Bob Goodwin writes:
I had a mainboard fail in a box I use as a server, I moved the hard drive into old computer and carried on from there. Now I've replaced the board and intended to set it up using Raid to mirror two drives. However I have been wondering if it wouldn't work just as well to periodically rsync the drive in use with a second drive?
That seems a more direct approach and I could easily check to make certain that the second drive was a usable copy, insurance against loss of data.
Am I going wrong somewhere in my thinking?
Raid, and rsyncing, are not equivalent to each other. They solve different problems.
For starters, in your case taking an existing partition and turning it into a RAID volume is going to be a big project. You'll have to back up your existing data somewhere, erase the existing partition, create a raid partition, then restore your data from backups. I'm not aware of a way to turn an existing non-RAID partition into a RAID one.
rsync is easier to set up when you have existing data, and I do have a few laptops where I have a daily job to rsync their data onto a different server.
On the other hand, RAID is generally faster, and runs in realtime. With rsync, you do have some window of vulnerability where you will lose everything since your last rsync run, when you have a failure, where RAID provides up to the second redundancy.