How to run a pruning node with leveldb

Pruning nodes use a lightweight database to store address histories.
Only unspent coins are kept in that database; spent outputs are
pruned.


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1. patch and compile bitcoind.

Install version 0.8 or equivalent.
Patch it with the patch distributed with Electrum.

Note: Even though Electrum's database uses pruning, you cannot use it
with a pruning bitcoind. A full bitcoin node is required in order to
know for each address if it has been used. Pruning occurs only at the
level of the Electrum database.

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2. Install python-leveldb: 

sudo apt-get install python-leveldb

alternatively build yourself, see
http://code.google.com/p/py-leveldb/ 
and
http://peter-hoffmann.com/2011/installation-leveldb-ubuntu-python.html
make sure you have libtool, automake and pkg-config

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3. edit /etc/electrum.conf : 

[server]
backend = leveldb

[leveldb]
path = /path/to/your/database
pruning_limit = 10

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4. catch up with the blockchain.

In order to speed up the initial catch_up phase, it is recommended to
locate your database in shared memory:

 path = /run/shm/electrum_db

Once your server has finished catching up, copy your database to disk
and update the path in /etc/electrum.conf

During the catch_up phase, you can interrupt the server with Ctrl-C;
it will safely write the current status in the database and exit.

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5. enjoy!

Once the server is synchronized, it will listen to ports, and the
normal way to stop it is to type: ./server.py stop

Other commands are available: 

./server info   : view connections
./server load   : view the size of the queue


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Troubleshooting:

* if your server or bitcoind is killed because is uses too much
memory, configure bitcoind to limit the number of connections

* if you see "Too many open files" errors, you may need to increase
your user's File Descriptors limit. For this, see
http://www.cyberciti.biz/faq/linux-increase-the-maximum-number-of-open-files/