Postgres Performance - Read Only

Continuing the PostgreSQL Performance series:

Please read more about Test Particulars / Chart Naming methodology from the previous post in the series.

Takeaway:

• Read-Only Performance numbers have consistently grown from (at least) 9.1 onwards
• 9.5 Branch is 35%-50% faster than 9.1 Branch

Postgres performance - File + ReadOnly

Just wanted to see how Postgres performed when comparing its performance over the different Major releases. I had a spare Pi2 lying around and found it useful for such a performance test.

More inferences to follow, in future posts.
As always, any feedback is more than welcome.

TLDR:

• Despite a regression in 9.3 onwards, the combination of File + Read-Only has improved drastically in the 9.6dev branch
• 9.6dev branch is 
• 2x faster than 9.1 on some tests
• 50% faster than 9.5.2 (currently, the latest stable release!) on some tests
• Yay!!

Hardware:

• Raspberry Pi Model 2B
• 1GB RAM
• 900 MHz Quad-Core-ARM Cortex-A7 (ARMv7 Processor rev 5 (v7l))
• 32GB Class 10 SD Card

Software: Source used for this test

Note:

1. All configurations were run 10 times each
2. All configurations were run for 100 secs each
3. The Phrases in the name of each chart tells what Pgbench was run with:
1. ConnX: with -cX (For e.g. Conn64: with -c64)
2. Thread4: with -j4
3. Prepared: with -M Prepared 
4. File: External SQL file with one SQL command "SELECT 1;"
5. Readonly: with -S
6. 100secs: with -T 100

Getting my hands on a Google OnHub

So finally, I get to lay my hands on the new Google OnHub at home.

Unlike its other Google cousins, the OnHub isn't yet available for sale in India and then its a niche product (yet) here in India. The other obvious question is whether you'd pay 6x the price for a router, even when a brand like Google sports it.

I think I would and so was finally able to put my foot down when I realised that I had had enough of other routers making things difficult at home.

A few features I liked:

• Automatic Software update
• I loved this aspect that is pretty much missing in all its contemporaries
• Considering that my 10 year old D-Link 502T hasn't received a single firmware / OS update I was scared to death what all crapware was running on my Home WiFi a month back.
• That coupled with a few Einsteinish Router companies forced to admit secret (idiotically planned) backdoors, it just isn't funny to realise that my Home Router was probably a 'piece of cake' for a script kiddie trying to login.
• Prioritize a phone
• Again its a pleasure showing it to my wife how easy it is for her to prioritize her phone, when the kids are watching YouTube in HQ.
• Router configuration a breeze
• Its super simple to manage
• I just recently got a Chromebook for Audio replacement working at home, and it was pleasant to realise that setting static IP address wasn't about setting /etc/network/interfaces anymore. The PI2 stayed on DHCP and I set the OnHub to give the MusicBox a static IP hereon... QED :) !
• Manage your OnHub from China!

• Once configured, you could manage your router sitting hundreds of miles away!
• Which basically means no long calls to your GrandMa asking her to read out what is on the screen when she types 'http://192.168.1.1' on the browser.
• You could be managing multiple OnHubs on your phone, each sitting at your parents place hundreds of miles away (without VNC / TeamViewer / RDP hacks) and still configure every minute detail such as setting Port-Forwarding / DNS / DHCP etc. from your SmartPhone.
• WiFi connection optimization
• Frankly, with so many walls, some remote corners of my house have seen some network quality degradation at times, but I haven't seen a 'No Network' message yet. So probably its doing a good job there, but I am sure I can't tell that right away.

Add to that, if we consider that this machine is a dual core machine (with a GPU) most of which isn't even put to use (yet), I am pretty excited to know what its real potential is and how Google upgrades my 'boring router' down the line.

Rumour is that this might just be a Google's shot at an Echo or a Siri sitting in your drawing room. But till that happens, I'd have to stay pleased with a beautiful router sitting on the desk :)

Now you may want to get paranoid and all and worry about how Google could keep an eye on Dr. Lanning (you), but I have a feeling that it'd take a while before I give breadcrumbs to a Detective Spooner.

All in all, a (pretty) costly router upgrade but I ain't regretting it.

MusicBox + Pi1B + Ancient 4.1 Speakers => Chromecast for Audio

Since Chromecast-for-Audio hasn't yet been launched in India, eBay sellers are using near monopoly extra for such a device here. Frustrated with being blackmailed like this, I resorted to conjuring up a combo that finally gave some shape to my 2 year old Pi and a ten year old 4.1 music system a life, and gave a good groove to my (otherwise boring) drawing room :) !
to charge a painful 150%

Parts:

• Any Raspberry Pi
• Except PiZero
• Too low powered, would not work
• To clarify, either of the following combos would work
• The old PiA+ / PiB+
• with SD Card
• 2GB or more
• The newer Pi2
• with MicroSD Card
• 2GB or more
• MusicBox
• Win32DiskImager
• Client Operating Sytem
• (Desktop) Windows
• Bonjour
• Optional
• Makes the URL easier
• I had Apple iTunes that install Bonjour support by default
• (Smartphone) Android
• Doesn't support Bonjour out of the box
• Alternative,
• Get the Pi to come with constant IP address
• Very easy with my new OnHub
• Bookmark the URL instead
• Volume Control
• The Web Interface allows changing volume
• From the command line you could try this
• amixer cset numid=1 -- 80%

Happy Listening :) !

Reverse Port Forwarding and how !

Recently had to work on a PoC that required spinning off Docker instances with custom configurations. The problem wasn't as much with the Docker aspect, which is probably up for another story sometime, as much as the fact that as luck had it, we couldn't commission a separate machine for this PoC, and I eventually had to do the entire development inside a 2G VirtualBox VM on my 8G Laptop.

The tricky part was that we had to submit the URL to the PoC Landing Page even before it could be ported to a full-fledged VM/server.

So effectively, we:

• Submitted a URL (on ServerA) running Apache, but no space to host a 40G VM.
• Had a Laptop where the VM was developed, but can't stay online since its not always connected
• Had another server (ServerB) where the VM needs to be ported, to be always up for PoC evaluation
• ServerA was in the US, whereas, ServerB (& Laptop) are half-way across the world in India.

Separately, the VM was an Ubuntu installation that had the following:

• A running NodeJS (Bootstrap / Express combo) serving the PoC GUI
• Separately it hosted the docker runtime that spun off Docker instances that had their own propietary application + Tomcat running on port 8080, all of which eventually supposed to be visible company-wide
• Thirdly, it had a PostgreSQL 9.3 database that served as a backend to all the running docker-based app instances

To connect ServerA with the PoC hosted on ServerB we tried the following:

• Creating VirtualHost entries on the ServerA that pointed to corresponding ports on the VM
• This failed because the VM was running inside a NATted configuration and thus was invisible to ServerA
• Then we tried an alternate solution, wherein Apache->VirtualHost entries on ServerA were pointed to port 80 on ServerB. This required port-forwarding port 80 on ServerB to port 3000 (NodeJS) on ServerB. Although for this we used NetSH, this failed for various reasons, some of which we could identify and some we couldn't. For e.g. we installed the ipv4 module for NetSH, also tried installing ipv6, as well as, enabling Windows Firewall for NetSH to work (contrary to popular belief that Windows Firewall might be the reason for things getting blocked)
• We finally settled down to running persistent SSH connections directly from the VM to ServerA (thereby by-passing all Windows Firewall issues) and setting up Remote Port-Forward such that remote ports could connect to Node Server inside the VM
• This too initially didn't work as expected. To identify the cause we:
• isabled SELinux on ServerB, then ServerA (although that didn't make sense) as well as on the VM to no avail
• Then we disabled IPTables on all the relevant machines and that still didn't help
• Finally we realised that the Remote Port-Forwarding though working well, was getting attached to the localhost interface on ServerA. Which means that although 127.0.0.1:80 on ServerA was working as expected, 192.168.1.1:80 on the same server immediately gave a "connection failed". It took a while to realise that though I was logging in trans-atlantic, the immediate 'Connection Failed' was an issue with ServerA and not with this side of the line.
• What complicated things post that was that the regular -g option was insufficient. It required setting the GatewayPorts on the SSHD (with a sshd restart) to work as expected.

Eventually, after a few hours of transatlantic jugglery, finally got a working URL that looked something like this... What a day !

Pigz - Parallel GZip

For a while, I've been frustrated with the fact that GZip was unable to consume idle CPUs on my laptop. Recently read about PIGZ (a drop-in GPL replacement) that implicitly consumes all CPUs.

Pronounced Pig-Zee, PIGZ is a drop-in replacement for GZIP and automatically consumes all CPUs of the host machine in order to get the compression completed much faster.

OLD: tar -cf - sourcefolder | gzip > sourcefolder.tar.gz

NEW: tar -cf - sourcefolder | pigz > sourcefolder.tar.gz

Enjoy!

Using Pi as an home-based Media Server

This is among a series of articles on my experience with the Pi.

This article is about using a Pi as a primitive low-end File-Server for your home network:

Expectations:

• Torrent-Server
• Download Torrents
• Store on a File-Share
• Windows Share
• Serve the File-Share as a Windows Share Drive
• Allow Read / Write to this Windows Share Drive
• Use File-Share as Media-Server
• Using any Smartphone / Laptop
• Play Movies using VLC
• View all Photos / Home-Videos

Effectively:

1. Always on
1. Always accepting new Torrent requests
2. Instantly start downloading 
2. In Real-time
1. Allow user's to view torrent download status
3. Use any UPnP Phone App to play Video content over WiFi on a SmartPhone
4. Use VLC (Network Streaming) to play any Video over WiFi on Laptop / Desktop
5. Use Windows Share Drive and view all Photos / Home-Videos as needed

How-To:

• On Server
• Install Torrent-Daemon
• Configure Torrent-Daemon to listen on RPC requests
• Here's the howto for that
• Configure Samba
• Set the Download folder to be shared
• On Windows
• Install Transmission-GUI-Remote
• Desktop / Smartphone
• Configure GUI to use the RPC based Torrent-Daemon server
• Make this application the default for .torrent & magnet files
• On Linux
• Install Transmission-Remote
• sudo apt-get install transmission-remote
• Configure that to use Daemon (instead of downloading directly with transmission-cli)

Pros/Cons:

• Pros
• Once torrent download has begun, client can disconnect / shutdown client computer
• Server continues to get torrents, after a restart
• miniDLNA serving speed pretty decent
• Watching a movie (over WiFi) on VLC
• CPU ratio barely 0.01 which is pretty decent
• Should be able to easily serve a small army :)
• If no other IO is happening
• If WiFi isn't the bottleneck 
• Cons
• Storage on Pi needs to be managed from time-to-time
• Currently is highly adhoc based
• Truly taking RAID concept to heart!!
• Have 6 Pen Drives (ranging from 4GB to 16GB)
• 8GBs are INR ~170 ( $3 )
• All connected via 3 USB Hubs (both USB 2.0 and USB 3.0)
• One Powered, two non-powered hubs
• Most on Btrfs
• Pretty stable, surprising that still get 1+ MBps with Pi's CPU
• Some VFAT fs since have need of moving stuff off of Pi to a Windows Laptop
• All mounted under /disk
• Very temporary arrangement
• Ideally am looking for a LVM solution (which allows me to remove / add pen-drives on the fly and thus can be called as one) that actually is suited for this purpose.
• But miniDLNA picks up Photo / Audio / Video pretty well from all different mounted folders
• Download speed limitations
• Internet Speed = 2 MBps
• Daemon Download speed capping = 1Mbps
• But PI never reaches it :D !
• Just imagine the poor configuration
• Pi + Btrfs + USB 2.0 + 3 USB Chain + Unpowered Hub
• Still consistent at 450kbps! Impressive!
• Lack of Transmission-Daemon configuration tool means all configuration has to be done via black-screen configuration files
• Careful configuration
• Give all access to 'all' users only if you're sure that all users are going to be careful