Autoprune release notes included

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mrbandrews 2015-05-26 15:32:25 -04:00
parent 165e323d85
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(note: this is a temporary file, to be added-to by anybody, and moved to
release-notes at release time)
Notable changes
===============
Block file pruning
----------------------
This release supports running a fully validating node without maintaining a copy
of the raw block and undo data on disk. To recap, there are four types of data
related to the blockchain in the bitcoin system: the raw blocks as received over
the network (blk???.dat), the undo data (rev???.dat), the block index and the
UTXO set (both LevelDB databases). The databases are built from the raw data.
Block pruning allows Bitcoin Core to delete the raw block and undo data once
it's been validated and used to build the databases. At that point, the raw data
is used only to relay blocks to other nodes, to handle reorganizations, to look
up old transactions (if -txindex is enabled or via the RPC/REST interfaces), or
for rescanning the wallet. The block index continues to hold the metadata about
all blocks in the blockchain.
The user specifies how much space to allot for block & undo files. The minimum
allowed is 550MB. Note that this is in addition to whatever is required for the
block index and UTXO databases. The minimum was chosen so that Bitcoin Core will
be able to maintain at least 288 blocks on disk (two days worth of blocks at 10
minutes per block). In rare instances it is possible that the amount of space
used will exceed the pruning target in order to keep the required last 288
blocks on disk.
Block pruning works during initial sync in the same way as during steady state,
by deleting block files "as you go" whenever disk space is allocated. Thus, if
the user specifies 550MB, once that level is reached the program will begin
deleting the oldest block and undo files, while continuing to download the
blockchain.
For now, block pruning disables block relay. In the future, nodes with block
pruning will at a minimum relay "new" blocks, meaning blocks that extend their
active chain.
Block pruning is currently incompatible with running a wallet due to the fact
that block data is used for rescanning the wallet and importing keys or
addresses (which require a rescan.) However, running the wallet with block
pruning will be supported in the near future, subject to those limitations.
Block pruning is also incompatible with -txindex and will automatically disable
it.
Once you have pruned blocks, going back to unpruned state requires
re-downloading the entire blockchain. To do this, re-start the node with
-reindex. Note also that any problem that would cause a user to reindex (e.g.,
disk corruption) will cause a pruned node to redownload the entire blockchain.
Finally, note that when a pruned node reindexes, it will delete any blk???.dat
and rev???.dat files in the data directory prior to restarting the download.
To enable block pruning on the command line:
- `-prune=N`: where N is the number of MB to allot for raw block & undo data.
Modified RPC calls:
- `getblockchaininfo` now includes whether we are in pruned mode or not.
- `getblock` will check if the block's data has been pruned and if so, return an
error.
- `getrawtransaction` will no longer be able to locate a transaction that has a
UTXO but where its block file has been pruned.
Pruning is disabled by default.
0.11.0 Change log
=================