dhis2-devs team mailing list archive

[deemoyes@xxxxxxxxx]

Yes, you are very correct, that's exactly what VMWare can also help achieve. Doing load balancing.

Α well configured machine can handle up t̶̲̥̅̊ợ̣̣̇̇̇ 50 VMWare depending on your licensing and like you said, two different Machines can be used physically for replication and data safety for Disaster Recovery purpose.
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-----Original Message-----
From: Orvalho Augusto <orvaquim@xxxxxxxxx>
Date: Wed, 1 May 2013 16:07:12 
To: Dayo Adeyomoye<deemoyes@xxxxxxxxx>
Cc: Lars Helge Øverland<larshelge@xxxxxxxxx>; DHIS 2 developers<dhis2-devs@xxxxxxxxxxxxxxxxxxx>; dhis2-users@xxxxxxxxxxxxxxxxxxx<dhis2-users@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Dhis2-devs] [Dhis2-users] Server specifications

It is true that hardware prices have decreased a lot.

But for me it seems too excessive these recommendations. So I am wondering
how we arrived to these recommendations. Would be nice if we share that.

And for professional solutions it is not only one big machine you buy. You
must have two. So when one dies you have the other ready.

Some other things to be tried are:
Instead of using one big muscular server you might need to consider to use
one machine for webapplication and other database.

And the webapplication server actually can be a group of machines doing it;
And for databases you can have just one machine for writing queries which
is master to other servers that are only queried for reading only (this for
MySQL have been done) or other high availability solution.

For the tools to study your server, let me add some more:
- top - The basic to see the processes and CPU usage

- vmstat - This is verry important to see how your server is using the
memory. Repeat it and check our the blocks are being used.

- plotting tools based on snmp may help to profile your server; To see
correlations between traffic/connections and CPU or memory. So you can
consider what to change.

Hope it helps.

Caveman





On Wed, May 1, 2013 at 12:21 PM, Dayo Adeyomoye <deemoyes@xxxxxxxxx> wrote:

> Yes you are right, hardware prices are coming down plus a very good server
> can run VMWare to properly allocate resources
>
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>   ------------------------------
>  *From:* Lars Helge Øverland <larshelge@xxxxxxxxx>
> *To:* DHIS 2 developers <dhis2-devs@xxxxxxxxxxxxxxxxxxx>; "
> dhis2-users@xxxxxxxxxxxxxxxxxxx" <dhis2-users@xxxxxxxxxxxxxxxxxxx>
> *Sent:* Wednesday, May 1, 2013 11:16 AM
> *Subject:* [Dhis2-users] Server specifications
>
> Hi all,
>
> in version 2.11 and later DHIS performs aggregation on-the-fly as opposed
> to pre-aggregating data into data marts.
>
> This raises the bar a little on your server's specifications, mostly in
> terms of available RAM and disk read speeds.
>
>
> Some rules-of-thumb server recommendations:
>
>
> - RAM: At least 1 GB memory per 1 million captured data records per month
> or per 1000 concurrent users. At least 4 GB for a small instance, 12 GB for
> a medium instance.
>
> - CPU cores: 4 CPU cores for a small instance, 8 CPU cores for a medium or
> large instance.
>
> - Disk: Ideally use an SSD. Otherwise use a 7200 rpm disk. Minimum read
> speed is 150 Mb/s, 220 Mb/s is good, 350 Mb/s or better is ideal.
>
>
> So we encourage you to invest in appropriate hardware to continue to
> benefit from all the new features in DHIS. Hardware prices are coming down
> and value for money is increasing at vps' like linode <http://linode.com/>
>  and digitalocean <http://digitalocean.com/>.
>
>
> regards,
>
> Lars
>
> -----
>
> PS. For server admins, here are some tips to measure hard disk/drive read
> speeds on Linux:
>
> - Use the hdparm utility which will give you approximate read speed:
>
> sudo hdparm -Tt /dev/sda
>
>
> - If you are on a virtual server image without /dev/sda you can generate a
> random file and test write and read speed like this:
>
> dd if=/dev/zero of=testfile bs=4k count=2000000
>
> dd if=testfile of=/dev/null bs=4k count=2000000
>
>
> - To do a real-life test, you can install iotop (sudo apt-get install
> iotop) and run it with
>
> sudo iotop
>
> then start DHIS in a new terminal and load a very large pivot table, then
> monitor read speed from iotop. You should be seeing read speeds around 12 -
> 25 Mb/s. Be aware that database queries will be cached after some time.
>
>
>
>
>
>
>
>
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