Why is dccd reporting database broken?

Vernon Schryver vjs@calcite.rhyolite.com
Fri Jan 20 04:28:28 UTC 2006

> From: Gary Mills <mills@cc.umanitoba.ca>

> I just noticed dbclean running at an unusual time on one of my DCC
> servers (dcc1).  The database seems quite large:
>   -rw-r--r--   1 daemon   other    2109800448 Jan 19 21:24 dcc_db-new
>   -rw-r--r--   1 daemon   other    2147483647 Jan 19 21:21 dcc_db
>   -rw-r--r--   1 daemon   other    2147483647 Jan 19 18:28 dcc_db-old
> On the other one (dcc2), the files are smaller:
>   -rw-r--r--   1 daemon   other    1368858624 Jan 19 21:24 dcc_db

> The filesystem is 50% full after the rebuild completed.  Has the database
> hit a size limit?  Has the filesystem run out of fragments?  As I recall,
> I created it with a fragment size of 4096, so this should never happen.

Some systems really do not like mmap() regions larger than 2 GBytes.
The last few dozen versions of the DCC source have taken steps to limit
the size of the database to less than 2 GBytes even when there is enough
RAM to allow larger database.
Since about Dec. 10, the maximum size of the consensus database has
passed about 2 GBytes.

If your dcc2 has 2 or 3 GBytes while dcc1 has 4 GBytes or more,
the version you are using should try to have those sizes.
By far the best solution is to install the current version (perhaps
by running /var/dcc/libexec/updatedcc), but if you really must use
the old code, you might use something like 
    ./configure --with-max-db-mem=2048
    make install

Vernon Schryver    vjs@rhyolite.com

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