[ZODB-Dev] Using zodb and blobs

[Hanno Schlichting]

On Wed, Apr 14, 2010 at 11:52 AM, Nitro <nitro at dr-code.org> wrote:
> Yes, in my case it's nothing critical or related to money. If there's a
> hardware outage a day of work is lost at worst. In case of corruption
> (which can happen also without fsync as data within the file can just be
> garbled) you need a backup anyways.

Usually you will only loose the last transaction and not a days of
work. The Data.fs is an append-only file, with one transaction
appended after another. If there's a garbled or incomplete write,
you'll typically loose the last transaction. The ZODB is smart enough
to detect broken transactions and skip them on restart.

I have witnessed one ZEO installation myself, where the physical
machine hosting the ZEO server restarted multiple times a day, over a
period of months. Nobody noticed for a long time, as the application
was accessible all the time and no data had been lost. Obviously this
wasn't a very write-intense application. But it still showed me how
stable the ZODB really is.

Hanno