What is the difference between different blobstorage ZODB layouts?

Question

The blobstorage ZODB directory contains a .layout file with the string 'lawn', 'bushy'.

What is the difference between the various blob storage directory formats?

Answer 1

Explained here: http://svn.zope.org/ZODB/trunk/src/ZODB/tests/blob_layout.txt?rev=101802&view=markup

FTA:

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BLOB Catalog Layouts

The internal directory structure of blob is determined by the so-called layouts . The current default layout is called bushy .

The original blob implementation used a layout that we now call lawn and which is still available for backward compatibility.

Layouts implement two methods: one to calculate the relative path for the OID and one to return the relative path back to the OID.

Our terminology is about the same as in DirectoryStorage .

It also describes formats in detail.

Answer 2

You don’t have to worry about the layout at all; lawn exists only for backward compatibility.

If you have a blobstorage lawn layout (you get a warning in the log if you do) and want to switch to a bushy layout, use the migrateblobs script; here is the build part for creating the script:

 [migrateblobs] recipe = zc.recipe.egg eggs = ZODB3 entry-points = migrateblobs=ZODB.scripts.migrateblobs:main 

Turn off all ZEO instances and servers, back up the data warehouse and run the script in the blobstorage directory:

 $ mv var/blobstorage var/blobstorage-lawn $ bin/migrateblobs var/blobstorage-lawn/ var/blobstorage 

var/blobstorage will then contain the transferred drops using the bushy layout.