[svlug] new disk is installed - raid

[Rick Moen]

Quoting Scott Hess (scott at doubleu.com):

> I've been there, you can instead build a degraded RAID1 on the new
> drive, copy everything over, reboot from it, and add the old drive to
> the RAID1 volume.  Works swell...

That would work.

> In fact, after running for years with RAID1 on my primary machine, I
> switched to using a pretty minimal dedicated backup server running
> rsnapshot.  RAID1 is a good solution if you need strong uptime
> guarantees, not so helpful if what you're looking for is a good
> _backup_.

RAID1 is not -- not _ever_ -- a substitute for backup.

The purpose of RAID1 is to have continuous operation when (not if)
the hard drive fails, so as to avoid having to build a new OS load,
restore from backup, and lose all machine state (including mail) since
that backup.  And have downtime until that is done, tested, and
redeployed.

And, by the way, I'll believe in SVLUG having reliable 4-hour backups
when I see it.  You don't want to know about the group's backup
practices, trust me.  It'll frighten you.

> And I'm right with you on the increased admin overhead of RAID1.

The worst that can happen with a RAID1 "md" pair is that you don't use
that capability, in which case all you lose is the purchase price of a
second hard drive.  Which in this case I'm offering.