarantee. I would rather see five 9’s instead of three, but that’s not bad.

As a brief aside, for those who are not familiar with the term “five 9’s” as I have used it here. The phrase “five 9’s” refers to 99.999% uptime. To put that into perspective, three 9’s implies up to nearly 9 hours of downtime in the course of a year. Five 9’s implies only about six minutes of downtime during an entire year. Big difference? Only if you need your data at some point during those nine hours.

When I reviewed their service description I saw that instead of selecting a tape or disk device as the destination for my backup, I would be able to select the Amazon S3 data center. My own backup process includes keeping a rolling archive of files for each database on my server, including clients that I host. The most recent backup file is kept on the server itself, on a secondary hard disk. I keep generations of backup files on my home network going back quite a while.

With Zmanda’s backup system it seems that I could do the same thing with the advantage that I could run a restore from anywhere with Internet access. Today if I need to restore I have to be at home.

There is a cost, of course. The S3 service from Amazon has a charge associated with it. But I paid over $1,000 for the RAID device that I currently use for my backup destination. I also have to maintain a linux box that runs the cron jobs required to download the files after they appear on my production server. I haven’t investigated the cost of the S3 service but I bet it would be cheaper than that.

For now I’ve already made the investment, so I will continue to use my existing process.

Coming Attractions
I have a few other posts related to making board backups coming out over the next few months (as I get time to complete them). I wanted to start with this one because I thought it was an interesting service. In my next post I plan to detail why backups are important, and how to go about determining a backup strategy that works for your board.