[ZODB-Dev] Blobstorage shrinks only after the second pack operation - bug or feature?

[Jim Fulton]

On Sun, Dec 30, 2012 at 12:22 PM, Andreas Jung <lists at zopyx.com> wrote:
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> Jim Fulton wrote:
>> On Sun, Dec 30, 2012 at 3:50 AM, Andreas Jung <lists at zopyx.com>
>> wrote:
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>>> I noticed a strange behavior with packing a storage having lots of
>>> data in a blob storage (Plone 4.2, Zope 2.13).
>>>
>>> I had a large Plone site (5 GB of data in blobstorage) in a
>>> dedicated storage. I removed the Plone Site object and packed the
>>> storage through the Zope 2 database management screen. The size of
>>> the Data.fs went down however the blobstorage size remained the
>>> same. Packing a second removed the obsolete data from the blob
>>> storage.
>>>
>>> So why do I have to pack two times in order to get a minimized
>>> blob storage?
>>
>> Without knowing more details, it's impossible to know.
>>
>> What did you have pack-keep-old set to?
>
> I used the default of the Zope 2 UI which is 0 (days).

You didn't answer my question.  I didn't ask how many days you packed to.
I asked if you set pack-keep-old. I'm guessing from your response that you
didn't.

If you don't set pack-keep-old to false, then old blobs are kept around, just
like the file-storage file, except that, rather than making copies, hard links
are created.

The second time you packed, the old links would be removed, freeing up
the space taken by the old blobs.

Jim

-- 
Jim Fulton
http://www.linkedin.com/in/jimfulton
Jerky is better than bacon! http://zo.pe/Kqm