[erlang-questions] Using Key/Value store with shared storage

[Max Lapshin]

No.

SANs and other "enterprise" hardware are designed for cases, when vertical
scaling is cheaper than horizontal scaling.
This cases usually include fixed and predictionable growth of data flows,
for example calculating salary or something else.
Usually it happens when you cannot control software, for example you need
to install Oracle with SAP and it is easier to buy
most expensive raid array than to get into SAP sources and ask it to shard
(hehe).


It is very, very hard to scale such "enterprise" installation 10 times,
because scaling price for such devices is not linear.
This is why people make "webscale" software, that avoids all that costy
hardware. What for to buy RAID controller if
you can just copy data to another server and another datacenter? Yes, this
HDD will break, but our data is copied to another location.

If you stick to SAN device, you loose ability to scale 10 times on slashdot
effect during one day, but using 20 slow amazon nodes can give you such
possibility. You cannot just go and buy another SAN in wallmart or make
your existing device 2 times faster.


But of course, expensive SAN is a very nice toy to play if customer is
going to pay for it =))
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