tdb questions

[Volker Lendecke]

On Fri, May 24, 2013 at 02:47:17PM +0200, Daniele Dario wrote:
> thanks so much for the response.
> 
> The system power has a battery backup which gives us 3 min of power and
> notify the application that line power has gone so I'm able to close all
> handles but I can't perform a clean shut down to the system because if
> power comes on again while it is shutting down I'm not able to restart
> it. I need to completely remove power to terminate the shut down in
> order to allow a (re)start. If line power comes up within the 3 min of
> battery power, the application would be notified and re-open files.
> 
> Said this, would it be enough to use tdb_close when we loose line power
> to keep tdbs safe?

Without transactions, no. You can never be sure the system
has written the buffers to disk without fsync and barriers.

> About the FS actually it is an ext2 partition on a DiskOnModule so to
> enable write barriers have to move to (at least) ext3 so I'll start
> looking on that.

Ok, ext2. If that has met your persistence and recovery
requirements, I think you don't have to bother with
transactions at all. Just use tdbs without transactions and
reinstall the system when it's hosed.

Volker

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