Marc's Public Blog


All | Aquariums | Arduino | Btrfs | Cars | Cats | Clubbing | Computers | Dining | Diving | Electronics | Exercising | Festivals | Flying | Halloween | Hiking | Linux | Linuxha | Monuments | Museums | Outings | Public | Rc | Sciencemuseums | Solar | Tfsf | Trips




More pages: March 2024 February 2024 January 2024 December 2023 November 2023 October 2023 September 2023 August 2023 July 2023 June 2023 May 2023 April 2023 March 2023 February 2023 January 2023 December 2022 November 2022 October 2022 September 2022 August 2022 July 2022 June 2022 May 2022 April 2022 March 2022 February 2022 January 2022 December 2021 November 2021 October 2021 September 2021 August 2021 July 2021 June 2021 May 2021 April 2021 March 2021 February 2021 January 2021 December 2020 November 2020 October 2020 September 2020 August 2020 July 2020 June 2020 May 2020 April 2020 March 2020 February 2020 January 2020 December 2019 November 2019 October 2019 September 2019 August 2019 July 2019 June 2019 May 2019 April 2019 March 2019 February 2019 January 2019 December 2018 November 2018 October 2018 September 2018 August 2018 July 2018 June 2018 May 2018 April 2018 March 2018 February 2018 January 2018 December 2017 November 2017 October 2017 September 2017 August 2017 July 2017 June 2017 May 2017 April 2017 March 2017 February 2017 January 2017 December 2016 November 2016 October 2016 September 2016 August 2016 July 2016 June 2016 May 2016 April 2016 March 2016 February 2016 January 2016 December 2015 November 2015 October 2015 September 2015 August 2015 July 2015 June 2015 May 2015 April 2015 March 2015 February 2015 January 2015 December 2014 November 2014 October 2014 September 2014 August 2014 July 2014 June 2014 May 2014 April 2014 March 2014 February 2014 January 2014 December 2013 November 2013 October 2013 September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 February 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 November 2008 October 2008 September 2008 August 2008 July 2008 June 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 2006 May 2006 April 2006 March 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004 November 2004 October 2004 September 2004 August 2004 July 2004 June 2004 May 2004 April 2004 March 2004 February 2004 January 2004 October 2003 August 2003 July 2003 May 2003 April 2003 March 2003 January 2003 November 2002 October 2002 July 2002 May 2002 April 2002 March 2002 February 2002 November 2001 October 2001 September 2001 August 2001 July 2001 June 2001 May 2001 April 2001 March 2001 February 2001 January 2001 December 2000 November 2000 October 2000 September 2000 August 2000 July 2000 June 2000 April 1999 March 1999 September 1997 August 1997 July 1996 September 1993 July 1991 December 1988 December 1985 January 1980



2014/04/30 3rd Supercar Drive with Club Sportiva, Long Drive
π 2014-04-30 01:01 in Cars, Ncars
The last 2 times I did this, I had a great time, but like the other participants, it was difficult to appreciate the cars on the same footing and compare them when you drove them on totally different pieces of road. However, Ruch nicely agreed to do a long drive for us where we drove all 6 cars on the fun and twisty portion of the route.
This made the whole drive a bit over twice as long (and of course raised the price which is fair), and it was sooo worth it.

I think the only minus we had was being tired at the end of the day. If that's the worst that happened, it was a great day :)


drivers meeting
drivers meeting


And here are the cars I drove in sequence:

  • Lotus Elise
  • Ok, I had driven the lotus the 2 other times already, it's not a bad car, but just not my favourite. I think my worry is that if there is a patch of water around a turn, or something unexpected, the car has no means to help you (stability control). That's fine on a track where you control the environment and can't hit a tree or a bike, but on the road, I'm not a fan.




  • I then switched to the Aston Martin. It's a great touring car, but it's obviously not super nimble when thrown in turns, and what's up with the RPM gauge turning backwards?



  • The F430 was nothing new for me, but I still loved it. The sound is great, and it did great with braking and turns:

  • After 3 cars, it as time for lunch and a bit of rest :)


    And I was up for the Mercedes SLS. I expected it to be a heavy pig with a lot of grunt, but I was pleasantly surprised. It actually felt as nimble as the F430, and had more power. I actually liked it quite a bit:






  • Next, I got to try the Viper. Shifting on it is a workaround, and it scares me a bit because it has a lot of power and I don't trust the car to do much or anything to keep me on the road. The torque and grunt were just amazing, and so was the noise. It will put a smile on you while taking you to your death :)




  • And I finished with the 2013 GTR. It's definitely fast, does well around turns, and basically works no matter how badly you drive it :) It sure goes fast, but that kind of feels like cheating a bit..



  • While last year I was a bit disppointed by the shorter loop compared to my first time, this drive was awesome. We were all beat by the end of the day, and we got a real chance to try each car on an equal footing. It was well worth the time and money. Thanks Ruch for setting up this special drive for us.

    2014/04/28 Farewell To Our Cat
    π 2014-04-28 01:01 in Cats
    Unfortunately Jennifer has become more and more allergic to our cat in a way that it wasn't a good idea to keep him. On some days she'd be ok, on others not at all. At the same time the poor bugger has been needing more medical help, which I've been happy to give, and we figured we could likely keep him until his death, but recent flare ups Jennifer had made us decide otherwise.
    Because he was sick, it was not possible to give him away anywhere, but the nice lady I got him from over 10 years ago was able to get him back and will be able to care for him on his last days (including daily fluid shots, and more).

    Soon before he left, we when didn't know how much he'd live still, Jennifer wanted to give him a little tour of our yard with a made up leach. He wanted to go there, but due to racoons, poison oak he could bring home, and more, that just wasn't practical for him or us, so she gave him a supervised walk for him to enjoy the plants and grass:



    On his last day with us, I took a couple of pictures. By then he had lost a fair amount of weight already:



    After that, we had to do a full and thorough house cleaning:


    We'll miss him, he really was a good cat without an attitude and wanting nothing more than companionship, being pet, and sitting on your lap or next to you.





    See more images for Farewell To Our Cat
    2014/04/27 Cupertino Cherry Blossom Festival
    π 2014-04-27 01:01 in Outings
    After going last year, we went back this year both because it was fun, and to practise for our new upcoming trip to Japan :)

    Plenty of flower art:






    And other things:









    See more images for Cupertino Cherry Blossom Festival
    2014/04/27 Btrfs Multi Device Dmcrypt
    π 2014-04-27 01:01 in Btrfs, Linux

    How to manage a btrfs filesystem made out of multiple dmcrypt'ed drives

    If you are using raid0, raid1, raid10, raid5, or raid6 with btrfs and you want your filesystem to be encrypted, you need to encrypt each device seperately but later you'll want a script to decrypt all those devices.
    This can be done with /etc/crypttab, but I don't personally use it for arrays that I turn off to save power. You can use keyscript= in there to feed a script that will provide the decryption key, but I wrote my own script to tun the disks on, locate them by disk ID, decrypt them, and mount the resulting partition.

    If you are planning on using Raid5 or Raid6, you'll also want to read this page.

    For the mount to work, you of course have to create the crypted device and filesystem first. Here is a recommended way:

    cryptsetup luksFormat -s 256 -c aes-xts-plain64  /dev/sda4
    cryptsetup luksFormat -s 256 -c aes-xts-plain64  /dev/sdb4
    cryptsetup luksFormat -s 256 -c aes-xts-plain64  /dev/sdc4
    

    cryptsetup luksOpen /dev/sda4 sda4_crypt cryptsetup luksOpen /dev/sdab sdb4_crypt cryptsetup luksOpen /dev/sdac sdc4_crypt

    mkfs.btrfs -d raid0 -m raid0 -L btrfs_pool /dev/mapper/sd[abc]4_crypt

    After reboot, the idea is to avoid the luksOpen steps and adapt to whatever device names those drives could come up under, and this is what the script below does.

    Here is the script, start-btrfs-dmcrypt, for which I'll paste a most likely outdated copy here:

    #!/bin/bash
    

    # Example script to decrypt a bunch of drives and then mount them as # part of a btrfs volume. # # By Marc MERLIN <marc_soft@merlins.org> / 2014/04/29 # License: Apache-2.0

    # Get these from /dev/disk/by-id DRIVES=" scsi-SATA_Hitachi_HDS7230_MN5220F323S79K-part1 scsi-SATA_Hitachi_HDS7230_MN5220F325UZMK-part1 scsi-SATA_ST2000DL003-9VT_5YD6MH88-part1 scsi-SATA_ST2000DL003-9VT_5YD70NHX-part1 scsi-SATA_WDC_WD20EARS-00_WD-WMAZA0374092-part1 "

    # The label name of your btrfs filesystem (mkfs.btrfs -L btrfs_pool) LABEL=btrfs_pool

    NUMDRIVES=$(echo $DRIVES | wc -w)

    die () { echo "$1" exit 1 }

    pwd="$(yourscript that returns crypt key)" if [ -z "$pwd" ]]; then echo -n "Decryption key? " stty -echo 2>/dev/null read pwd stty echo 2>/dev/null fi [ -z "$pwd" ]] && die "Didn't get a decryption key"

    # Here you can run a command to turn the disks on if they are on an # external power outlet. # turn-disks-on-cmd cd /dev/disk/by-id for i in 1 2 3 4 5 6 7 8 9 do if [ $(ls $DRIVES 2>/dev/null | wc -l) = $NUMDRIVES ]]; then break fi sleep 10 done # This is useful if the disks were just turned on. /etc/init.d/smartmontools restart

    for i in $DRIVES do dev=$(ls -l $i | awk '{print $11}' | sed "s#../..#/dev#") [ -z "$dev" ]] && die "Couldn't find device for $i" echo "$pwd" | cryptsetup luksOpen "$dev" "crypt_$(basename $dev)" || die "Couldn't decrypt $dev" echo "decrypt $dev" done btrfs device scan mkdir -p /mnt/btrfs_pool mount -v -t btrfs -o compress=zlib,noatime LABEL=$LABEL /mnt/btrfs_pool || die "Couldn't find btrfs $LABEL"

    2014/04/26 Very Late End of Season Powder Day at Kirkwood with 28 Inches of Freshies
    π 2014-04-26 01:01 in Nsnow, Snow
    So for those who still believe weather isn't getting more messed up, how is a super dry and crappy season that ends with 28 inches of unexplained storm (78cm) falling at kirkwood in just 24H?

    The storm didn't quite follow the forecast, it feel harder earlier and then didn't deliver friday night like it was supposed to, but by then so much had fallen that it didn't matter.
    In hindsight, Johannes and I should have arrived for Friday, noon to get some of the fresh cleaning tracks action, but eh, getting there for saturday morning, wasn't that bad.

    More people than I expected showed up, but given the forecast, it wasn't surprising:






    Unfortunately the weather got a bit warmer than it should and much of the powder was damaged by the end of the day (some even re-froze), but still, it was deep powder and good snow for the hours it lasted


    the kiddy side had been closed, so we had to ride a shuttle back to the front side
    the kiddy side had been closed, so we had to ride a shuttle back to the front side




    pretty narrow, and many rocks...
    pretty narrow, and many rocks...



    Due to ice, I slid down on top of these rocks, and jumped feet down and on my butt over the rock to land onthe other side. I got lucky, could have been worse...


    A big thanks to Johannes for getting us there and back and Jim for having us at his condo.

    2014/04/26 Btrfs Tips: Cancel A Btrfs Scrub That Is Already Stopped
    π 2014-04-26 01:01 in Btrfs, Linux

    How to cancel a btrfs scrub that won't cancel

    In some cases, btrfs scrub can be interrupted in a way that leaves it in a half state. State is stored in /var/lib/btrfs/scrub.status.UUID and if the relevant file indicates that scrub is still running (even though it is not), a new scrub cannot be started, nor the already stopped one cancelled.

    This is fixed as shown below:

    Problem:

    gargamel:~# btrfs scrub start -d /dev/mapper/dshelf1
    ERROR: scrub is already running.
    To cancel use 'btrfs scrub cancel /dev/mapper/dshelf1'.
    gargamel:~# btrfs scrub status  /dev/mapper/dshelf1
    scrub status for 6358304a-2234-4243-b02d-4944c9af47d7
            scrub started at Tue Apr  8 08:36:18 2014, running for 46347 seconds
            total bytes scrubbed: 5.70TiB with 0 errors
    gargamel:~# btrfs scrub cancel  /dev/mapper/dshelf1
    ERROR: scrub cancel failed on /dev/mapper/dshelf1: not running

    Fix:

    gargamel:~# perl -pi -e 's/finished:0/finished:1/' /var/lib/btrfs/*

    Verification:

    gargamel:~# btrfs scrub status  /dev/mapper/dshelf1
    scrub status for 6358304a-2234-4243-b02d-4944c9af47d7
            scrub started at Tue Apr  8 08:36:18 2014 and finished after 46347 seconds
            total bytes scrubbed: 5.70TiB with 0 errors
    gargamel:~# btrfs scrub start -d /dev/mapper/dshelf1
    scrub started on /dev/mapper/dshelf1, fsid 6358304a-2234-4243-b02d-4944c9af47d7 (pid=24196)
    2014/04/17 Simraceway/Sears Point Formula 3
    π 2014-04-17 01:01 in Cars, Ncars
    After learning from Nico at Sears in an R8 some time back, and he more recently got me down to a 2:00 at TH (full course), it was time for me to come back to Sears and this time learn to drive their Formula 3 Cars.

    It was a 2 day school, which started with getting us used to the cars, including shifting up and down without the clutch for me. My feet were too wide and I just could not put one foot on the clutch and another one on the brakes, they didn't fit. As a result, I got to learn to downshift without the clutch by "simply" braking and revmatching with the same foot.
    We had some class time:






    Nico gave us an intro to the car
    Nico gave us an intro to the car

    Et voila, c'est facile! :)
    Et voila, c'est facile! :)

    Each car had full datalogging that the MX crew could download for us
    Each car had full datalogging that the MX crew could download for us

    The cars had a 4 cyclinder turbo engine that could be tuned up to 300hp. Lots of power for a car that weighs nothing. It can corner at 3G, more than your body tells you should be able to make a turn :)



    We did some paddocks exercises to learn oversteer and understeer control as well as downshifting under braking:


    We were a small group, just 5 of us:


    On the 2nd day, we got to drive the track untethered:

  • First session taken from GoPro:
  • Second session taken from Google Glass (better view):

  • After our last session, we got to see the data:


    What I learned was I definitely needed to hit the brakes harder, which was challenging since I also had to revmatch at the same time for downshifting. Also, I wasn't full throttle in some corners where the tires could stick but my brain wasn't used to the idea of 2G cornering yet. In the end, I was 0.25s slower than the fastest person, doh...

    To study for next time, here's a walkthrough of most corners:

    Good time was had by all, this was a great learning experience in "different" cars. Looking forward to Level 2 :)

    See more images for Simraceway/Sears Point Formula 3
    2014/04/09 Mathias' 0x28 birthday
    π 2014-04-09 01:01 in Public
    Jenny invited us all for a nice dinner for Mathias' BD. A good evening was had by all:











    See more images for Mathias' 0x28 birthday

    More pages: March 2024 February 2024 January 2024 December 2023 November 2023 October 2023 September 2023 August 2023 July 2023 June 2023 May 2023 April 2023 March 2023 February 2023 January 2023 December 2022 November 2022 October 2022 September 2022 August 2022 July 2022 June 2022 May 2022 April 2022 March 2022 February 2022 January 2022 December 2021 November 2021 October 2021 September 2021 August 2021 July 2021 June 2021 May 2021 April 2021 March 2021 February 2021 January 2021 December 2020 November 2020 October 2020 September 2020 August 2020 July 2020 June 2020 May 2020 April 2020 March 2020 February 2020 January 2020 December 2019 November 2019 October 2019 September 2019 August 2019 July 2019 June 2019 May 2019 April 2019 March 2019 February 2019 January 2019 December 2018 November 2018 October 2018 September 2018 August 2018 July 2018 June 2018 May 2018 April 2018 March 2018 February 2018 January 2018 December 2017 November 2017 October 2017 September 2017 August 2017 July 2017 June 2017 May 2017 April 2017 March 2017 February 2017 January 2017 December 2016 November 2016 October 2016 September 2016 August 2016 July 2016 June 2016 May 2016 April 2016 March 2016 February 2016 January 2016 December 2015 November 2015 October 2015 September 2015 August 2015 July 2015 June 2015 May 2015 April 2015 March 2015 February 2015 January 2015 December 2014 November 2014 October 2014 September 2014 August 2014 July 2014 June 2014 May 2014 April 2014 March 2014 February 2014 January 2014 December 2013 November 2013 October 2013 September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 February 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 November 2008 October 2008 September 2008 August 2008 July 2008 June 2008 May 2008 April 2008 March 2008 February 2008 January 2008 December 2007 November 2007 October 2007 September 2007 August 2007 July 2007 June 2007 May 2007 April 2007 March 2007 February 2007 January 2007 December 2006 November 2006 October 2006 September 2006 August 2006 July 2006 June 2006 May 2006 April 2006 March 2006 February 2006 January 2006 December 2005 November 2005 October 2005 September 2005 August 2005 July 2005 June 2005 May 2005 April 2005 March 2005 February 2005 January 2005 December 2004 November 2004 October 2004 September 2004 August 2004 July 2004 June 2004 May 2004 April 2004 March 2004 February 2004 January 2004 October 2003 August 2003 July 2003 May 2003 April 2003 March 2003 January 2003 November 2002 October 2002 July 2002 May 2002 April 2002 March 2002 February 2002 November 2001 October 2001 September 2001 August 2001 July 2001 June 2001 May 2001 April 2001 March 2001 February 2001 January 2001 December 2000 November 2000 October 2000 September 2000 August 2000 July 2000 June 2000 April 1999 March 1999 September 1997 August 1997 July 1996 September 1993 July 1991 December 1988 December 1985 January 1980

    Contact Email