[lug] Backup

[Jeffrey Siegal]

On Dec 20, 2005, at 13:43 , Siegfried Heintze wrote:

> I would like to see of discussion of RAID for home office systems.  
> After
> discussing my home office software consulting needs with some local
> retailers, they talked me out of RAID because RAID only protects  
> against
> hardware failures and not hackers.

True and as others have pointed out, it also doesn't protect against  
human error, filesystem corruption, etc.

BUT.... protection against hardware failure is can be pretty  
worthwhile.  For the cost of an extra drive, I'd much rather swap out  
a drive when one fails rather than have to go through a restore  
process.  Plus it means your system won't necessarily fail just  
because a drive fails, so there can be advantage in terms of reducing  
downtime, particularly unplanned downtime.

My experience is that drives are just a lot less reliable now too.   
Call it a race to the bottom in terms of quality, or tradeoffs in  
favor of capacity/cost or who knows what.  But after 10-15 years  
without a drive failure (across multiple systems), I've had several  
in the past few years.

> (1) So if you are using RAID 1, can I infer that you believe the  
> threat of
> hardware failure is greater than that of hackers or viruses or other
> destructive software (like accidentally typing fdisk)?

No, you should infer that the threat of hardware failure is high  
enough for the benefits of RAID mirroring to justify the cost,  
independent of those other issues (which also need to be addressed).

> (2) I was told it is not effective to have half a RAID1 set powered  
> down 99%
> of the time (which is what I wanted to do so no hacker could access my
> backup). Is this true?

Well, when its down its not giving you much protection that's true.   
If you understand the tradeoffs this still might be a reasonable  
configuration though.

> (3) In addition I hope to install Mondo rescue make a bootable  
> image of my
> boot disk on DVD and then I could store this off site should my  
> house burn
> down. I heard, however, that DVDs are less than ideal if they are  
> more than
> a year old. Is this true?

Actual and perceived media reliability is all over the map.  Frankly  
if I had an application where it mattered I would not rely on any  
"conventional wisdom" or even vendor promises and I would design some  
sort of periodic validation into the process.