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Fun with WSL (Ubuntu on Windows)

Tuesday 15 of August, 2017

I'm running WIndows 10 1703 and have been toying with the Windows Subsystem for Linux (WSL). THis version is based on Ubuntu.  There is some fun it making it useful.  

SSH into WSL

I want to use putty from anywhere to access the shell. SSH requires a few things to make it useful.  Start the bash shell and edit /etc/ssh/sshd_config (sudo nano /etc/ssh/sshd_config)

  • Change the listener.
    • port 2222

  • Turn on Password Authentication (I'll discuss key auth in a bit)

  • Turn off Privilege separation. Rumor has it it isn't implemented

  • Allow TCP port 2222 in the Windows Firewall

  • Generate host key
    • sudo ssh-keygen -A

  • Restart ssh service
    • sudo service ssh --full-restart

You should be able to ssh into the host.






Using Powershell to post data to IFTTT WebHooks service

Monday 07 of August, 2017

IFTTT has many useful triggers and I like Webhooks because it can enable so many fun interactions.  My goal today is sending JSON key:value pairs to WebHooks from Powershell (my preferred scripting language and now available on Linux!).  

WebHooks will accept three named parameters vis JSON (also form data and url parameters) that can be referenced within the Action of your applet.  The paramaeters are named value1, 2 & 3. so the JSON should look like this: 

    "value1":  "Good Morning",
    "value3":  "That is all.",
    "value2":  "Greg"

PowerShell has two methods for posting this to a URL Invoke-WebRequest and Invoke-Restmethod.  The latter is apparently a wrapper of the former and return onthe the string output from the POST. Because of the possible error-checking needs, I'll focus on Invoke-WebRequest.  

Here is the code that made this work:

$BaseURL = "https://maker.ifttt.com/trigger/GMhit/with/key/enteryourkeyhere"

  1. Note: The key (last part of URL is user unique

  2. The Trigger here is GMhit and unique to me. You would declare your own in the IFTTT service

$body = @{ value1="Good Morning" value2="Greg" value3="That is all." }

  1. Either works. Webrequest return status code

  2. Invoke-RestMethod -URI $BaseURL -Body (ConvertTo-Json $body) -Method Post -ContentType application/json

Invoke-WebRequest -URI $BaseURL -Body (ConvertTo-Json $body) -Method Post -ContentType application/json


  • Setting the ContentType to `application/json` is important here.  This call didn't work until this was set correctly.

  • The value names are fixed and cannot be customized.

Recovering from a Bad Drive in a Greyhole storage pool

Monday 13 of February, 2017

I run an Amahi home server which hosts a number of web apps (inlcuding this blog) as well a a large pool of storage for my home.  Amahi uses greyhole (see here and here) to pool disparate disks into a single storage pool. Samba shares are then be added to the pool and greyhole handles distributing data across the pool to use up free space in a controlled manner.  Share data can be made redundant by choosing to make 1, 2 or max copies of the data (where max means a copy on every disk).

The benefit over, say, RAID 5 is that 1) different size disks may be used; 2) each disk has its own complete file system which does not depend on disk grouping; 3) each file system is mounted (and can be unmounted) separately or on a different machine.

So right before the holidays, the 3TB disk on my server (paired with a 1 TB disk) started to go bad.  Reads were succeeeding but took a long time.  Eventually we could no longer watch video files we store on the server and watch through WDTV.  Here is how I went about recovering service and the data (including the mistakes I made).

  • Bought a new 3TB drive and formatted it with ext4 and mounted it (using an external drive dock) and added it to the pool as Drive6.

  • Told greyhole the old disk was going away (drive4)
    greyhole --going=/var/hda/files/drives/drive4/gh

    Greyhole will look to copy any data off the drive that is not copied elsewhere in the pool. It has no effect on the data on the `going` disk (nothing is deleted) except it could cause further damage. The command ran for several days and due to disk errors didn't accomplish much, so I killed the process and took a new tact.

I decided to remove the disk from the pool and attempt an alternate method for recovering the data. 

  • Told greyhole the drive was gone.
    greyhole --gone=/var/hda/files/drives/drive4/gh 
    Greyhole will no longer look for the disk or the data on it.  It has no effect on the data on disk. 

  • Used safecopy to make a drive image of the old disk to a file on the new disk. (if you not used safecopy, check it out.  It will run different levels of data extraction, can be stopped and restarted using the same command and will resume where it left off.
    safecopy --stage1 /dev/sdd1 /var/hda/files/drives/Drive6/d1 -I /dev/null

This took about two weeks to accomplish due to drive errors.  And because I was making a disk image, I eventually ran out of space on the new disk before it completed.

  • Bought a  4TB drive and mounted it using an external dock as drive7; copied over and deleted the drive image from the Drive6.

  • Marked the 1TB drive (drive5) as going (see command above) and gone. This moved any good data off the 1TB drive to drive7 but left plenty of room to complete the drive image.

  • Swapped drive5 (1TB) and drive7 (4TB) in the server chassis. Retired the 1TB drive.

  • Mounted the bad 3TB drive in the external dock and resumed the safecopy using:
    safecopy --stage1 /dev/sdd1 /var/hda/files/drives/Drive7/d1 -I /dev/null

  • Mounted the drive image. The base OS for the server is Fedora 23. The drive tool inlcudes a menu item to mount a drive image.  It worked pretty simply to mount the image at /run/media/username/someGUID.

  • Used rsync to copy the data form the image to the data share.  I use a service script called mount_shares_locally as the preferred method for putting data into greyhole pool is by copying it to the samba share.  The one caveat here is that greyhole must stage the data while it copies it to the permanent location. That staging area is on the / partition under /var/hda.  I have about 300GB free on that partition so I had to monitor the copy and kill the rsync every couple hours. Fortunately, rsync handles this gracefully which is why I chose it over a straight copy.

rsync -av "/run/media/user/5685259e-b425-477b-9055-626364ac095e/gh/Video"  "/mnt/samba/"


A couple observations.  First, because of the way I had greyhole shares setup, I had safe copies of the critical data. All my docs, photos and music had a safe second copy. The data on the failed disk was disposable.  I undertook the whole process because I wanted to see if it would work and whatever I recovered would only be a plus.  

This took some time and a bit of finesse on my part to get the data back.  But I like how well greyhole performed and how having the independent filesystems gave me the option to recover data on my time. Finding safecopy simplified this a lot and added a new weapon to my recovery toolkit!.



Reset a Whirlpool Duet washer

Monday 06 of April, 2015
We accidentally started the washer with hot water feed turned off. When the washer tried to fill, it couldn't and generated F08 E01 error codes. After clearing the codes and restarting, we eventually got to a point where the panel wouldn't light up at all. Unplugging and re-plugging the power would do nothing except start the pump.
It was obvious it needed to be cleared. After too much searching, I found this link on forum.appliancepartspros.com (cache).

It tells you to press "Wash Temp", "Spin", "Soil" three times in a row to reset the washer. Once it resets, the original error will display. Press power once to clear it. After that - all was well (of course I turned on the water first)

Adjusting Brewing Water

Tuesday 10 of March, 2015
I recently got hold of (well, asked for and received) a water analysis from the Perkasie Borough Authority and have been staring at it for more than a month wondering what to do with it. I've read the section on water in Palmer's How To Brew and some of his Water book. These are both excellent resources and while I have a science background, they are quite technical and I've been unable to turn all the details into an action to take, if any, on my brewing water.

The March 2015 issue of Zymurgy (cache) has an article by Martin Brungard on Calcium and Magnesium that has helped me turn knowledge into action. At the risk of oversimplyfying the guidance, I want to draw some conclusions for my use.

Some of Martin's conclusions
  • A level of 50mg/L Calcium is a nice minimum for many beer styles
  • You may want less than 50mg/L for lagers (wish I knew that a week ago) but not lower than 20
  • A range of 10-20mg/L Magnesium is a safe bet for most beers
  • Yeast starters need magnesat the high end pf that range to facilitate yeast growth

The Water Authority rep who gave me the report said two wells feed water to our part of the borough. Looking at the two wells, the Ca and Mg values are similar averaging 85 mg/L and 25mg/L respectively.

This leaves my water right in the sweet spot for average beers styles. What about some of the edge cases like IPAs and lagers.

  • For lagers, next time I'll dilute the mash water with 50% reverse osmosis (RO) water to reduce the Ca to about 40. I may want to supplement the Mg to bring it back to 20.
  • For IPAs, I may want to add Mg to bring it up near 40 mg/L.

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Created by gmartin. Last Modification: Tuesday 27 of December, 2016 17:16:22 EST by gmartin.