"Tomalla, Wolfram" <TM_at_ProCom.de> ,in message <44392638B0B9D011B7130000C09541E0
	2AC7DD_at_procomres1>, wrote: 

> The problem is thee are no replicated Databases that realy
> hold the Data faliles except Oracle. And an Oracle
> istallation would cost us $25.000 - $30.000 per system.
> All the other Databases actualy only support a warm standby.
> That means, if the Database commited a transaction, the 
> data is only on the machine the database system is running on.
> The data will be copied to the other system soon, but if the 
> mashine crashes imediadly after the commit there is wrong 
> data on the standby server. But it must not happen, that our
> database contains wrong data about the situation that is 
> controled.

  Then you better knuckle down and pay the money.  If you can't pay the money,
then you need to get the hell out of the business.  Getting a distributed
database to work correctly takes a massive engineering effort, and until
everybody and their sister wants one, it's going to be an expensive market.

> check on the RAID system, mount it and restart the database.
> This works ok, but the filesystem check on a 4 or 8 GB ext2
> partition takes far to long. So switching to the standby server
> will take several minutes.

  There are commercial solutions provided by companies like Veritas with their
journaling filesystems and High Availability daemons.


  Of course, one day there will be free software versions of these tools,
maybe soon;  but I pity the fool who deploys it in a mission critical capacity
before it's been shaken out.

-- 
Bob Forsman                                   thoth_at_gainesville.fl.us
           http://www.gainesville.fl.us/~thoth/