[mythtv-users] Linux software raid question

Jan Ceuleers jan.ceuleers at computer.org
Thu Jun 5 18:31:49 UTC 2008


David Brodbeck wrote:
> With any RAID system your main recovery strategy should be a good
> backup.  RAID is mainly about protecting your uptime, not your data.  It
> will keep your system going if a drive dies, but if you get a corrupt
> filesystem or delete the wrong file the RAID array will faithfully
> duplicate the problem across all of the drives...

You're absolutely right.

One data point: my main server has six disks. I've set up a RAID5 array 
across four 320GB drives, and that is my main storage. I've also got one 
500GB drive that I use for weekly backups (using dirvish). The other 
drive is a 320GB hot stand-by for the RAID set.

The backup drive and the stand-by drive are normally spun down, so they 
don't add much to my carbon footprint. I also bought these two drives 
some months after the first four drives, in order to reduce the 
likelihood that they might fail at around the same time as the RAIDed 

I've carefully split my data and system files into to-be-backed-up and 
not-to-be-backed-up. For example, the root filesystem of my diskless 
front/backend also sits on the RAID5 array, but I don't back it up. 
That's why the 500GB drive is ample for weekly backups going back 3 
months (also because dirvish/rsync's hard linking capabilities cut down 
on the amount of space needed).

Cheers, Jan

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