Backups
This is one of those topics that separates the men from the boys, so to speak. Backups. Always, always, always have them.
Do not treat RAID arrays as if they are inviolable. It’s always a possibility that more than one disk could fail. And it’s also a possibility that the hardware itself could fail, thus corrupting the array. RAID is more fault tolerant than one disk, but only just. Don’t depend on it. A high-traffic company learned this a few weeks ago, taking no backups and depending on RAID mirroring. I’d be surprised if the sysadmin who worked there ever works again. Not doing at least some kind of backup is stupid, and possibly even negligent.
It doesn’t really matter on what medium you do the backups onto. If you have a small amount of critical data, you might consider putting it on CDs or DVDs and sending it offsite. If you have a lot of servers, you might want to consider tape. For my personal systems, I just copy it off onto hard drives that aren’t physically onsite. Restoring through a DSL connection is a pain, but it beats losing everything.
There are several ways of doing backups, and the good news is for Linux systems all of the software you need comes with your system. You can use scp (which is good for brute force backups). You can use rsync (which will keep your backups up to date, good for having a recent copy, not good for having archival copies you can go back to). mkisofs and cdrecord are good tools to create your backups to send to DVD. There are also enterprisey systems like Amanda. There are lots of different ways to do it and I won’t go into them here, but you can feel free to put your favorite method in the comments if you think it will help.
The main thing that I want to get across in this particular article is – do it! It doesn’t take much time to set it up, and you’re not going to think much about it until things die – at which point it will (maybe even literally, depending on whose data you’re storing) save your life.
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