Computable – iPython for the iPad

Now there’s a full featured iPython implementation for the iPad called Computable. It includes NumPy, SciPy, matplotlib and Pandas. It supports the creation of iPython notebooks that you can then share. This is a handy tool when a typical scientific calculator or spreadsheet just won’t cut it. Recommended.
icon
NB: Sadly, due to Apple’s restrictions on apps and executable code (including scripts) the app is not able to download or sync iPython notebooks. I understand and agree with the restriction from a security standpoint, but it does limit the usefulness of a tool like Computable.

World Championship Hoop Dance

Hoop Dancer (from Heard Museum)

Powwows.com has an article on the 24th annual world championship hoop dance competition, recently held at the Heard Museum in Phoenix, Arizona. The videos are amazing.

Back in the late ’70s and early ’80s when I was part of an Explorer Troop that focused on native american dance, one of the things I did was hoop dance. I learned how from a couple old books and a couple of dozen stills and diagrams. It would have been wonderful to have had videos to help me figure out the foot work and transitions

Internet with Frickin’ Lasers

MetroNet’s second commercial installation in the Lafayette area (or so the installer guys said) is in my basement. It’s very fast, especially to the Purdue campus. If you get MetroNet’s service in West Lafayette, you can add a symmetric 100 Mb/s service to campus to your connection for $10. Four router hops to systems on campus. Very nice.

You can find a good technical introduction to the fiber technology MetroNet is deploying in this presentation to the Greater Lafayette Information Technical Society from 2011.

Network termination board

Network Termination Board in my basement

The picture is of my network termination board next to the equipment rack in the basement. The MetroNet optical network terminal (ONT) is the big grey box in the middle of the picture. The little grey box to the upper right is the old DSL termination box which was retired when I moved to Comcast. The dark grey, almost black box above the ONT is the Comcast cable modem. Once the fiber gets buried in the yard, I’ll retire the Comcast connection.

So pretty…

One of my long term projects moves forward… New (to me) bustles. Slowly pulling together the missing pieces of a new fancy dance outfit. Now I really need to work on my beaded harness set and a couple of large, beaded rosettes…

20140130-225127.jpg

Replacing a harddisk in a Mac Mini Server

Behind the scenes, my household network services are provided by a pair of Apple Mac Mini Servers, one for internal services (DNS, DHCP, file sharing, backups) and one for external services (DNS, mail, web hosting, ownCloud). I also have an older Mac Mini attached to my home theatre. I like the Mac Mini’s a lot. They are inexpensive as servers go, draw little power, and are quiet, cheap and reliable.

Apple Mac Mini Server

Apple Mac Mini Server

Sadly, the internal server’s boot disk died a couple of weeks ago. It failed slowly over a couple of hours and thankfully did not corrupt the server’s time machine based backups on its way out. I have prepared for this eventuality by keeping a cold spare  in the form of an older Mac Mini that sits on the shelf, ready to be put into service if one of the active Mac Minis has a problem. So, after an attempt to resuscitate the dying hard disk, I gave up on it and restored the most recent backup of the server onto the cold spare.

The restore process is pretty simple. First, I choose to boot the cold spare from a USB key that I had prepared with a bootable installation image of OS X Mavericks. I used the included script that’s buried in the Maverick install image to create the bootable USB key. The directions for using it can be found from Apple or with a bit more detail from MacWorld. You will need to have either saved, or downloaded the current Mavericks installer before you follow those instructions.

Once the USB key and cold spare are ready to boot, I booted with the “option” key held down and picked the prepared USB key from the list of available boot devices. When restoring a server with more than one disk, you need to do a little bit of extra work to restore the second disk before you start the restoration of the boot disk as detailed in this Apple Knowledge Base article. After restoration, the cold spare booted up without problems. I corrected it’s network settings (it has a USB ethernet connection, long story for another post…), checked that services were running, “inherited” the current time machine backups and my internal services were back in operation.

Next up, I ordered up an SSD to replace the failed disk. SSDs have come a long way in terms of reliability and are well worth the added expense given the marked speed improvement they offer. I chose a Samsung 750GB EVO 840 drive based on the recommendation of the good folks at Mac Mini Colo. I bought the drive from OWC and followed their installation video. The install is indeed “challenging” and took me about 90 minutes.

Mac Mini Disassembled

My Mac Mini disassembled

A word of warning, I ended up doing the disk installation twice due to pulling the wrong drive the first time. If you can, before you remove the dead disk, look at the system with disk utility which will indicate which drive bay (upper or lower) a disk is located in. That would have saved me some time.

The server with the SSD has been running for a few days now without problem and I plan to swap it back into production service, using the same time machine restoration process, this weekend.

Start the Year by Enriching Your Marriage

Mary and I will be teaching a marriage study we call, “A Lasting Promise”, at Calvary Baptist Church starting next Sunday, January 12th at 6pm. The study runs 9 weeks.

A Lasting Promise Book Cover

A Lasting Promise

The study is based on PREP (Prevention and Relationship Enhancement Program) developed by Howard Markman, Ph.D and Scott Stanley, Ph.D. We named the study after one of Markman and Stanley’s books. Combining biblical truths and tested research, the study offers practical coaching on relationship skills that lower the risk of divorce, strengthen commitment and restore fun, friendship and intimacy.

The study is open to all couples at a cost of $20 for materials. Childcare is available for $2 per child or a maximum of $5 per family.

You can sign up here, or contact us via email.

You can download and print a handy reminder card for yourself or other folks you know here.

We hope to see you next Sunday!

Coin: Tempting but problematic

Wouldn’t it be great to carry just one credit card that could replace all the cards in your wallet?

Well this new digital credit card device called coin might make that possible. The video on their site shows you how this works. In brief, you swipe your card through a reader attached to your iPhone, the data is transferred to the device by bluetooth low energy and then the device can set its magnetic strip to mimic any card you’ve loaded into it. Yes, that’s right, you select a “card” on the coin display and then swipe the coin device just like a credit card.

While this sounds great, it looks to me like it has numerous problems. Here are the first few that come to mind.

The first one is acceptance. While asking the cashier of a shop in San Francisco to swipe a device instead of a card might work, I’m doubtful an hourly worker at restaurant here in the Mid-West is going to go for it. It does’t look like a real credit card and won’t pass the typical visual inspection a cashier does on a card. There’s no signature. The expiry and security code are on the display. I would imagine getting rejected more often than not.

The second one is that I believe that use of this device is beyond the limits the credit card companies put on how the card data can be used and stored. The Coin folks say in their FAQ that they are pursuing PCI DSS Certification, which will be critical. Failing to be certified to hold and transmit credit card data could result in a directive from the credit card companies to shops to not accept transactions from this device. Also, it might influence what the credit card companies are willing to do in the event of fraud.

The brings up the third issue, fraud. While I already feel a little uncomfortable giving my card to wait staff who walk off to ring up by bill, giving them this device gives them access to several cards. Coin’s answer to this concern is a proximity based lockout that engages when the device is away from your phone. Could the device be hacked and the data easily downloaded? Can a waiter switch cards, either on purpose or on accident? How about other uses? Can you swipe hotel room key cards and store them in the device? That could cause some interesting problems…

And yet… It sure is cool. I would use one if the problems with it were less.