[Swift-devel] swift-on-ec2
Ioan Raicu
iraicu at cs.uchicago.edu
Wed May 16 12:15:07 CDT 2007
Kate Keahey wrote:
>
>
> 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.
If someone (Kate, Borja, Ian, anyone) has an account on EC2 and S3 so we
can try a demo run tomorrow, I think it would be very beneficial! Do we
have images created that would run on EC2? Can we easily modify them so
we can include the necessary software, or at least once we start them
up, we can upload the necessary software needed b Falkon (JVM, Falkon
executor, some GT4 libraries).
>
> 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?
Falkon relies on LRMs to get resource allocations, and bootstrap. We
have not interfaced with any specific LRMs, but use GRAM to abstract
this away.
>
>>
>> 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
>>>>
>>>>
>>
>
--
============================================
Ioan Raicu
Ph.D. Student
============================================
Distributed Systems Laboratory
Computer Science Department
University of Chicago
1100 E. 58th Street, Ryerson Hall
Chicago, IL 60637
============================================
Email: iraicu at cs.uchicago.edu
Web: http://www.cs.uchicago.edu/~iraicu
http://dsl.cs.uchicago.edu/
============================================
============================================
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