dhis2-devs team mailing list archive

[Jason Pickering <jason.p.pickering@xxxxxxxxx>]

Another experiment I conducted over the weekend was a hybrid approach.
Linnode seems to be quite good at being persistent and is relatively
cheap.  I think the draw back is of it is  not at all as easily
scalable as Amazon. I tried a setup where I use a Linode as the
backend DB and then a cluster of AWS instances(which acted as the
DHIS2 frontend)  connected to the remote Postgresql database (running
on Linode). Obviously, latency is an issue here as packets have to get
out of Amazon and to Linode and back, but I guess these pipes are
pretty big.

The experiment worked quite well. Again, not really sure if this
architecture would be advantageous, but perhaps it would be a simple
way to scale up and down capacity depending on peaks of usage (for
instance during the data entry period). Would be nice to test if we
could. Did any one ever come up with a way to do load testing on DHIS?
I heard rumors about Selenium or Jmeter, but not really sure if there
is anything out there.

Regards,
Jason


On Sun, Mar 13, 2011 at 2:43 PM, Jason Pickering
<jason.p.pickering@xxxxxxxxx> wrote:
> On Sun, Mar 13, 2011 at 2:18 PM, Jo Størset <storset@xxxxxxxxx> wrote:
>> Took it off-list, but maybe others are also interested?
>
>
> Oops.
>
>
>> Den 13. mars 2011 kl. 10.54 skrev Jason Pickering:
>>
>>> Looking more into costs, it seems to be quite significant. Costs are
>>> calculated based on instance-hour. If it is up and running, it is
>>> billed.  Testing on a Micro instance proved that performance is pretty
>>> unacceptably slow. Scaling up to an instance with 17 GB of memory
>>> improved things significantly. Latency with the RDS service seems
>>> significant but could be related to the relatively small size of the
>>> database (5 GB). Keeping an instance up and running 24X7 for a month
>>> will cost you several hundred bucks it seems, significantly more than
>>> Linode.
>>
>> How did you go about calculating this? Linode is comparable to running EC2 without RDS, I guess, I get $ 87.84/month for a one year large reserved instance, that is
>
> There is a cost calculator..http://calculator.s3.amazonaws.com/calc5.html
>
> and I was reading this.
>
> https://forums.aws.amazon.com/message.jspa?messageID=114409
>
>>
>> What - Linode - EC2
>> ----
>> Price - $159.95 - $ 87.84
>> Memory - 4096MB - 7.5 GB
>> Disk - 128GB - 850 GB
>> Processing - ? - 4 EC2 Compute Units (1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor)
>
>
>
>> It is a bit difficult to compare, but I'm not sure amazon don't make sense even for stand-alone instances. And for flexibility and services offered, especially if running >several services in coordination, it certainly seems to make sense. While a micro instance has "low" IO performance a  large instance has "high" IO performance, so >I think your latency issues might go away as well...
>>
> The interesting thing is that the MicroInstances with the RDS backend
> actually work quite well for data entry, which is the main use case
> for me considering Amazon (and various regulatory issues). I am
> thinking that if we created a stripped down version of the DHIS war,
> which consisted only of the stuff needed by data entry personell,
> micro instances which are easily created and load balanced could serve
> as a powerful way to scale up and down based on demand. This is of
> course possible as well with LinNode, but it is just so easy on Amazon
> to do this. I doubt going to support things like the data mart, import
> and other memory hungry tasks, but it is simple to create a new
> (temporary) instance which could be used for these "heavier" tasks.
>
>> Am I missing any significant details?
>
> I am not sure at this point. I think we need to do some testing.
>
>>> If you want to test yourself, give me your Amazon WS customer ID, and
>> I will make the AMI available to you.
>
> Done. Obviously, there are some issues related to the RDS backend.
> THis is obviously connected to my instance, which I assume you should
> have no authority for. It would be nice to have a stripped down AMI
> with just Tomcat and HTTP (for the reverse proxy). Might perform
> better. It seems you can import virtual machines into Amazon  as well,
> but have not figured out this part yet. :)
>
> Regards,
> Jason
>
>
>
>
>
>
> --
> Jason P. Pickering
> email: jason.p.pickering@xxxxxxxxx
> tel:+260974901293
>



-- 
Jason P. Pickering
email: jason.p.pickering@xxxxxxxxx
tel:+260974901293