
Why MongoDB thinks single server durability is overvalued - rgeorge28
http://blog.mongodb.org/post/381927266/what-about-durability
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seiji
Tokyo Cabinet Dude™ mentioned the same thing a few months ago:
<http://1978th.net/tech-en/promenade.cgi?id=6>

Summarized: "Please use replication because hardware breaks down."

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pibefision
What sites are using MongoDB on production?

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dmytton
We're using it for <http://www.serverdensity.com> where our database is around
600GB replicated over multiple data centres.

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uggedal
How do you handle security when replicating across data centers? It's my
understanding that MongoDB supports authentication, but not encryption.

~~~
cmallen
An encrypted tunnel that isn't initiated at the database level should work
fine.

Addendum: I'm more than a little puzzled that someone would be aware that a
particular nosql database didn't support encryption natively and yet wasn't
aware how tunneling works.

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z8000
You are making an assumption in your addendum that uggedal does not understand
how tunneling works. All he did was ask how they handle security not "how does
tunneling work?"

~~~
uggedal
I've actually used <http://www.tinc-vpn.org/> to tunnel Tokyo Tyrant between
data centers. It was a bit flaky at times though, so hardware Cisco tunneling
looks like a good option if you have access to the firewall in your
environment (eliminates all cloud providers).

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moe
I love how he mentions "water damage" in the list of things that can happen to
a server. That made me snicker... who doesn't hate those leaky datacenter
roofs!

~~~
jerf
At work, a server that I am responsible for the software on, but not the
general IT-type management, was becoming increasingly flaky. It kept powering
down at odd times, once managing to corrupt a MySQL database pretty badly.
Shortly after a firmware update, it ceased coming up. I honestly did assume it
was something in my software update, as updating this server was often the
next step after QAing the software. Once I realized that I couldn't even ping
the device (which I am 2000 miles from), I had to send in the local IT
personnel to log in physically.

This is when they discovered that the device would no longer physically turn
on. Next step is to de-rack the device, at which point some strange
discoloration was discovered in the holes in the case. Next step was to open
the case, where it was discovered that _the entire machine was full of mold_.
The roof was leaking, and this was on the top of the rack directly under the
leak. In Silicon Valley, leaky roofs can apparently take a while to discover,
but they will eventually make their presence known.

Now, this was in a local office, albeit a relatively well-equipped on that
holds in the hundreds of rack machines, not a colo. But you know what? Shit
happens. And you don't _really_ have a guarantee that shit won't happen just
because someone has magically slapped the word "data center" on a building.

~~~
z8000
_once managing to corrupt a MySQL database pretty badly._

Rare as a Himalayan Snowcock spotting!

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z8000
I have some concerns about MongoDB and since it gets such good reviews from a
lot of people, I think I am either making a big deal out of nothing or
everyone else is crazy.

I wrote up some comments elsewhere but this thread is more populated with
people _using_ mongo in production.

Elsewhere = <http://news.ycombinator.com/item?id=1110366>

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CaptainZapp
"First, there are many scenarios in which that server loses all its data no
matter what. If there is water damage, fire, some hardware problems, etc..."

Err! So there are burglers and other evildoers sneaking through the city. Does
that mean I should stop locking my door, since burglaries happen anyway?

"In the real world, traditional durability often isn’t even done correctly. If
you are using a DBMS that uses a transaction log for durability, you either
have to turn off hardware buffering or have a battery backed RAID controller."

Or you write to raw devices, which perform pretty neatly. The fact that a
_lot_ of databases are set up and managed in a crappy way justifies that this
is considered the norm? I don't think so.

Here's for the disclaimer. I don't know anything about MongoDb and not a
helluvalot about NoSQL databases.

But I think the reasoning behind this post is not very sound. No matter which
database.

