

EC2 High Memory Cluster Eight Extra Large Instance (244 GiB RAM) - jeffbarr
http://aws.typepad.com/aws/2013/01/ec2-for-in-memory-computing-the-high-memory-cluster-eight-extra-large.html

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michaelt
Almost all the big EC2 outages have been due to EBS, and you have to pay extra
for it as well. Netflix steers clear of it [1].

Does anyone know why Cluster Compute and Cluster GPU Instances [2] (including
this new one) make using EBS mandatory?

[1] [http://techblog.netflix.com/2011/04/lessons-netflix-
learned-...](http://techblog.netflix.com/2011/04/lessons-netflix-learned-from-
aws-outage.html) [2]
[http://aws.amazon.com/ec2/faqs/#Does_use_of_Cluster_Compute_...](http://aws.amazon.com/ec2/faqs/#Does_use_of_Cluster_Compute_Instances_differ_from_other_Amazon_EC2_instance_types)

~~~
crb
Two reasons come to mind:

* the failure rate of an EBS volume (assuming a bug-free EBS software stack!) _should_ be less than any one spinning disk

* these machines don't have disk space set aside for copying the root volumes to them from S3 to boot. (There's a 10GB limit, and to allow for this to be somewhere, you'd have to have another SSD, or partition the existing ones.)

There's a good blog post about it on Rightscale:
[http://blog.rightscale.com/2012/11/02/new-ec2-instance-
types...](http://blog.rightscale.com/2012/11/02/new-ec2-instance-types-and-
coordinated-failures-in-the-cloud/)

esh's "You Should Use EBS Boot Instances" also lays out a number of good
reasons to use EBS for boot: <http://alestic.com/2012/01/ec2-ebs-boot-
recommended>

You at least have two 120GB ephemeral SSDs to play with when you're running -
a luxury you don't have on the new M3 classes.

~~~
Dylan16807
It's not really the rate that's the issue here, it's correlation between
failures. The chance of losing a third or more of your machines at once is
enormously higher with EBS.

Partitioning a disk should take seconds; I don't see why it would be an
impediment. As it is, someone can do it themselves but now it'll be a custom
job and less reliable.

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mariuz
One way to scale Firebird Database is to put it on memory virtual disk or
ramfs

On linux i can mount a partition in memory (Install ubuntu/debian)

sudo mkdir /mnt/ram sudo mount -t ramfs -o size=200G ramfs /mnt/ram mount to
show you the partitions mounted

and then move your database into the ram partition

cp -rp /var/lib/firebird/2.5/data /mnt/ram

That large instance could help you with the Firebird cache settings also the
extra SSD could do wonders

Inspired by the stack overflow big fat server architecture

[http://highscalability.com/blog/2009/8/5/stack-overflow-
arch...](http://highscalability.com/blog/2009/8/5/stack-overflow-
architecture.html)

~~~
jacques_chester
Well, two things with that. Three really.

First, does AWS allow ramdisks? It's been a few years since I tried to mount a
ram disk on Xen, but it was not possible at the time.

Second, most databases are smart enough to shuffle stuff into RAM for you,
starting with indexes and commonly-accessed tables.

Third, the "D" in ACID stands for "Durable". If you want an in-memory store,
use an in-memory store. RDBMSes do sorta kinda rely on the assumption that
stuff written to disk is _actually written to a disk_.

~~~
mariuz
Yes it AWS allows ramdisks , here is the output from a machine

root@ip-amazon-ip:/home/ubuntu# mkdir /mnt/ram mount -t ramfs -o size=2G ramfs
/mnt/ram mount ramfs on /mnt/ram type ramfs (rw,size=2G)

There are the cache and memory settings Fore Firebird but is better to put the
main full database on the fastest storage and that is RAM for the moment

In Firebird we have a nifty feature called Shadow that creates a life
snapshots of the active database (Think of it as Replication in real time) so
you can activate it and keep a safe database on the SSD/HDD

<http://ibexpert.net/ibe/index.php?n=Doc.DatabaseShadow>

------
politician
Recently, antirez pointed out that redis was essentially memtest86;
consequently, he has had to spend a lot of time chasing down phantom bugs due
to memory modules with stuck/flipped bits. At that time, I think HN was left
wondering whether Amazon uses ECC memory in its EC2 machines. Do we know
whether that's the case now?

~~~
wmf
All Xeons and Opterons (in other words, all EC2) use ECC.

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profquail
Colin Percival (cperciva) already has FreeBSD 9.1-RELEASE running on these!

<http://pastebin.com/SCMUJNDt>

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pieter
This instance was announced at RE:invent 2 months ago, and is now available.
You can try one out for $0.34 / hour with spot instances.

~~~
tiernano
It does not seem to be possible to launch a spot instance of one of these...
the web interface wont allow it, anyway... Still, about $3 per hour to play
with a machine of that size should be interesting...

~~~
res0nat0r
You might have to use the ec2-api-tools cli package to launch spot requests
for this instance type right now. The AWS Console doesn't always seem to be
updated at exactly the same time as new instance releases.

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zippie
RAM isn't a cure all for big data applications and presents its own set of
challenges. The largest issue is with traversal and data access latencies
simply because of the virtual memory management overhead that is required.

I've run into this problem with our btree search indexes on bare metal
(~96GB), some more reading:

<https://github.com/johnj/llds>

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StefanKarpinski
Some time ago (mid 2011), I was trying to use an AWS 64 GB machine for some
largish work and discovered that I couldn't actually allocate anywhere near
all of the 64 GB of RAM I was supposed to have access to. As I recall, writing
a simple C program to do binary search to pinpoint exactly what the max amount
of memory I could malloc was, it failed somewhere around 34 GB – so just over
half of the memory I was supposed to have access to. Makes me wonder how much
of this 244 GiB you can actually use when you spin up one of these machines.

------
jahewson
I'd like to see a machine with an SSD from Amazon that wasn't so big and
expensive.

~~~
devopstom
I don't think that's possible. Big|Fast|Cheap, Choose two. (or one, under some
circumstances).

~~~
Dylan16807
I think you misread the parent. jahewson asked for a machine that is Fast and
Cheap and Not Big.

More specifically they want to upgrade a weaker machine with an SSD instead of
getting a high end machine with an SSD.

