[mythtv-users] Should I use LVM on this new raid?

[David Brodbeck]

On Sep 23, 2007, at 6:23 PM, Jay R. Ashworth wrote:

> On Sun, Sep 23, 2007 at 07:43:15PM -0500, Craig Huff wrote:
>>    Even *this* believer in tape backup might be tempted to "just add
>>    more disks and mirror it".
>
> 1) If it's a mirror, rm -rf /video will still erase it.
>
> 2) If you can't take it out of the building, it's not a backup.
>
> http://philip.greenspun.com/wtr/illustra-tips.html
>
> and search down for "studs".  It's quite interesting.

One alternative to the "break the mirror and then back up the  
disconnected drives" method is to use a filesystem that supports  
snapshots.  XFS does, for example.  You can freeze a snapshot and  
then back up the snapshot.  This requires enough spare disk space to  
contain all the filesystem changes that occur between the time you  
create the snapshot and when you delete it, however.

This is handy for databases because creating a snapshot is a very  
quick operation, so you don't have to keep the tables locked for long.