September 2010 Archives

After quite a few months we are finally past the planning stage and starting to build something. I am very happy with the progress we are making so far.

We bought two 4x8 foot sheets of 5/8 inch thick particle board and had Lowes cut them in half for us to make it easier to transport them home with us. Our quick white board sketches told us we wouldn't be gaining any useful pieces of board by keeping them whole. We will definitely have no problem at all making the entire cabinet out of these two 4x8 sheets of particle board.

Cutting the Slots

Cutting the slots in the boards with the table saw was easier than either of us expected. The first set of slots we cut were extremely snug and it was VERY solid when we assembled it most of the way. We were worried that it would be too hard to disassemble later on if we ever have to move the table so we cut the slots a bit wider. We took off about a half-saw-blade worth of material off the outside of each slot.

It slides together much more freely now but it still does a very good job of keeping itself square.

We cut shorter slots in the sides to mount the control panel boards. We probably made two minor mistakes here. We should have cut these slots to be very snug and we didn't really leave enough room for the slots on the skinnier sides to get much bite. We'll just end up having to use some screws to keep the control panels in place.

I'm very happy with the progress so far. We have about four hours invested so far. I certainly didn't expect to get the rough control panel boards cut and fitted so quickly.

The Next Steps

The next time we get a chance to work on it we will probably be mostly making cuts with a jigsaw and sanding.

We are going to cut the corners on the control panels round. We also want to cut some curves into the outsides of the "legs." We think it will look better if it isn't just a square pound-sign-shaped box.

We are also going to cut out some of the bottom of the box to make a bit of extra room for feet and legs. We aren't three and a half foot tall eight year old kids eating pizza and playing games in an arcade anymore. Now we're six foot tall adults eating pizza and playing games at home and we need to be comfortable!

Hopefully we will be able to make time to work on it for another few hours within the next week or two.

When I upgraded to a new laptop I also upgraded back to a dual head setup with a pair of external monitors. I don't need the laptop to be sitting in the middle of my desk anymore so I wanted to find somewhere I could park the laptop, preferably out of site.

I picked up four larger PVC J hooks from Lowes for less than a dollar each. I'm pretty sure I used the 1.5 inch size hooks for this.

I screwed two of them to the desk with the J side facing down. This makes the floor the laptop sits on. I screwed one more into the desk with the J side facing up. This one keeps the laptop from tipping out of its little cradle.

I cut the third one down to about one third of its original length. I screwed that one into the desk perpendicular to his other three friends being careful to position it so that it didn't block any of the ports on that side. His job is to make sure I don't just slide the laptop straight through, out the back, and onto the floor...

After it was already in place I realized that it is probably a good idea to have the front hook mounted a tiny bit higher than the rear hook. That way gravity would hold the laptop up against the smaller hook.

I have a can of black vinyl dye here. My plan is to spray the hooks and my DIY monitor stand black. I've been putting it off because I'll have to take down the monitors and the laptop for a day or two. One problem is that I don't want to be without my monitor and laptop stands for a few days. The other problem is that I can't see any of the PVC from where I'm sitting. I barely realize it isn't painted.

Update 2010-11-06:

I finally got around to spraying the laptop rack with vinyl dye and I added a picture of the finished product. It looks much better now and it doesn't stand out nearly as much as it did when it was bright white.

I was running btrfs for almost a month before I got around to setting up some automated snapshotting. I was expecting to have to write some scripts of my own but I luckily I found btrfs-snap. All you have to do is pass btrfs-snap the path of the volume to snapshot, a tag for the snapshot (daily, weekly, etc), and the number of snaphots to keep. It stores the snapshots in a .snapshot directory at the root of the volume and names the snapshots using the tag and a time stamp.

I have mine set up to keep 4 weekly snaphost, 7 daily snapshots, and 24 hourly snapshots. I also tried keeping a dozen five minute snaphots (fivers). Things got gummed up when I tried that and I had dozens of snapshots processes sitting around idling. I could probably get around that issue by the making sure only one snapshot job is running at any given time.

Here's my cron scripts:

 wonko@zaphod:~$ cat /etc/cron.hourly/btrfs-snap 
 #! /bin/bash

 /usr/local/bin/btrfs-snap / hourly 24
 /usr/local/bin/btrfs-snap /home hourly 24
 /usr/local/bin/btrfs-snap /home/wonko/wip hourly 24


 wonko@zaphod:~$ cat /etc/cron.daily/btrfs-snap
 #! /bin/bash

 /usr/local/bin/btrfs-snap / daily 7
 /usr/local/bin/btrfs-snap /home daily 7
 /usr/local/bin/btrfs-snap /home/wonko/wip daily 7


 wonko@zaphod:~$ cat /etc/cron.weekly/btrfs-snap
 #! /bin/bash

 /usr/local/bin/btrfs-snap / weekly 4
 /usr/local/bin/btrfs-snap /home weekly 4
 /usr/local/bin/btrfs-snap /home/wonko/wip weekly 4
 wonko@zaphod:~$

And here is a set of snapshots:

 wonko@zaphod:~$ ls /home/.snapshot
 daily_2010-09-04_07:43:13   hourly_2010-09-12_00:17:01
 daily_2010-09-05_07:28:22   hourly_2010-09-12_01:17:02
 daily_2010-09-06_08:05:00   hourly_2010-09-12_02:17:01
 daily_2010-09-09_06:44:39   hourly_2010-09-12_03:17:02
 daily_2010-09-10_08:00:54   hourly_2010-09-12_04:17:01
 daily_2010-09-11_07:59:08   hourly_2010-09-12_05:17:03
 daily_2010-09-12_07:51:40   hourly_2010-09-12_06:17:01
 hourly_2010-09-11_13:17:01  hourly_2010-09-12_07:17:01
 hourly_2010-09-11_14:17:02  hourly_2010-09-12_08:17:02
 hourly_2010-09-11_15:17:02  hourly_2010-09-12_09:17:02
 hourly_2010-09-11_17:17:02  hourly_2010-09-12_10:17:01
 hourly_2010-09-11_18:17:01  hourly_2010-09-12_11:17:01
 hourly_2010-09-11_19:17:01  hourly_2010-09-12_12:17:02
 hourly_2010-09-11_20:17:01  hourly_2010-09-12_13:17:01
 hourly_2010-09-11_21:17:02  weekly_2010-09-02_07:51:13
 hourly_2010-09-11_22:17:01  weekly_2010-09-09_16:00:25
 hourly_2010-09-11_23:17:02  weekly_2010-09-12_07:52:39

Everything has been running fine for about a month. I haven't filled up my disk with junk snapshots yet. One of the nice things about these writeable snapshots is that I can always prune big files that I don't need right out of them.

There aren't very many good Bluetooth mice on the market. One of my favorites is the Logitech V270. It is big enough to use but still small enough to be portable. It also sips on batteries and lasts for months on a pair of AA batteries. Unfortunately it is absolutely useless for playing FPS games. It goes to sleep after a very short time period. It wakes up fast enough that you won't notice it when you're just clicking around on your desktop, but if you duck behind a corner to wait for an unsuspecting victim you will certainly notice the time it takes for the V270 to wake up...

Choosing a Mouse

There wasn't a big selection of Bluetooth mice 3-4 years ago and I don't want to carry a dongle when my laptop already has Bluetooth. I ended up buying a used and discontinued Logitech MX900 on eBay. It is a fine mouse even if it is a little on the heavy side. Unfortunately it drains a pair of AA batteries in two or three days and lacks a power switch.

This wasn't a big deal until I stopped using the laptop display and switched to a pair of external monitors. I used to just use the touchpad, now I have to use a mouse...

Why Do I Need the Dock?

The Bluetooth module in my current HP Pavillion dv8t laptop is rather underpowered. The signal is so bad that my mouse is very jittery when the laptop is it its hiding spot behind my desk (my old Dell Inspiron 6400 didn't have this problem at all). The poor signal and the need for a battery charger were two good reasons to dig out the dock that came with the MX900.

I'm convinced that Logitech has absolutely no idea how to make a decent charging cradle. I was going through all sorts of contortions and dances trying to get the mouse to actually start charging when I placed (or slammed) the mouse into the cradle. I'm also lucky if it continues charging after I walk away... We have the same sort of problem with our Logitech Harmony 880 remote control, I might have to try this on him as well.

How Did I Fix It?

My fix was quick, easy, cheap, and quite ugly... I made two short cylinders out of aluminum foil that matched the diameter of the little charging contacts on the cradle. Then I just put them over the contacts and mashed them down in there. They may not look pretty but they are small enough that they aren't very noticeable. The mouse charges properly every single time I place it in the cradle now.

It feels like it was a million years ago that I was just playing around with btrfs. I am not playing around any longer: my primary workstation (also known as my laptop) has been running btrfs as its root file system for a little over a month now.

I haven't run any benchmarks... I don't want to know if it tests any slower than ext4. The machine feels pretty much exactly like it did before the switch and that is good enough for me. The only thing btrfs has been absolutely terrible at is storing QEMU/KVM disk images. That's a bit disappointing because copy on write snapshots and file clones of virtual machine disk images would be quite awesome, especially once deduplication hits btrfs.

How I Configured my Subvolumes

The first thing I did was store my / in its own subvolume. This makes changing your default root subvolume easier if you later decide you don't have a need for the original again (if something like an apt-get dist-upgrade goes awry). It also lets you keep the real default btrfs subvolume unmounted and out of the way.

I ended up with four subvolumes:

• / - The operating system and config files
• /home - All my local user home directories, there is only one user
• ~/wip - My "work in progress" directory. Most anything I am working on. I broke this one out because it is the volume I am most likely to manually snapshot
• ~/tmp - Junk. Garbage. Mostly I untar and compile things here. This one gets its own subvolume because it is likely to fill up with junk that I won't need. If I run low on space I can clobber old snapshots of this without even giving it much though.
• ~/Downloads - My default web browser download folder. Almost exactly like the ~/tmp directory.

This layout has mostly been working pretty well. I like that I can snapshot /home without accidentally storing copies of useless data in ~/tmp and ~/Downloads. I bet I have saved a few gigabytes by not snapshotting any Linux kernel compiles sitting in ~/tmp.

Unfortunately, I realized I would always like a snapshot of ~/wip with every snapshot of /home. It isn't a big deal in practice because it is simple enough to script.

The Verdict

I'm very happy with btrfs. The performance is great for me in all but one use case. I've been wanting proper read/write copy on write snapshots on my workstation every since the first time I read about zfs a few years ago. I'm so happy to finally have them!

I haven't yet noticed any corruption (I hope!). However, I am running backups way more often than I ever did. I only once lost data to a file system corruption once (reiserfs on my dual Intel Celeron 366). While running ext3 and ext4 I was really only worried about hardware failure. Now I am worried about hardware and software failure, which makes me quite a bit more nervous.

I have wanted to build an arcade cabinet for a very long time. I finally decided to stop thinking about doing it and actually do it!

Some of the Inspiration

I decided that I we are going to build a four player cocktail cabinet. We like the design of the Crazy Canadian's Custom Cocktail Cabinet. We might use nice looking stain grade wood but I really like the look of The NEON MAME cabinet with light blue T molding on a black cabinet.

Some of our Constraints

I think a cocktail cabinet will be more useful than an upright cabinet since it can also double as a table. I want this build to be lean towards being a table instead of just a cocktail cabinet. I don't want to have a box underneath, I want you to be able to pull a chair up to it and put your legs underneath. I also don't want the controls to stick out past the glass tabletop. I am also trying to keep the tabletop at about the usual height of a desk or table.

It turns out that this isn't going to be as easy as I thought at first. The joysticks are fairly deep and you need enough room between the control panel and the glass so that you can comfortably use the controls. Our joysticks drop about 3 inches below the top of the control panel and we think we need about 6 inches of clearance between the panel and the glass. Fudging in 1 inch for the glass tabletop and the covering under the panel that will put the bottom of the controls 10 inches below the table top.

My desk here is about 30 inches high. 10 inches would below that would have the controls just about sitting on my chair. We've been figuring the tabletop height will end up having to be somewhere around 34 inches (maybe 33 if we're lucky!). It is a little on the high side but shouldn't be ridiculously tall.

Our life size white board diagrams have the tabletop dimensions at about 37 by 29 inches using a 24 inch LCD panel. We've seen some deals on 36 inch square tabletop glass (for some reason square is significantly less expensive than a rectangle).

Control Panel Layout

We will definitely be using a 4 player layout. We thought about putting two players on one of the long sides of the cabinet. That would let me put the table up against a wall and it would be great for fighting games. We think it might be a little too crowded, though, so we will probably go with one player to a side.

What Games Do I Want to Support

The most important game this cabinet needs to support is Mortal Kombat II. I was in high school when Mortal Kombat and Mortal Kombat II were released and we used to play quite a bit.

The four player game I have in mind is Gauntlet), though I'm sure there will be others. There is no reason to limit the cabinet to arcade games. I was thinking Liquid War would be a good fit.

The Parts We Have So Far

I ordered joysticks, buttons, and connectors from Groovy Game Gear. I was hoping to use their GP-Wiz40. It looks like a good product and a good value (and an even better value if you don't mind soldering). Unfortunately, we need 44 inputs and that is four too many.

I ended up going with an I-PAC 4 from Ultimarc. It has more than enough inputs and didn't cost much more than a pair of GP-Wiz40 controllers.

I went with the HAPP™ Super Arcade Joystick. I am surprised how happy I am with them. They work very well as an 8 way joystick and they seem to make it pretty easy to perform circular style moves in Mortal Kombat.

I also got buttons for players one through four and six HAPP Black Horizontal Pushbuttons for each player.

The Mock Up Test Controller

We put some holes in a piece of wood and put together a test controller. It works great. The buttons feel right and the joystick feels great. We will definitely be doing with the two-rows-of-three-buttons layout but I am unsure what sort of spacing and staggering they will have. Yes, we indeed forgot to leave room for the Player 1 button...

The test controller has very arcade like wide button spacing. 2.0 inches between button centers on the vertical, 1.625 inches on the horizontal. It seems a little too wide, I will probably tighten that up for the final product.

Plopping the control panel down on my desk isn't ideal. Getting the half-circle moves to go off is a little hit or miss because the controller slides around. I don't think it will be a problem on the real controls that are bolted to the table.

How Long is this Build Going to Take?

Hopefully not too long! We've been talking about this and drawing on the white board for probably two months so far. Now that I have actually had a controller in my hands I am getting very excited.