Subject Re: [firebird-support] Data Lost...
Author Lester Caine
gsndelphicoder wrote:
> Hey all,
> I have a client using a tablet application I developed. We are using FB 1.5.5, developing with Delphi 7, using IBO 4.6.A, and the app is running on Windows XP Tablet Edition. The client entered data into the system all day and at the end of the day the tablet PC ran out of battery and shutdown(it didn't run through the shutdown process it just turned off). When he turned the tablet PC back on, all of the data he had entered that day was gone. The first thing i thought was that somewhere I had left a transaction uncommitted. I looked through my code and couldn't find this to be true. There were no Transaction started that weren't committed or rolled back within the same code block/procedure. Also, each time the data is saved/posted, which he did throughout the day, I am checking for uncommitted transactions and committing them. So, just to make sure of this I restored a backup of the DB made the day before and compared the Generators of several tables that would have
been incremented throughout the day as he was entering data in the app. All of the generator values were identical. From what I understand, these generator values are handled outside of transactions which means that even if my code had rolled back a transaction that somehow managed to stay open the entire day, the generators would still have been incremented.
> Does anyone have any experience with data loss due to a PC turning off unexpectedly?
Many moons ago ...
The problem is with Windows rather then Firebird - not that that helps :(
You need to make sure that 'forced write' is ACTUALLY working. We found that
until the file was actually closed the information M$ had cached waiting to
write was simply not saved.
It took a week to find the source of the nightly power fail in our case ( over
ten years ago now ) and the cleaner got a right bollicking for simply pulling
out a plug to plug her vacuum in! But by the time we had found that we had also
stopped it loosing the whole days data.
I an imagine that the 'tablet edition' has some more subtle changes to the
hardware interfaces but I THINK I had to switch a cache setting off directly on
the hard disk driver!

> This is kinda freaking me out. I don't want to lose this client and need to get to the bottom of this. He has be using this system for months with no problems until the PC turned itself off yesterday.

Lester Caine - G8HFL
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