Sunday 2 August 2015


We all know about data backups, and we all have them. Don't we? Well, if you don't, then you haven't been listening.

But what about non-data backups?

The power supply for my firewall failed. Last time, I did a power cycle and it worked again, but after this second failure, it's no longer to be trusted. Fortunately (actually, no luck was involved) I bought a replacement PSU for it on Ebay several weeks ago, after it failed the first time. So I've put that in place. But that leaves me without a backup. Well, not quite, I have a backup firewall and a backup power supply. So even if both the firewall and the PSU go down, it'll take me a few minutes to replace it.

But for something as mission-critical as the firewall (no firewall means no network), I want a second backup, because wouldn't it be horrible if the unit failed and then the backup didn't work? Because you probably don't check if your backup works every month. I know I don't.

So I have a second backup firewall ... but no PSU for it.

Last time I looked into this, I decided that I could make a PSU for a Cisco 506e firewall out of an ordinary PC power supply and the cable from a dead Cisco 506e PSU, by soldering the wires from the Cisco cable to the relevant wires on a socket for a PC PSU. So I did the necessary soldering, but didn't test it, because I have so much confidence in my ability to work out which wires to connect to which and in my ability to solder. Not.

Today, I tried it out. First, I connected that cable to a PC PSU, and powered it on, and checked that the voltages on the Cisco cable were right. Then I connected it to one of my backup Cisco 506es, and it worked! So now I have my secondary backup.

So what I'm telling you, is, just like you make a backup for your data in case something bad happens, so you should also think about your hardware, and think about what things you should have an on-site backup in case something goes wrong, and getting a replacement might take a few days, during which you're out of action.

Because things do go wrong. Unexpectedly.

1 comment:

  1. Whilst I usually find the techie blogs interesting, I can't recall ever having read what all of the servers are actually running. Perhaps addressing this gap would put them all into context?