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by Francois117
Wed Oct 10, 2018 4:21 pm
Forum: Advanced users
Topic: I want MySQL instead of MariaDB
Replies: 54
Views: 27195

Re: REAL MySQL instead of MariaDB

We use the Mysql command "CHECKSUM TABLE ZZZ EXTENDED;" to compare tables on our back end server database with raspberries in the field as part of a differential table sync. Our table currently has about 100k rows and this is quite efficient. We update about 1 - 10 rows per minute and run the checks...
by Francois117
Wed Apr 13, 2016 3:00 pm
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: filesystem write files - after reboot the old data is ba

I agree... I really want to trash it but I am developing a project on this hardware that will run in the field for many years. I need to know when that SD card goes bad - without knowing, the device will operate in a semi-working condition for a long time (until the ram fills up) risking back-end da...
by Francois117
Wed Apr 13, 2016 7:46 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: filesystem write files - after reboot the old data is ba

in theory; if the SD card is not retaining data, it will NOT retain data through umounting and mounting. If the data are only being retained in the kernel's buffer cache and not on the card, just dropping the caches should be sufficient to make recent changes disappear. touch TESTFILE stat TESTFILE...
by Francois117
Tue Apr 12, 2016 8:39 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: need tool for detect read-only SD card

Add a USB stick, copy writes to that and compare with SD ... add more hardware, that can fail too? ;) I get the realtime clock initialised about two minutes after boot - maybe I can read a file that should have yesterday's date... if it has yesterday's date, then write today's date to it, and then ...
by Francois117
Tue Apr 12, 2016 8:18 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

need tool for detect read-only SD card

My huge issue with this is that I can't easily detect when the card goes faulty! The operating system continues normally and shows all the new disk contents as if nothing is wrong and everything has been written. As fas as I can see there are only two ways of detecting this: 1) write more incompress...
by Francois117
Tue Apr 12, 2016 8:09 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

next card worked fine - much slower.

So I booted another pi with a similar version of ubuntu 14. - also created a recursive directory structure but it took much longer. - copying recursive directories is very slow. - the disk access LED stayed on long after the writes "finish" and control comes back to the command line. - sync took 1 m...
by Francois117
Tue Apr 12, 2016 7:06 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

more tests...

This is the card: http://i.imgur.com/W5WS7Ag.jpg ... test 1: vim 1.test and I entered many lines of text in it. Save. cat 1.test shows the contents of the file. reboot. file gone. no file, no contents. ... test 2: vim 2.test and I entered many lines of text in it. Save. cat 2.test shows the contents...
by Francois117
Mon Apr 11, 2016 8:14 pm
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: filesystem write files - after reboot the old data is ba

Sooo... Three days later. I managed to find an older version of my development SD card and cloned it onto the SD card of the system that was showing this weird non-write error. And guess what - after the dd, the SD card still had all the old data! Like the dd did not happen! Somehow it fools the ubu...
by Francois117
Fri Apr 08, 2016 4:30 pm
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: filesystem write files - after reboot the old data is ba

df -h Filesystem Size Used Avail Use% Mounted on /dev/mmcblk0p2 7,2G 2,3G 4,7G 33% / devtmpfs 458M 4,0K 458M 1% /dev none 4,0K 0 4,0K 0% /sys/fs/cgroup none 93M 312K 93M 1% /run none 5,0M 0 5,0M 0% /run/lock none 462M 0 462M 0% /run/shm none 100M 0 100M 0% /run/user /dev/mmcblk0p1 64M 20M 45M 31% /...
by Francois117
Fri Apr 08, 2016 1:44 pm
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

Re: filesystem write files - after reboot the old data is ba

Thanks for the reply, Heater. I have yanked the power many times. Out in the field, the system must be able to deal with power failures. It has caused no problems in the past, and he question of whether it caused the current state is debatable. The current state seems to have occurred on multiple de...
by Francois117
Fri Apr 08, 2016 6:41 am
Forum: General discussion
Topic: filesystem write files - after reboot the old data is back
Replies: 34
Views: 7963

filesystem write files - after reboot the old data is back

Okay this is a really weird problem occurring on two raspberry pi systems with their respective 8GB SD memory cards: Simple example: When I write files to the disk, it looks like the files are written. I can edit a file vim test.dat, enter text into it, save. ll will list the file. cat will show the...

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