[Cialug] Landscape of SQL servers

[Matt]

There is a very loud (likely majority) in the IT world that will 
constantly repeat to you "RAID is *NOT* a BACKUP."  I've heard it many 
times in LUG meetings.  A backup's purpose is to allow you to recover 
not only from failed equipment (from which RAID does an excellent job of 
protecting you... assuming you pay attention to all your arrays and make 
sure to notice and replace failed drives quickly) but also from computer 
errors (program, virus, OS bugs that can cause data corruption) and 
human errors (oops, I just typed `rm -rf /` because my buddy told me it 
would optimize my intertubes and help connect them to my megapipes!).

In a perfect world, backups should also protect your data from acts of 
God and evil men, plus stuff like faulty wiring and plumbing (your house 
gets struck by lightning, which causes the gasoline, detcord, and C4 
that your mad scientist neighbor has been stashing in your storage shed 
while you and your family are off on vacation to explode, which causes 
the house to shake so violently that the plumbing for the 2nd story 
bathroom bursts and pours water on your 1st story office computer and 
your 21U rack in the basement).  A good backup system keeps a copy of 
all important data not only nearby for a quick restore when a tiny 
disaster strikes, but also keeps that same data somewhere safely offsite 
in case a major disaster has a much wider area of effect.

All that said, I am a huge fan of RAID.  I had a faulty PSU in my 
desktop machine that was eating a hard drive every couple of months.  It 
took me a while to figure it out, but I never had to reload from backup 
because I was able to replace the failed drive before the next drive 
would die.  What RAID was designed to do was to not only protect your 
data, but to keep that data accessible, even when a failure happens.  It 
will keep you working when a drive fails, and it will give you time to 
replace it, so it can help you avoid one of the major hassles of a 
backup system: recovering from a loss.  It can also make sure that your 
primary system and your primary backup are safer places to store your 
data.  It just can't mitigate human error, data corruption, or natural 
disasters.

-- Matt Stanton


On 10/14/2016 9:14 PM, L. V. Lammert wrote:
> On Fri, 14 Oct 2016, Scott Yates wrote:
>
>> Sorry, but I still think you are wrong.  This article states many of the
>> reasons I think so:
>>
>> https://www.mongodb.com/blog/post/backup-vs-replication-why-do-you-need-both
>>
> Two problems there - it is specific to the configuration of a specific
> database (MongoDB), that only describes the tools available in that
> enviornment.
>
> Second problem, it only describes threat solutions for that enviornment.
>
> I guess we're both entitled to our opinions.
>
> 	Lee
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