OBJECT STORE ON BERKELEY DB
---------------------------

OSBDB is an implementation of an object store that uses Berkeley DB as
the underlying storage. It is meant to be an alternative to EBOFS.

BUILDING
--------

You will need to have Berkeley DB installed, including the developent
packages. We've tested this with Berkeley DB 4.4.20 on Ubuntu 6.10.

To compile OSBDB support, you need to pass the argument "want_bdb=yes"
to "make." If you don't specify this, OSBDB and all its associated
support is not included in the executables.

RUNNING
-------

To use OSBDB in Ceph, simply pass the --bdbstore flag to programs. You
don't need to create a "device" for OSBDB ahead of time; Berkeley DB
will take care of creating the files. You also *cannot* use a raw
device as your store -- it must be regular file.

OSBDB additionally accepts the following flags:

  --bdbstore-btree         Configures OSBDB to use the "Btree"
                           database type for Berkeley DB. The default
                           database type is "Hash".

  --bdbstore-hash-ffactor  Sets the "fill factor" for the hash
                           database type. Takes an integer argument.

  --bdbstore-hash-nelem    Sets the "nelem" parameter for the hash
                           database type. Takes an integer argument.

  --bdbstore-hash-pagesize Sets the page size for the hash database
                           type. Takes an integer argument.

  --bdbstore-cachesize     Sets the cache size. Takes an integer
                           argument, which must be a power of two, and
                           no less than 20 KiB.

  --bdbstore-transactional Enable (in-memory-only) transactions for
                           all operations in the OSBDB store.

  --debug-bdbstore         Set the debug level. Takes an integer
                           argument.