Long Walk (Oct 20 2009)


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Profile Matt Lebofsky
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Message 941598 - Posted: 20 Oct 2009, 22:19:49 UTC

Recovering from the weekly maintenance outage right now, during which we took care of a couple extra things (above and beyond the usual mysql database compression/dumping). Eric replaced a failed root drive on his hydrogen database server. While he was at it, he upgraded the system's OS (it was way out of date). Meanwhile, I took the opportunity to finally bite the bullet and remove the SETI network's reliance on this server, as it hosted (for only historic reasons) the 32-bit libraries for informix - so when this server went down pretty much everything hung waiting for it to return. So this pointless dependency is no more, which is a bit of a relief.

I also added a couple recently donated solid state drives to mysql master database server mork, if only to create a tiny RAID1 on which to put mysql logs, and thus hopefully reduce disk contention on the data drives (which currently also hold the logs). We'll implement that new mini RAID over the course of the coming week.

Also, it turns out mysql replication was broken for the beta project this whole past week. Oops. So tomorrow we'll start the recovery of that (using today's mysql dump). I also turned of "show tasks/results" as the project recovers. Maybe I'll turn that on tomorrow after the smoke clears.

I'm still pulling up files for future software radar blanking analysis/processing. It's really slow given our various network bottlenecks (real or imposed).

Oh yeah.. I guess this is also technical news: Most days I take the train to downtown Berkeley, walk across campus, then ride the hill shuttle up to the lab (which is 1.5 miles up a very tall/steep hill). The shuttle's brakes failed on the way home - or at least showed enough signs of pre-failure such that the driver refused to go any further. He called dispatch to get another bus, but nobody was responding to his pleas. Given my tight schedule (and lack of cell phone service on the hill) I had no choice but to walk all the way down the hill myself, which wasn't the first time, and was no big deal - just terribly annoying.

- Matt

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Message 941609 - Posted: 20 Oct 2009, 22:48:19 UTC

WOW...I see 148 Astropulse wu ready to send...enough for everyone ha =)

Welldone for the weekly maintenance Master Matt & Master Eric. walking is healthy, but if we have something to be pursued, walking becomes very annoying ".)
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Message 941651 - Posted: 21 Oct 2009, 3:44:28 UTC

Thanks for the updates and all the good work. Getting rid of failure possibilities is most important.

As to failures of breaks, you of all people should know about failures. If it can go wrong it will and in the way to affect the greatest number of people in the most aggravating manner.

Next time you see the driver thank him and then get the story of what the mechanics found.

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Message 941699 - Posted: 21 Oct 2009, 7:32:03 UTC - in response to Message 941598.

I also added a couple recently donated solid state drives to mysql master database server mork, if only to create a tiny RAID1 on which to put mysql logs, and thus hopefully reduce disk contention on the data drives (which currently also hold the logs). We'll implement that new mini RAID over the course of the coming week.


Yea!

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Message 941739 - Posted: 21 Oct 2009, 13:38:26 UTC - in response to Message 941598.

I also added a couple recently donated solid state drives to mysql master database server mork, if only to create a tiny RAID1 on which to put mysql logs, and thus hopefully reduce disk contention on the data drives (which currently also hold the logs). We'll implement that new mini RAID over the course of the coming week.


You might be surprised how much of a performance improvement that makes. I'm not sure about MySQL, but it helps most other RDBMS systems.

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Message 941759 - Posted: 21 Oct 2009, 15:41:26 UTC - in response to Message 941598.

... 1.5 miles up a very tall/steep hill). The shuttle's brakes failed on the way home - or at least showed enough signs of pre-failure such that the driver refused to go any further. ...

Is this where we can all wax lyrically and very technically about how the shuttle bus should have an electrical or pneumatic or hydraulic retarder that doesn't wear out like normal brakes do? Or even how it should have regenerative braking?... Or even how a gravity balanced funicular should be installed so that you can energy efficiently get there and back and enjoy the views aswel!?

At least your exercise was downhill. Good exercise also?


I once sprinted uphill to a medical to get there just-in-time to walk straight into the tests. They were very happy about my heart rate but a bit puzzled from the results of some of the 'various fluids' tests... Until they asked if I'd been doing a lot of running...


Good luck with reducing the multiple cross-mounts and cross-dependencies!

Regards,
Martin


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Message 941780 - Posted: 21 Oct 2009, 16:58:37 UTC - in response to Message 941759.
Last modified: 21 Oct 2009, 17:04:20 UTC

... 1.5 miles up a very tall/steep hill). The shuttle's brakes failed on the way home - or at least showed enough signs of pre-failure such that the driver refused to go any further. ...

Is this where we can all wax lyrically and very technically about how the shuttle bus should have an electrical or pneumatic or hydraulic retarder that doesn't wear out like normal brakes do? Or even how it should have regenerative braking?... Or even how a gravity balanced funicular should be installed so that you can energy efficiently get there and back and enjoy the views aswel!?


All brakes eventually fail - it is in the nature of the brakes turning kinetic energy (motion) and/or potential energy (gravity + height) into thermal energy.

Since the bus is probably has a Diesel motor, another solution might be available - the "engine retarder" or "Jacobs brake", usually reffered to as "Jake brake". If you've ever been next to a big-rig truck on a downgrade, you've heard them, the BWW-WWW-WWW-WWW from the exhaust. I know that Jakes can be fitted to a bus engine, although (apparently...) Cal's buses don't have the option...

I'm very surprised that the option wasn't ordered, given the steepness of Centennial Drive on the Cal campus...

Long-haul trucker living in Albany, CA - next door to the People's Republic...
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Message 941855 - Posted: 21 Oct 2009, 23:55:26 UTC - in response to Message 941780.

... 1.5 miles up a very tall/steep hill). The shuttle's brakes failed on the way home - or at least showed enough signs of pre-failure such that the driver refused to go any further. ...

Is this where we can all wax lyrically and very technically about how the shuttle bus should have an electrical or pneumatic or hydraulic retarder that doesn't wear out like normal brakes do? Or even how it should have regenerative braking?... Or even how a gravity balanced funicular should be installed so that you can energy efficiently get there and back and enjoy the views aswel!?


All brakes eventually fail - it is in the nature of the brakes turning kinetic energy (motion) and/or potential energy (gravity + height) into thermal energy.

Since the bus is probably has a Diesel motor, another solution might be available - the "engine retarder" or "Jacobs brake", usually reffered to as "Jake brake". If you've ever been next to a big-rig truck on a downgrade, you've heard them, the BWW-WWW-WWW-WWW from the exhaust. I know that Jakes can be fitted to a bus engine, although (apparently...) Cal's buses don't have the option...

I'm very surprised that the option wasn't ordered, given the steepness of Centennial Drive on the Cal campus...

Long-haul trucker living in Albany, CA - next door to the People's Republic...

In many residential areas, Jakes are illegal because of the noise. Regenerative systems (of any sort) can dramatically reduce wear on the breaks
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Message 942009 - Posted: 22 Oct 2009, 19:04:20 UTC

There are a couple places around here in the mountains where jake brakes are prohibited because of the avalanche danger. They really are loud.
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Message 942028 - Posted: 22 Oct 2009, 20:29:18 UTC

Odd thing about the "jake Break" They can be made to be quiet, but I have yet to see one in common service that is. It would cost ( some ) and that is the rub.


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Message 942052 - Posted: 22 Oct 2009, 23:37:20 UTC - in response to Message 942028.
Last modified: 22 Oct 2009, 23:47:57 UTC

Odd thing about the "Jake Brake" They can be made to be quiet, but I have yet to see one in common service that is. It would cost ( some ) and that is the rub.


Cheers.


What's really odd is that jakes, as delivered by the manufacturer (Freightliner, at least...) are quite quiet - it's the truckers themselves who make them louder, by making the exhaust pipe larger in diameter after the muffler! (think megaphone...)

Two different models (Century, Columbia) of Freightliner driven, both with "quiet jakes" - no louder than the same tractor at full acceleration! Both trucks had "as delivered" exhaust systems.

And truckers have only themselves to blame for Jake brake restrictions - because they use them where they shouldn't! (Jakes are meant for long and/or steep downslopes, [like Centennial Drive, or Donner Pass: which are both...] and not for ordinary stopping.

Centennial Drive doesn't have a Jakes restriction AFAIK... (21 year area resident...)
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Message 942075 - Posted: 23 Oct 2009, 0:30:26 UTC - in response to Message 942052.

Odd thing about the "Jake Brake" They can be made to be quiet, but I have yet to see one in common service that is. It would cost ( some ) and that is the rub.


Cheers.


What's really odd is that jakes, as delivered by the manufacturer (Freightliner, at least...) are quite quiet - it's the truckers themselves who make them louder, by making the exhaust pipe larger in diameter after the muffler! (think megaphone...)

Two different models (Century, Columbia) of Freightliner driven, both with "quiet jakes" - no louder than the same tractor at full acceleration! Both trucks had "as delivered" exhaust systems.

And truckers have only themselves to blame for Jake brake restrictions - because they use them where they shouldn't! (Jakes are meant for long and/or steep downslopes, [like Centennial Drive, or Donner Pass: which are both...] and not for ordinary stopping.

Centennial Drive doesn't have a Jakes restriction AFAIK... (21 year area resident...)

Yes, there are places where Jakes are required - most of the passes Eastbound out of the Rockies in Colorado come to mind. Most of these are long, steep, and winding. Think 5K foot drops at 10 to 14% grade. "Trucks use lower gear, check your brake temperatures, use your Jakes" is one sign that I seem to recall having seen shortly before "Runaway truck ramp 1 mile".

There are places where they shouldn't be used - on 2$ grades in cities comes to mind.
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Message 942299 - Posted: 23 Oct 2009, 17:53:31 UTC - in response to Message 942075.
Last modified: 23 Oct 2009, 17:55:38 UTC


Yes, there are places where Jakes are required - most of the passes Eastbound out of the Rockies in Colorado come to mind. Most of these are long, steep, and winding. Think 5K foot drops at 10 to 14% grade. "Trucks use lower gear, check your brake temperatures, use your Jakes" is one sign that I seem to recall having seen shortly before "Runaway truck ramp 1 mile".

There are places where they shouldn't be used - on 2$ grades in cities comes to mind.


I know that I've used Jakes on both I-80 (EB) and I-70 (WB)...

another place that truckers are notorious for using them, and shouldn't... freeway off-ramps!
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Message 942863 - Posted: 26 Oct 2009, 4:44:22 UTC - in response to Message 942299.

around here truckers, and espically dump trucks use the jake brakes as much as they can in order to minimise brake wear. south florida is virtually flat land so there is no grades. if they are in my neighbourhood with a load of dirt, i see them use the jake brake to slow down to a virtual crawl and only use the air brakes as the last second to actually come to a complete stop 9if they even bother to do that which most do not).

i have no problem with jake brakes in my neighbourhood. i find the sound comical.

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Message 942882 - Posted: 26 Oct 2009, 12:09:00 UTC - in response to Message 942863.

around here truckers, and espically dump trucks use the jake brakes as much as they can in order to minimise brake wear. south florida is virtually flat land so there is no grades. if they are in my neighbourhood with a load of dirt, i see them use the jake brake to slow down to a virtual crawl and only use the air brakes as the last second to actually come to a complete stop 9if they even bother to do that which most do not).

i have no problem with jake brakes in my neighbourhood. i find the sound comical.

It is not much of a problem if everyone is awake. Now try having several dozen of them do that at 2 a.m. slowing for the off ramp near your bedroom window. This is the nightmare.
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