Concurrent Access Methods and NFS

#1

The product I am working in uses an older version of BDB - 2.4.14.
Unfortunately, the data is stored on NFS, using a PERL library to lock
it before use -LockFile::Simple. Also, unfortunately, this library's
documentation states that this locking is not immune to race
conditions.
My question is this, in the later versions of BDB, Concurrent Access
Methods was added. Does this resolve the issue of having multiple
processes accessing the same data store over NFS ?

#2

One other question - has the issue been resolved about the data
corruption that occurs if the process doing the writing aborts ?

#3

tiddlywink wrote:

Quote:

My question is this, in the later versions of BDB, Concurrent
Access Methods was added. Does this resolve the issue of
having multiple processes accessing the same data store
over NFS ?
The short answer is no. There is more detail in the FAQ entry here:

http://dev.sleepycat.com/resources/faq_show.html?id=125

Quote:

using a PERL library to lock it before use -LockFile::Simple
From the documentation on this library it does not seem to provide
safety in an NFS environment anyway:

"It is not meant to be exempt from all race conditions, especially over
NFS. "
http://search.cpan.org/~ram/LockFile....2.5/Simple.pm

Quote:

One other question - has the issue been resolved about the data
corruption that occurs if the process doing the writing aborts ?
I think this is answered in the above FAQ as well - let me know if not.

- Alex

#4

Thanks for the response, it answers my first question, but not the
second. I still need to know if corruption can occur when the process
writing to the database seg faults, or aborts for some reason ? (the
latest version, not 2.4.14).
Thanks

#5

tiddlywink wrote:

Quote:

Thanks for the response, it answers my first question, but not the
second. I still need to know if corruption can occur when the process
writing to the database seg faults, or aborts for some reason ? (the
latest version, not 2.4.14).

Assuming that you are going to use a transactional data store, and not
network based file systems. Current versions of DB will deliver ACID
(http://databases.about.com/od/specif...cts/a/acid.htm) compliant
data storage.

This means that the database will always be left in a recoverable state
- even after a segmentation fault in the process writing to a database.

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Concurrent Access Methods and NFS

comp.databases.berkeley-db comp.databases.berkeley-db

Concurrent Access Methods and NFS - 04-18-2006 , 10:16 AM

Re: Concurrent Access Methods and NFS - 04-18-2006 , 02:53 PM

Re: Concurrent Access Methods and NFS - 04-19-2006 , 06:17 PM

Re: Concurrent Access Methods and NFS - 04-20-2006 , 01:41 PM

Re: Concurrent Access Methods and NFS - 04-20-2006 , 06:24 PM