[Swift-devel] swift-on-ec2
Ian Foster
foster at mcs.anl.gov
Wed May 16 15:19:18 CDT 2007
Kate:
I want to emphasize that I was *not* dismissing the issues below as
distractions.
What I meant was: given that you are working on developing a "virtual
cluster", which I am pretty sure will be able to execute Swift apps,
let's focus on getting that done, rather than worrying about "special
casing" it for Falkon, adding dynamic node acquisition, or the other
things that people started discussing as potential extensions.
I understand from our IM conversation today that the "virtual cluster"
is ready for us in a "static environment" such as some machines in our
lab. In a "dynamic environment" such as EC2, it is not quite ready for
use yet. Thus, you won't be able to get Swift running on EC2 tomorrow.
Ian.
Kate Keahey wrote:
> Ian,
>
> you seem to be referring to the necessary /etc/hosts configuration as
> well as workers registering with the torque headnode below as
> "distractions" -- I agree they can be very distracting, but in my
> experience without these distractions a cluster (virtual or physical)
> won't work in the way such clusters are typically expected to work.
>
> What I said in my mail is that we can set up a base cluster locally so
> that somebody like Ioan can finish the configuration (i.e., install
> Falkon on it). We will configure this cluster once and leave it
> deployed as long as needed.
>
> Once we have the front-end to EC2 working (which we don't have yet
> although we are close) we will deploy this cluster on EC2 and provide
> methods that will automate this last little bit of configuration that
> *always* has to be done on deployment.
>
> I also think it is quite important that we spend the time tomorrow
> discussing what exactly we are trying to do -- right now, it looks to
> me like it might make more sense to not use clusters (it will help
> with the "distractions" if we don't).
>
> I realize that you are eager for us to get things to run -- I am eager
> too, but I honestly think we will get there faster if we plan better.
>
> Ian Foster wrote:
>> Kate:
>>
>> I personally will be delighted if you could run the virtual cluster
>> on ec2 tomorrow. I know that there are lots of ways that you could
>> refine its config, local expts that could be performed, etc., but
>> perhaps we could try bypassing those things, which seem somewhat like
>> distractions to me?
>>
>> Ian
>>
>>
>> Sent via BlackBerry from T-Mobile
>> -----Original Message-----
>> From: Kate Keahey <keahey at mcs.anl.gov>
>> Date: Wed, 16 May 2007 09:24:02 To:itf at mcs.anl.gov
>> Cc:swift-devel-bounces at ci.uchicago.edu, Ioan Raicu
>> <iraicu at cs.uchicago.edu>, swift-devel at ci.uchicago.edu, Borja
>> Sotomayor <borja at borjanet.com>
>> Subject: Re: [Swift-devel] swift-on-ec2
>>
>>
>>
>> Ian Foster wrote:
>>> Kate:
>>>
>>> If we configure the virtual cluster with a full LRM, as you propose
>>> (and it seems have already done--great work!), then we can use this
>>> to start Falkon executors--as we do today on regular clusters. So it
>>> seems to me that we have all we need. How about you and Ioan spend
>>> your time on Thursday running something on EC2, to make sure it sorks?
>>
>> As I suggest below, I think it would be easiest if we could deploy
>> and debug a small static cluster locally first, and we can probably
>> give it a shot tomorrow. We still don't have access to the Xen nodes
>> on TeraPort (although hopefully that might change by tomorrow) but I
>> asked Rick to rebuild a couple of nodes at ANL and he did, I think
>> for a test that should give us enough resources to play with.
>>
>> At the same time -- if there are multiple ways of doing this, and
>> perhaps better ways than simply using a virtual cluster, we should
>> discuss them now. It is not completely clear to me what the
>> relationship between Falkon and Swift is, and what the specific
>> objectives are (other than that dynamically provisioning resources is
>> required). It looks at this point like the objectives probably
>> overlap with what Ioan, Borja and I wanted to talk about (which I
>> thought was a separate project, but am thrilled to find out is
>> related) so how about we come up with a design tomorrow and post the
>> notes on this list (is this a good venue for that?) and then others
>> can shoot them down.
>>
>>> Regarding choice of LRM: have you looked at SGE? That is what quite
>>> a few others seem to be using.
>>
>> Yes, we have. We also collaborate with others who do, as well as with
>> Sun... As you may remember, Borja did the scheduling work for his
>> thesis in the context of SGE. Last time we talked though, Torque was
>> the scheduler of choice for the virtual cluster LRM so we used that.
>>
>> The usage of SGE you are referring to above -- is this in the context
>> of virtualization projects, or as LRM for various Falkon-related
>> applications?
>>
>>> Ian
>>>
>>>
>>>
>>> Sent via BlackBerry from T-Mobile
>>> -----Original Message-----
>>> From: Kate Keahey <keahey at mcs.anl.gov>
>>> Date: Tue, 15 May 2007 23:28:07 To:iraicu at cs.uchicago.edu
>>> Cc:swift-devel at ci.uchicago.edu
>>> Subject: Re: [Swift-devel] swift-on-ec2
>>>
>>> First -- this is a very useful discussion, would it be possible to
>>> see all of it. We need to understand the requirements and trade-offs
>>> in some detail to figure out the best way to make this work. I see a
>>> few different interaction threads somewhat mixed up here though so
>>> just to make sure we are all on the same wavelength, here is some
>>> context.
>>>
>>> Ian and I have been talking on and off about providing a workspace
>>> service implementation with EC2 backend. The benefit for that would
>>> be that users could deploy the same VMs using the same interface to
>>> either TeraPort or EC2 or yet another resource provider. The
>>> workspace service would also provide some features on top of EC2
>>> (translating between PKI credentials and Amazon's paying accounts,
>>> contextualization as needed to make deployment dynamic). One
>>> application of interest for this was Swift. Last time we chatted
>>> about this though was in the context of using EC2 to provide a
>>> production platform for STAR runs (since virtualizing enough
>>> TeraPort to provide a production platform is taking a long time).
>>> This is what Tim and I are trying to make happen now.
>>>
>>> Since there was also interest in running Swift in VMs, Mike, Tibi
>>> and I met around February/March and agreed that a reasonable way to
>>> proceed will be for us to stand up a base virtual cluster somewhere
>>> locally (e.g., a static deployment on TeraPort) so that they can
>>> finish the configuration according to their needs, look at
>>> performance, figure out the best way to interact with it, and make
>>> sure that there are no VM-induced gotchas. All of this will be much
>>> easier to assess locally and on a static deployment. Then we'd make
>>> sure the cluster is dynamically deployable using the workspace
>>> service (on EC2 or whatever other provider). During the meeting (and
>>> over following emails) we agreed that the required "base cluster"
>>> would be configured with GRAM/Torque on the headnode plus a number
>>> of worker nodes, plus root privileges. We configured this cluster
>>> and it is ready to deploy. Are you saying now that in fact something
>>> different is needed?
>>>
>>> As Ian says, Borja and I were planning to meet with Ioan on Thursday
>>> to discuss interaction between Falkon and the workspace service (not
>>> necessarily/exclusively in the EC2 context). I don't completely
>>> understand the relationship between swift and falkon -- are there
>>> specific applications or scenarios that you are trying to target in
>>> this exercise?
>>>
>>> Ioan Raicu wrote:
>>>> Hi,
>>>> See below:
>>>>
>>>> Tim Freeman wrote:
>>>>> On Tue, 15 May 2007 16:20:03 +0000 (GMT)
>>>>> Ben Clifford <benc at hawaga.org.uk> wrote:
>>>>>
>>>>>
>>>>>> Ian asked about this elsewhere, but its perhaps interesting for
>>>>>> swift-devel people to look at the questions too.
>>>>>>
>>>>>> On Tue, 15 May 2007, Ian Foster wrote:
>>>>>>
>>>>>>
>>>>>>> Dear All:
>>>>>>>
>>>>>>
>>>>>>
>>>>>>> I asked Kate if she and Tim could look into creating VM images
>>>>>>> that would allow us to run Swift applications on Amazon EC2. I
>>>>>>> think Kate is meeting with Ioan about this on Thursday (?).
>>>>>>>
>>>>>>
>>>>>>
>>>>>>> One issue that I thought would be good to discuss is what we'd
>>>>>>> want in that VM image. Perhaps this is obvious to the rest of
>>>>>>> you, but it isn't to me. A few thoughts:
>>>>>>> * I'm assuming that we want to run "workers" on EC2 nodes,
>>>>>>> and have the
>>>>>>> "task dispatch" logic run on some external frontend system
>>>>>>> outside EC2.
>>>>>>> * I would think that we want to use Falkon to do the task
>>>>>>> dispatch. If so,
>>>>>>> we need a Falkon executor on each VM, configured to check in
>>>>>>> with the Falkon
>>>>>>> dispatcher. (Alternatively, we could use, say, SGE: in that
>>>>>>> case, we would
>>>>>>> want an SGE agent.)
>>>>>>> * We need a way of getting data to and from the worker
>>>>>>> nodes. Do we want to
>>>>>>> run a file system across the EC2 nodes and the external frontend
>>>>>>> node? That
>>>>>>> seems rather inefficient. Other options?
>>>>>>> * Should we preload the application code on each EC2 node?
>>>>>>>
>>>>>> Here's a couple of approaches:
>>>>>>
>>>>>> 1) swift regards all the EC2 nodes that we are paying for as a
>>>>>> single site.
>>>>>>
>>>>>> Something like falkon handles all the task dispatch and worker
>>>>>> node management. I don't know what that looks like at the moment
>>>>>> in Falkon, but the interface for Swift to send jobs into Falkon
>>>>>> sounds pretty straightforward and shouldn't need changing.
>>>>>>
>>>>> So if I understand, here there would be no gateway+LRM but each
>>>>> EC2 node +
>>>>> Falkon would need a port open to receive tasks? Or does each node
>>>>> pull down
>>>>> instructions OK from behind a firewall?
>>>>>
>>>> Falkon supports both polling and notifications. To use
>>>> notifications, there needs to be an open port on the worker :(
>>>>> Is there a latency problem with running each node as an indepdent
>>>>> task
>>>>> receiver with the dispatcher off-site from EC2? I would think it
>>>>> would be
>>>>> better to put the queues to fill with tasks on EC2 so it can more
>>>>> quickly get
>>>>> the task going when a node is done with a previous task (I may be
>>>>> missing some
>>>>> nuances here with respect to Falkon, don't know much about this
>>>>> yet!).
>>>> We have run the Falkon dispatcher at UChicago and workers at ANL
>>>> without any issues, so it can easily tolerate a few ms of latency.
>>>> We haven't tried it across 10s of ms of latency links, but my
>>>> instinct says that if you have enough workers, you might be able to
>>>> hide the latency. We'd have to experiment with it to see what
>>>> happens. We could potentially do some experiments between SDSC and
>>>> ANL over a 50+ ms link, and see what difference in throughputs we get.
>>>>
>>>> Ioan
>>>>> If a gateway node is desired, this option sounds a lot like the
>>>>> GRAM+LRM
>>>>> situation we use on VMs with the workspace service and will soon
>>>>> use on EC2 via
>>>>> the workspace EC2 gateway we're implementing. Start up one
>>>>> gateway node and
>>>>> then add compute nodes which dynamically join the pool, they are
>>>>> pointed to the
>>>>> GRAM node.
>>>>>
>>>>>
>>>>>> All the nodes in a site are required by our site model to have a
>>>>>> shared filesystem - we've talked about removing it, but I think
>>>>>> that is still the case and if so, isn't going to change soon.
>>>>> Setting up a shared filesystem in this environment is akin to
>>>>> setting up the
>>>>> compute nodes to join an LRM pool. The VMs can communicate over
>>>>> the private
>>>>> network at EC2, you can instruct EC2 to let all the nodes be open
>>>>> to each other
>>>>> (while simultaneously keeping a separate policy of blocking ports
>>>>> from being
>>>>> open from the internet and other people's EC2 nodes). The
>>>>> non-file-serving
>>>>> nodes would simply need to know the private address of the
>>>>> filesystem server
>>>>> (unless you are using a fancier network file system than NFS-style
>>>>> ones).
>>>>> For background: every VM on EC2 currently gets a public address --
>>>>> NAT'd to a
>>>>> private address which is actually what the VM's one NIC is
>>>>> configured with.
>>>>> There is a facility to open/forward specific network ports on the
>>>>> public
>>>>> address to each VM either via a group policy or on a VM by VM basis.
>>>>>
>>>>> [...]
>>>>>> Amazon also has a storage cloud, alongside its compute cloud. I
>>>>>> know very little about that and have never thought about how it
>>>>>> would fit into the above (if at all). Maybe someone else knows more.
>>>>>>
>>>>> A VM template on EC2 is called an AMI which stands for Amazon
>>>>> Machine Image.
>>>>> This is just a packaging thing but what it mostly means is that
>>>>> the VM is
>>>>> stored on S3 and also registered into the EC2 system.
>>>>>
>>>>> When starting an instance of an AMI, the file is copied from S3 to
>>>>> the
>>>>> hypervisor node (what we call propagation in the workspace
>>>>> service). After it
>>>>> is used, this file is deleted (an option in the workspace service
>>>>> but there is
>>>>> also an option to save it back with any changes). So the VMs are
>>>>> stored in S3 but anything that happens on them after being
>>>>> started is lost unless you manually do something about it.
>>>>>
>>>>> As for free scratch space, you get a good amount per node, 140G.
>>>>> But the node
>>>>> could go down at any moment just like a physical resource.
>>>>>
>>>>> To harness S3 for safely persisting any data (or if you need more
>>>>> space) you
>>>>> would need to actually run S3 clients on the VMs when they are run
>>>>> on EC2. You
>>>>> could alternatively mirror data between nodes assuming that all
>>>>> would not go
>>>>> down at once.
>>>>> The good thing is that you do not pay transfer costs between S3
>>>>> and EC2 if you
>>>>> chose to use S3 for big storage, you would only pay the "housing
>>>>> fees" so to
>>>>> speak.
>>>>> Tim
>>>>> _______________________________________________
>>>>> Swift-devel mailing list
>>>>> Swift-devel at ci.uchicago.edu
>>>>> http://mail.ci.uchicago.edu/mailman/listinfo/swift-devel
>>>>>
>>>>>
>>
>
--
Ian Foster, Director, Computation Institute
Argonne National Laboratory & University of Chicago
Argonne: MCS/221, 9700 S. Cass Ave, Argonne, IL 60439
Chicago: Rm 405, 5640 S. Ellis Ave, Chicago, IL 60637
Tel: +1 630 252 4619. Web: www.ci.uchicago.edu.
Globus Alliance: www.globus.org.
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