From experience, it takes 2.5 hours to recharge Sony wireless headphones (MDR-XB70BT) from empty to full. This is also stated in the manual. The Sonys give 9 hours of battery life for listening. At 3 hours per day of usage, that’s 3 days between charges.
It takes 1.25 hours to recharge the Apple AirPods battery case. They give 24 hours of battery life when new. At 3 hours of usage per day, that’s 8 days between charges of the battery case.
Like all battery-driven headphones, you need to charge more often as the battery ages. After ~1 year of usage, I’ve found I need to recharge the AirPods battery case every 4 days, instead of every 8.
As an aside, I got the AirPods with wireless charging case, and don’t really like the wireless aspect of it. It’s too hard to position the AirPods perfectly on most wireless chargers. Next time, I’ll get the non-wireless AirPods.
My colleagues and I had trouble AirDropping files from our Macs to our phones. Sometimes it worked, sometimes it didn’t.
I figured out that AirDrop would fail with the Cisco AnyConnect VPN client connected.
Specifically, when your Mac’s sharingd service tries to connect to https://yourphone.local:8770/Ask to ask for permission to accept a file, it times out via the VPN. This happens even if LocalLanAccess is allowed in your VPN settings.
The solution was simply to disconnect the VPN client whenever you need to AirDrop something.
I had a problem for months in Apple Mail (both on the Mac and the iPhone) where multiple folders would show up with an Unread mail count, even if all mail in that folder was already read. If you clicked one of the Unread folders, the Unread count would instantly go away. (But it would reappear when re-opening Mail.)
Here’s how I fixed it:
Open Mail on the Mac
Click on the Archive (or All Mail) folder
Select all mail, right-click on the selected mail, and hit Mark as Unread
Repeat step 3, but now hit Mark as Read
Now close and open Mail again and you will no longer see folders with Unread mail in them. If the problem continues to occur, you may need to repeat steps 2-4 on all of your mail folders.
I recently received an Eve Room HomeKit Air Quality monitor. But when I plugged it in, nothing happened. I let it charge overnight, and it remained stuck on the charging screen. I reset it with a paperclip multiple times. Tried multiple chargers. Tried a different micro-USB cable. All to no effect. The battery either seemed completely discharged upon arrival, or something was broken inside the unit.
That’s when I emailed Eve Support. They suggested resetting it again and waiting a few hours. I did, to no avail. After I sent them a photo of the non-working unit, they agreed to a quick, free replacement.
And the replacement worked great!
My experience with Volker and Sarah at Eve Support couldn’t have been better. Polite, prompt, professional, and a free replacement. I liked their service so much that I went out and bought a second Eve Room for the lower level of my house. I’m also planning to get one as a gift for a family member.
History graphs of your data (see below) – including exporting history to spreadsheets
HomeKit support – You can ask Siri to tell you the temperature/humidity/air quality in any given room
Automation – In the Home app, you can have an air purifier come on automatically when air quality drops
More automation – In the Eve app, you can add additional automations based on temperature and humidity. For example, when temp/humidity get above 80F (26.6C), turn on air conditioner.
What are some downsides?
Bluetooth-based, which means it takes slightly longer (~1 second) than WiFi-based HomeKit products to display status in the Home app.
If you want to access Eve from outside your house, you need a HomeKit hub, such as an Apple TV, HomePod, or iPad. (In my experience, the Apple TV is the most reliable of the three.)
Expensive – $70 more than the bigger AcuRite monitor (though it’s tough to find an air quality monitor with a display for less than $70).
Not magnetized like the AcuRite – so you can’t stick it to your refrigerator without adding a magnet.
Charging is easy. It takes less than 2 hours and only needs to be done once every couple months. You can also use it with the charger plugged in, though it’s possible this will reduce the battery lifespan a bit. With the AcuRite, you need to replace the 2x AAA batteries every other year. (Though my first AcuRite started reporting obviously incorrect temperatures after a few years – I just bought another one since it was so cheap.)
Are the air quality measurements any good? The only thing I have to compare it to are the measurements from my Withings scale downstairs. The Withings reacts pretty fast to cooking in the kitchen. The Eve Room seems to be a bit more … optimistic on air quality, even when the air seems a bit stale. (a quick blast of the air conditioner clears this up though) It doesn’t care much about soiled diapers, but it does react when people are in the room breathing out carbon dioxide for half an hour or so.
Overall, fun little gadget, and I’m looking forward to setting up automations with it!
I have a small Dell E310DW laser printer, which is a rebranded Brother L2340DW wireless printer. Bought it for $90 three years ago. Today, I discovered the printer’s internal status page. Here’s how to get to it:
With the printer on, go to http://dell5bbcd8.local./general/information.html?kind=item (this address may be slightly different depending on whether you have a Brother or Dell printer). Not sure if part of the address is randomized though. If it doesn’t work, try putting your printer’s IP address in your web browser’s location bar.
You’ll see a page that looks similar to the one below. You can go to the home page to see the amount of toner remaining.
After I bought this printer, I sold my old non-wireless HP LaserJet P1006 printer for $40 on Craigslist. Even though it needed toner, I still had 4 people competing to buy it.
A few more things I love about this Dell/Brother laser:
Fast duplex printing (prints on both sides of the page to save paper)
Works wirelessly with no software to install on Macs, iPads, and iPhones
You can continue printing even beyond the toner’s estimated print life by enabling “Continue Mode“. Use the printer controls on the printer itself, or log into the printer web management (described above), and set the replace toner option to enable this mode.
After 3 years, I’ve printed 265 pages. That’s 88 pages a year, or 7 pages a month. I have roughly 60% of my “starter toner” remaining. At this rate, I’ll be be able to use the original toner for at least another 3-4 years! This would be unheard of in the inkjet world.
DNS caches are checked: browser cache, operating system cache
Local computer’s hosts file and the router’s cache are checked
Local computer’s resolver config is checked for the address of the recursive DNS server (ex. ISP’s DNS server). That server’s cache and records are then checked for example.com, usually via UDP port 53.
Root DNS servers for .com are checked
Top Level DNS servers are checked
Authoritative DNS servers are checked
If the record is found, the result is cached by the recursive DNS servers and your local system
Browser sends HTTP request to the IP returned by the DNS server:
Makes system call to the operating system’s kernel to create a TCP internet socket (fd = socket(AF_INET, SOCK_STREAM)
Connects to a port (ex. 80) on an IP (from DNS) (fd, 188.8.131.52:80)
Makes a request (write (fd, "GET /index.html HTTP/1.1)
Reads the response (index.file=read(fd ...))
Server responds and sends back the requested HTML file
Browser renders HTML
I used the following resources in researching this:
I was recently asked how to troubleshoot layers 4-7 of the OSI model.
Layer 4 (Transport) : Most problems at the transport layer have to do with blocked ports. Ensure there are no firewalls (ex. iptables) blocking the TCP/UDP ports you’re trying to troubleshoot. You can also try temporarily disabling quality of service (QoS).
Layer 5 (Session) and Layer 6 (Presentation) : Example protocols in these layers include sockets in the session layer and MIME in the presentation layer. These two layers play a less active role in the functioning of the network compared to the other layers of the OSI model. There usually isn’t anything here to troubleshoot.
Layer 7 (Application) : The app layer is where client-server apps are used. For example, HTTP, HTTPS, SMTP, SSH, DNS. Regarding DNS, use the dig or nslookup commands as a starting point to figuring out why DNS is failing. For HTTP, you might use Apache’s or NGINX’s stats pages. (Be sure to turn these off when you’re done using them though, for security.) For SSH, SMTP, and all cases: check the logs. Temporarily enable debug logging if you have to. You can also use tcpdump to filter TCP/IP packets and analyze the protocols used.
There is certainly more that could be said here, but I just wanted to write down what I’ve learned so far. Credit for much of the above info goes to:
I was asked about vmstat recently and didn’t know as much as I should. I’m writing a brief post to help myself learn it a little more.
Here’s an excerpt of the manual:
So what can you do with vmstat? If you run it without specifying any parameters, it gives you an average view of virtual memory and system usage since your last reboot.
If you run it with the 1 parameter (vmstat 1), it runs (and re-measures) every 1 second, until you break out of it:
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
r b swpd free buff cache si so bi bo in cs us sy id wa st
3 0 0 44712 110052 623096 0 0 30 28 217 888 13 3 83 1 0
0 0 0 44408 110052 623096 0 0 0 0 88 1446 31 4 65 0 0
0 0 0 44524 110052 623096 0 0 0 0 84 872 11 2 87 0 0
If you want to see how much memory is swapped in/out from disk, check out the si/so (swapped in/swapped out) columns.
If the amount of memory in the free column is low, you’ll want to check which processes are consuming the most memory. (with top, for example)
But wait – you can also troubleshoot CPU and disk bottlenecks with vmstat:
For disk bottlenecks, look at the b (blocked) column. This tells you the number of threads that were blocked/waiting on IO completion. It should be 0 most of the time, but if it’s not, you can investigate further with iostat.
For CPU bottlenecks, look at the r (run queue) column. These are the threads that were waiting for a CPU to become available in order to run. If you see more than 2-5 times the number of CPUs on the system listed in this column, there may be a CPU bottleneck.