Archive for category Hardware

DROID X micro SD card speed test

Okay, so I know there must be 1k sites out there with this info already but I felt like finding out for myself.

Out of curiosity I wanted to know how fast manufacturer provided the micro SD card in my DROID X phone is. Today I did a test to figure that out.


  1. Copy contents of sd card to computer
  2. Reformat SD card using phone. For Droid X, go into settings -> SD card … -> Unmount -> Format
  3. Connect phone to PC in USB Mass Storage mode
  4. Download ATTO disk benchmark tool:
  5. Select the correct drive and test.
  6. Copy data back to phone (from step 1)


You can see that the write speed peaked at about 7.5MB/s and read peaked at just over 13MB/s. These speeds qualify this card as a class 6 card. Not bad considering the card is labeled as class 2. I expected far worse. So, if you are planning to replace this card and want one with at least the same performance buy class 6 or higher. Numerous forum users are reporting that cards higher than class 4 cause problems on the Droid X. I tried a class 10 and had to return it. Now I am using a class 4 with no problems.

First good real world use of RFID

So I was at Six Flags Hurricane Harbor a couple weeks ago and found what I believe is the first decent real world application of RFID. Maybe that’s a slight exaggeration but I like this application.

RFID Crash Course… Skip me if you know what RFID is.

RFID of course stands for radio frequency identification. RFID tags are small transponders (usually passive) that harvest energy from a received radio signal to in turn transmit their own response. This allows the tag to be extremely small and lightweight because it does not need a battery to function. The response sent by every tag can be tweaked so that each tag has its own ID number. The ID number serves as input to a computer system and the computer can perform processing based upon that ID number.

If you’re still confused try taking a look at the wikipedia article.

The Hurricane Harbor setup

This year Hurricane Harbor installed a new set of lockers throughout the whole park. These lockers are for rent for a day ($10-$16). The goal of course is that you can store sunscreen and such in the locker and come back periodically. Previously park customers received a physical key when they paid for a locker. Of course, Hurricane Harbor wants their key back so they also required a deposit from you that they would refund if you return the key. These keys were a pain and I’m sure many got lost.

This year Hurricane Harbor’s lockers use RFID bracelets instead of keys. In the lower two pictures you see our bracelet. The underside shows the circuit that comprises the RFID tag. These are light, thin, waterproof and flexible so they are of little discomfort to the wearer. Best of all each of these bracelets is cheap so Hurricane Harbor doesn’t want them back! No more locker deposit.

RFID bracelet top

RFID bracelet top

RFID bracelet bottom

RFID bracelet bottom

The System

The system flowed pretty smoothly from a consumer point of view. The biggest hassle was a 10 minute line to pay and receive a bracelet at the beginning of the day. The bracelet giving process itself is quick but everybody paying with credit cards is slow. So when you pay you are given a bracelet of color that represents which lockers you can use. Each color corresponds to a size of locker. Once you have the bracelet they instruct you to go to the lockers and follow the instructions there.

At the lockers we found an electronic screen and an emblem that says “hold bracelet here”, The screen read something to the effect of “scan bracelet” or “All full”. All full of course means go look for another set of lockers if you haven’t already received one. In order to receive your locker for the day you just look for a unit that doesn’t say “all full” and then you swipe your bracelet. After a moment the screen displays a message to say “Your locker is … xyz”. And if you look at locker number XYZ its door just flung open. How cool!

So anytime you want to return to your locker you just go to the screen for your unit and swipe you bracelet at the reader. Then your locker door will fling open.

And what kind of person would I be if I didn’t give you a link to the datasheet?


Me being a geek I really liked this system. I felt like it was a good use for the technology. And before someone points out that I’m ignoring car “toll tag” and “ez pass” systems I’ll tell you why this is different. The car/toll systems use a much larger unit meant for scanning from much larger ranges. This was indeed a great use for RFID. However, the passive, thin, light and cheap variety of RFID has been the source of many empty promises to consumers about how this technology can change their lives. I’m excited to see the locker application pop up because it is a fufulled promise. Thank you SmarteCarte and Six Flags Hurricane Harbor.

Ooops. I just thought of another good succesful application of this type of RFID. Pet “microchips” to identify lost pets. I like that application too. I had my dog microchipped when she was a pup.

PowerEdge 6650 NIC Issues


I have a new problem with my Dell PowerEdge 6650 servers. They crash! Well sort of. Under heavy NFS usage (usually compiling a large program over NFS mount) the machine seems to hang. I use the word seems because all SSH connections to the machine timeout and it does not respond to network traffic. However, a look at the console proves the machine is alive and well.


  • 2x Dell PowerEdge 6650 Servers (One NFS client, One NFS server)
  • Embedded Broadcom BCM5700 Gigabit NICs (Connected via Cisco Gigabit switch)
  • CentOS 5.2 custom kernel 2.6.25


Once on the console the obvious act is to check the system logs. If you wait long enough, the network interface begins working again and the following messages are in the system log. Of course eth1 may be replaced by your interface.

kernel: NETDEV WATCHDOG: eth1: transmit timed out
kernel: tg3: eth1: transmit timed out, resetting
kernel: tg3: DEBUG: MAC_TX_STATUS[00000008]  MAC_RX_STATUS[00000008]
kernel: tg3: DEBUG: RDMAC_STATUS[00000000]  WDMAC_STATUS[00000000]
kernel: tg3: tg3_stop_block timed out,  ofs=1800 enable_bit=2
kernel: tg3: tg3_stop_block timed out,  ofs=4800 enable_bit=2
kernel: tg3: eth1: Link is down.

This says that the ethernet watchdog figured out that the network interface hung or crashed or deadlocked or got stuck. The remedy? The watchdog restarts the interface.

So everytime you get the network crash you have two options….

  1. Wait ~15 minutes for it to fix itself (miraculous, I know!)
  2. Restart the networking service

Resolution 1

As I mentioned this was fairly repeatable for me. All I had to do was attempt to compile an application in a remote directory mounted with NFS. The NFS client was always the party to crash. The cheap (well lazy) fix that I took was to add a spare PCI gigabit NIC to the client machine. This resolved the problem on the client side.

Problem Re-emergence

After a couple weeks of operating with the client on PCI NIC and server on embedded NIC, the server’s NIC locked up just like the client’s had previously. This time I got a little fed up because I didn’t have a spare gigabit NIC to put in the server.

Resolution 2 – I Hope

This resolution is tentative. I have implemented it and have not had a crash but I do not trust that it is permanently fixed until more time has passed. I’ll post an update if I have any new issues.

At the advice of the local sysadmin I went to Dell’s website and poked around until I found an ISO cd image that contained all of the possible firmware updates for the PowerEdge 6650 on one CD. He recommended I give that a try and upgrade every single piece of firmware possible.

The result of the scan from the CD was that I was up to date on everything but “BMC” the Board Management Controller. My version was 1.64 and the latest was 1.78. So I let the CD do the firmware upgrade for me.

Since the upgrade (28 days ago) and a reboot I have not had another NIC crash. I don’t consider this conclusive yet because it is very possible that the situation has to be just right.

In summary the correct solution appears to be to update all of the server firmware (duh?). The easiest way to do that is to get the update CD for your OS from Dell. The CD is called something like “Dell CD ISO – PowerEdge Updates”. Let this also be a warning. Until I knew that update CD existed, I thought that I had upgraded all of the firmware possible in the server via individual floppies. Don’t make the same mistake, try Dell’s update all CD.

Failure .. Again!

Today I have crashed the NIC in the NFS server again… I’m looking for a new fix!

See Comments for updates from me.