NEHA Laptop

Re: NEHA Laptop

Postby KevinGale » Fri Feb 06, 2015 8:36 pm

RacingFrog wrote:I have done that with the Rallycross live timing, I know it's going to be a significant investment in time for training and support. But I'll train you first Kevin ;)


Can't fault that logic. :-)
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Re: NEHA Laptop

Postby KevinGale » Sun Feb 08, 2015 12:58 pm

Yeah no problem. I'll order one of each.
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Re: NEHA Laptop

Postby KevinGale » Tue Apr 28, 2015 9:09 pm

As an update I have both of the Thinkpad X61s models up and running. I threw in a 500 Gb hard drive in each that I had in a drawer and installed Win 7 32 bit. They both seem to run everything just fine and the screens work outside. Also really nice is that the hard drives will swap between the two almost identical laptops. I can pull the drives swap then between the two computers and they both boot. So no only will we have a backup laptop but drives are also swap-able which makes it more likely that some combination will work worst case.

After having a laptop die at Philo I also thought about making the processes of error recovery easier. We always write down the times so we have a paper backup but at Philo that meant we had to enter all the data from the runs before the laptop died. I'm now planning on running the app off a SD card. If the laptop dies I can pull the card and put it in the other laptop or even my personal laptop and in theory move forward without having to enter all the missing run data to that point.

The SD card will also mean that I will probably post the results sooner after an event. When I get home I can just pop the SD card out of the NEHA laptop and bring it inside and pop it into my personal laptop. That will be a lot easier than bringing in the NEHA laptop and setting it up and then doing a file transfer.
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Re: NEHA Laptop

Postby sachilles » Wed Apr 29, 2015 6:49 am

Cool! :!:
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Re: NEHA Laptop

Postby drummingpariah » Wed Apr 29, 2015 7:11 am

SD flash is relatively volatile for storage, so if its possible, have the app save to the hdd and the sd card. Maybe im being a little overly cautious here, but im used to being concerned about the sixth 9 in availability (99.9999%) and try to have at leadt two failsafes for every critical system. Is that possible?

Thats great news though, I'm really pleased that those laptops are working out.
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Re: NEHA Laptop

Postby KevinGale » Wed Apr 29, 2015 10:11 am

drummingpariah wrote:SD flash is relatively volatile for storage, so if its possible, have the app save to the hdd and the sd card. Maybe im being a little overly cautious here, but im used to being concerned about the sixth 9 in availability (99.9999%) and try to have at least two failsafes for every critical system. Is that possible?


That is good feedback and the kind of thing I was looking for. I've been doing some research on this trying to figure out if this is really a good idea. I could modify the app to use the SD as some kind of backup but there is a database involved and changing things to mirror to a live database is more work than I want right now. Maybe I will just step back from this right now and just take the swap-able hard drives as a step in the right direction.
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Re: NEHA Laptop

Postby drummingpariah » Sat May 02, 2015 7:51 am

I know with mysql at least, a backup to a known-good directory is easy:
Code: Select all
mv /local/datadump.sql /local/datadump.sql.bak
mysqldump --all-databases > /local/datadump.sql


I assume you could just do something like that for each write, or every minute, or similar to external media. You already have a spare machine ready to import that data, so powering the second machine up would be the difficult part. At least then you have a failsafe in data as well as a hardware failsafe.
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Re: NEHA Laptop

Postby KevinGale » Sat May 02, 2015 11:15 am

Yeah if I switched to a real database but what I'm using I don't think supports any style of backup while the system is running.

I've done some more research on SD cards and I don't see a reason they shouldn't work for what we want. Do you have any specific reasons you don't think it will work. Yes there are long term write issues but we won't bump into those since there isn't that much data written.

We actually don't need anything like 6 9's reliablity. A couple 9's might even work. :-) The data will be backed up in multiple locations so there is no chance of losing all the data. Worst case is losing a weekends worth of data and having to key it back in.

I have however had laptops fail. There are lots of things that can go wrong there. We have had to swap laptops due to water shorting out the system (Philo last year) , weird OS boot problem (once), and power port physical failure on the laptop.

My guess is the probability of some failure that results in us wanting to swap laptops is a lot higher than the probable failure of the SD card. And given it's other advantages of making my life easier I'm now leaning back towards trying it.
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Re: NEHA Laptop

Postby drummingpariah » Sat May 02, 2015 1:05 pm

I am being overzealous here. I dont seeany short term problems (within the next 5 years).
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