Building a good Software Startup

If I were to build a good software startup today, I'd run with the following ideas.

Hire only good people who get things DONE.
Even if they are more expensive in terms of compensation.
Quality trumps numbers. No doubt about it.

Development Team

• 1 Lead Developer
• 1 Senior Developer
• 2 Junior Developers
• 2 Business Analyst/QA

Operations Team

• 1 Lead Systems Admin
• 1 Senior System Admin
• 6 Junior System Admins

Give your team a quiet working environment with ergonomic furniture and equipment

Give your team good internet connection

• the faster they can download their installers, the earlier they can start working on code
• the faster they can look up the solution on google or stackoverflow, the faster they can proceed to the next problem

Give your team good computer hardware

• at least dual core processors with virtualization support
• at least 8GB memory
• at least 2 hard drives for mirror setup
• at least 2 screens

Make sure to have enough environments to test, deploy and support the system properly.

• Development Environment
• Staging Environment
• Support Environment
• Production Environment

Make use of Free or Open Source systems to manage the development process.
Buy a commercial product only if you can't find a solution that fits.

Project/Issue Tracking with Source Code Management Options:

• Indefero
• Gitorious
• Gitlab
• Redmine+gitolite

Continuous Integration Server Options:

• Jenkins
• Team City

Code Quality:

• Sonar

Setup google apps for for email, calendar and other stuff

As an example, here is how I would set it up on three physical servers:

Server#1 running ProxmoxVE
- Firewall/Proxy Server/Package Cache(apt,yum,mvn) VM
- Redmine+gitolite VM
- Jenkins VM
- Sonar VM
- NFS/Samba Server VM

Server#2 running ProxmoxVE
- Development Environment VM
- Staging Environment VM
- Support Environment VM

Server#3 for storage of backups
- nexentastor or freenas or centos+zfsonlinux

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ProxmoxVE 2: Configuring DRBD

I am running ProxmoxVE 2.0-35/d07f49c3 on two nodes connected using a cross cable on gigabit nics.
host1 ip: 10.0.10.201
host2 ip: 10.0.10.202

Check if drbd module is available

modprobe -l | grep drbd

Check if drbd module is loaded

lsmod | grep drbd

If not, load it with

modprobe -v drbd

Check the module version

modinfo drbd | grep version

I installed the appropriate drbd8-utils package on both nodes

dpkg -i drbd8-utils_8.3.10-0_amd64.deb

I built my own deb from source. You can find my build here.

I shrank the data volume on both of
I made use of the extents I freed up by shrinking the data volume to create an lvm volume that will be used for drbd.

lvcreate --verbose --extents 50000 --name lv4drbd pve

Next I modified /etc/drbd.d/global_common.conf so that it only contains:

global {
    usage-count no;
}
common {
    protocol C;
    syncer {
        rate 30M; 
    }
}

Next I created a new resouce file /etc/drbd.d/drbd0.res

resource drbd0 {
    protocol C;
    startup {
        wfc-timeout  0;
        degr-wfc-timeout 60;
        become-primary-on both;
    }
    net {
        cram-hmac-alg sha1;
        shared-secret "drbd0-secret";
        allow-two-primaries;
        after-sb-0pri discard-zero-changes;
        after-sb-1pri discard-secondary;
        after-sb-2pri disconnect;
    }
    on host1 {
        device /dev/drbd0;
        disk /dev/pve/lv4drbd;
        address 10.0.10.201:7780;
        meta-disk internal;
    }
    on host2 {
        device /dev/drbd0;
        disk /dev/pve/lv4drbd;
        address 10.0.10.202:7780;
        meta-disk internal;
    }
}

I added the IP address of the other host into each of the /etc/hosts files.

Next I started drbd on both nodes with

/etc/init.d/drbd start

I then initialized drbd metatdata on both nodes with

drbdadm create-md drbd0

Next I brought up the device on both nodes with

drbdadm up drbd0

I checked the status on both nodes with

drbd-overview

Next I started synchronization(should be instantaneous) from one node with

drbdadm -- --clear-bitmap new-current-uuid drbd0

Lastly, I restarted the drbd service on both nodes to enable Primary/Primary operation

/etc/init.d/drbd stop
/etc/init.d/drbd start

I hope you found the post useful. You can subscribe via email or subscribe via a feed reader to get relevant updates from this blog. Have a nice day.

ProxmoxVE 2.0: Shrinking the data volume

After installing ProxmoxVE 2.0rc1, a data volume was created which makes use of most of the space on the drive.

I wanted to carve out a separate volume for some other use so I needed to shrink this data volume:

First, I unmounted the logical volume with:

umount /var/lib/vz

Then I proceeded to shrink the file system to the minimum size possible with:

resize2fs -Mf /dev/pve/data

Then I proceeded to reduce the size of the logical volume with:

lvreduce --verbose --extents -100000 /dev/pve/data

Then I proceeded to grow the file system back to occupy the now reduced volume with:

resize2fs -f /dev/pve/data

Lastly, I remounted the file system with:

mount /dev/pve/data /var/lib/vz

I hope you found the post useful. You can subscribe via email or subscribe via a feed reader to get relevant updates from this blog. Have a nice day.

FizzBuzz in Javascript

Joel and company probably won't hire me since he only gets rockstar developers but here is my attempt at FizzBuzz

<script>
    for(var i=1;i<=100;i++){
        if(i%3 != 0  && i%5 != 0)
            document.write(i);
        if(i%3 == 0)
            document.write('Fizz');            
        if(i%5 == 0)
            document.write('Buzz');                    
        document.write(' ');
    } //end for loop
</script>

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dailyLooper bash script

We needed to regenerate some data for the data warehouse so I had to run an extraction script once for each day of the month.

I wrote a simple bash script to make it easier to run a command or other scripts once for every day of a target month and year.

Code can be found below but may also be downloaded from here.

#!/bin/bash
usage(){
    echo "Usage: dailyLooper <year> <month> <script to run>"
    echo "Each date in the given month will be passed into the script in yyyy-mm-dd format"
}


CURRENT_MONTH=$(date +%m)
TARGET_YEAR=$1
TARGET_MONTH=$2

if [ "$#" -lt 3 ]; then
    usage
    exit 1
fi

if [ "$3" = "" ]; then
    SCRIPT="echo"
else
    SCRIPT=$3    
fi

#returns the date yesterday if target month is the current month
#otherwise returns the last date for the target month
lastDayOfMonth(){
    local _year=$1
    local _month=$2   
    if [ $_month -lt $CURRENT_MONTH ]; then
        echo $(date -d "${TARGET_YEAR}-${TARGET_MONTH}-01 + 1 month - 1 day" +%d)
    else
        echo $(date -d "yesterday" +%d)
    fi    
}


main(){
    local _lastDay=$(lastDayOfMonth $TARGET_YEAR $TARGET_MONTH)
    i=1
    while [ "$i" -le $_lastDay ]
    do
        local _date=$(date -d "${TARGET_YEAR}-${TARGET_MONTH}-${i}" +%Y-%m-%d)
        $SCRIPT $_date
        ((i++))
    done #end day of month loop
}

main

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