[svlug] new disk is installed - raid

[Alvin Oga]

hi ya rick

> Rick Moen wrote:
> 
> 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.

i'm trying to avoid converting a single disk into raid1 after the fact
since it'd probably be just as fest to do it right ( less steps )
by a simple reinstall directly into raid1 

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

or raid1 is never to be used as "backup" ...
not even considered for "substitute" .. "never" trumps substitute ?

> 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.

it works as described if and when,
people have raid properly configured and tested prior to initial deployment
	- "properly tested" is where most folks fail

> And, by the way, I'll believe in SVLUG having reliable 4-hour backups
> when I see it.

vi /etc/aliases

	svlug:	svlug at backup.svlug.org

	--->> all incoming emails is backed up within seconds
	though is a whacky way ... it doesn't lose any emails during
	the 4-hr time period of no backups
 
>  You don't want to know about the group's backup
> practices, trust me.  It'll frighten you.

if you mean there is no backup ... its not that frightening in that
lots of people do not have backups ... thus the calls for "help"
after the fact .. and there's nothing we can do except rebuilding
files from inodes on 500GB disks, assuming the platters are intact

> > 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.

nah .. worst case ... i've seen people do is reinstall from scratch
because the single disk replacement thingie didn't work so they lost
it ( on both disks ) and whatever else that was not backed up
	- in which case, why bother with raid if it doesnt work

	- hiring somebody to come and config/setup/test raid costs too much 
	and paying to watch the resync'ing 1TB of raid data is too much to watch

c ya
alvin