11 2005 Clustering Ltsp

8/8/2019 11 2005 Clustering Ltsp

1/16

Clustering LTSP

Ivan KrstiHarvard University

Cambridge, MA, [email protected]

November 5, 2005

LTSP by the Seaway

part of Ubuntu Below Zero

Montreal, Canada


2/16

Who am I? software architect, journalist

specialize in architecture and security of large-scale web applications

currently on leave from Harvard University,working as Director of Research at the MedicalInformatics Laboratory at Zagreb Children's

Hospital run a hospital-wide, clustered LTSP

deployment


3/16

Clustering

30-second primer, two acronyms:

HPC high performance computing

HA high availability

What do we want for clustering LTSP?

definitely HA quite possibly some bits of HPC


4/16

Why cluster LTSP at all?

Because you should be scaling out, not up

... so any setup that makes it hard to scale

out should scare you! There is nothing intrinsically unscalable

about LTSP

Scaling out to two machines is alreadypossible with ISC dhcp3-server magic

But that's it. Can't use the same strategy to

scale past two machines.


5/16

Don't get too excited

The first thing people get happy aboutwhen I talk about clustering LTSP

If an LTSP server dies, my users'

sessions will get transparently

moved to another server, and the

users won't notice! Woohoo!

Can that be done?


6/16

Uh...

NO.


7/16

So what's it good for?

Even if your sessions aren't migratingtransparently, you can still use LTSP

clustering to ensure 100% availability Even if a server fails and a session dies, the

users can reboot the client and log in againimmediately!

On top of this, you get essentially linearscalability

Which works beautifully.


8/16

What's beautiful scalability?

Order a server without any disks

Throw it in your rack

Turn it on

... profit!

Configuration is magically handled foryou, and you can now support manymore clients.


9/16

What was that about HPC?

It turns out that not all users are equal

And neither are applications.

One user might be running a Javaapplication that constantly sucks 60% of

the server's CPU

Other users might generally run resource-unintensive tasks that sometimes get CPU-

hungry, but you can't tell ahead of time


10/16

If you do connection balancing

These scenarios are a nightmare

Fifty users

fair split 24 very unhappy users

But you can't predict how much resources a

user will need before he logs in! Macromedia Flash

Java


11/16

The kernel knows more than you

So let it worry about resourcemanagement!

Introducing OpenSSI HP project, now largely community-maintained

Stable release for 2.4 kernel, development

release on 2.6 Integrates best of both worlds: HA and HPC in

one convenient, powerful package

http://www.openssi.org


12/16

OpenSSI

initnode concept, with failover

usually diskless cluster nodes

CFS magic single transparent cluster-wide IPC space

process migration!

load leveling!

Bingo!


13/16

How does this help us?

Set potentially demanding applications tobe load leveled!

Fifty users? No problem.

OpenSSI won't break a sweat.

Scales? Very, very well, and it'll be even better in the

future.


14/16

But I'm not a clustering guy...

No problem

Ubuntu integration forthcoming!

Likely unofficial OpenSSI support in Ubuntu6.04 (Dapper)

Working on official OpenSSI support in

Dapper+1, out in October 2006 Can play with it pretty easily now on

Debian, if you can spare two machines


15/16

Boldly going where no thin client

has gone before Future: instant gratification?

Plop in an Edubuntu CD

Choose to perform a clustered LTSP

installation

Voila: you get an Edubuntu environment

with pre-installed LTSP and clustering,

and an easy administration GUI!


16/16

Conclusion

Clustering LTSP lets us...

scale out as much as we like, and trivially

make optimal use of server resources bymeans of automatic load balancing

essentially guarantee 100% availability for our

deployment

watch a whole new dimension of clueless

questions on #ltsp!

Questions?

11 2005 Clustering Ltsp

Documents

Transcript of 11 2005 Clustering Ltsp