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<?>Bdb to FSFS - Any gotchas to watch out for<?>

From: Kahn, Peter <Peter.Kahn_at_ironmountain.com>
Date: 2006-02-23 18:35:36 CET

Hi, I ran into a problem with my repository that has finally convinced
me to convert from BDB to FSFS for my repository backend. I'd like to
thank you all for all the help you have given me over the past 18 months
as it has been essential in keeping my environment up and my blood
pressure down.

My latest problem was that users got "bdb: Lock table is out of
available locker entries" upon commit. I ran out of lockers and my fix
was to recover followed by changing the lk_max_ settings from 2000 to
8000. The choice of value was arbitrary as I wasn't sure how determine
just how many database trees I had as recommending in the Sleepykat
tuning page.

I have a Linux based 7 GB repository with about 25000 revisions that is
accessed through svnserve and apache. It seems like a large environment
to me and I am pretty sure that I will hit more tuning issues with BDB
as I go forward. I don't have the time to become a BDB tuning expert
(although it is interesting).

I am using the conversion method I saw on this list and I should be down
for about 3 hours:
        svnadmin create --fs-type FSFS ./repos_fsfs >> log 2>&1
        svnadmin dump ./repos | svnadmin load ./repos_fsfs >> log 2>&1

I looked in the FSFS repository for tuning options, didn't really find
any and I really want to proactive on tuning/monitoring (I have some
cron jobs now dumping the output of db_stat into a file). So, with that
in mind here are my questions:

Q1. What tuning options are there for FSFS repositories?
        is there a good guide somewhere?

Q2. What is the best way to monitor a FSFS repository?

Q3. What are the gotchas for converting to a FSFS repository?
        - all local developer workspaces will need to be checked-out
anew
          as switch will not work due to the fact that the old repos and
          the new will be two different repositories

Q4. What are the gotchas for running a FSFS repository?

Q5. What are the best practices for FSFS repository health?
        - Is there some thing I should do on a regular basis
          to handle skip-deltas and delta combination to improve
          performance? [deltify?]

Q6. What kinds of corruption do people see with FSFS and how have they
dealt with it?
        The red bean book say "FSFS's inability to be 'wedged'
        when something goes wrong" but I'm wondering if anyone
        has seen problems?

        - should a rev file go missing due to file system error or
          operator error what would my options be?

        || could I extract the file off of a backup and insert
        || in into the right location to recover it?


Again thanks for all the help....


Related Docs:
http://blog.parthenoncomputing.com/dbxml/archives/2005/03/index.html
http://www.sleepycat.com/xmldocs/ref/lock/max.html

http://svnbook.red-bean.com/nightly/en/svn.reposadmin.html#svn.reposadmi
n.basics.backends

http://svn.collab.net/repos/svn/trunk/subversion/libsvn_fs_fs/structure

 



--
Peter Kahn
peter.kahn@ironmountain.com
Mobile: 508-958-2996
IM: pkahn@imserver, citizenkahn@jabber80.com,
citizenkahn@googletalk.com, citizen_kahn@yahoo.com
Iron Mountain Digital

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Received on Thu Feb 23 18:37:48 2006

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