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From Emmanuel Lecharny <>
Subject Re: Usage of JDBM : Experience feedbacks
Date Tue, 28 Oct 2008 14:45:31 GMT
Howard Chu wrote:
> Robert Mertens wrote:
>> Hi Florent,
>> I am using the JDBM as a part of the Apache Directory Server. I am
>> switching from OpenLDAP because it's Berkeley did not always shut down
>> properly.
> I find that quite difficult to believe. On a properly configured 
> installation we never see corruption or data loss. We've even tested 
> on machines that crashed due to failing DRAMs and the database 
> (containing over 1 terabyte of data) still recovered in under 2 
> minutes on the subsequent reboot (after replacement of bad memory).
> Ever since BerkeleyDB 4.2 came out, we've had no data corruption 
> issues with BerkeleyDB...
I must say that I trust Howard on that ...
>> The JDBM seems to do the job, but does not seemt to handle
>> emergency shutdowns very well(or is it the Apache Directory Server?).
It depends on many factors. If you don't select a sync on write (ie, 
differing writes for better performances), you may lose data. Otherwise, 
a crashed JDBM base may need some recovery. We have to investigate this.
>> The BTree was corrupted when shutting down the machine it is running on
>> when we, at the same time, performed actions against the Directory
>> Server where we deleted entries. The result was that the Directory
>> Server could not be restarted again without replacing the JDBM. I am
>> waiting for Apache Directory Server team to implement a failover model
>> for such occasions.
This is something we have in our roadmap for 2.0.

cordialement, regards,
Emmanuel L├ęcharny

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