-syncer
-======
+# syncer
Fast stateful file/disk data syncer.
-#### Description
+WARNING: I advise you to use ZFS and its native send/recv commands.
+I abandoned that project because of that.
-The maain purpose of this utility is fast data synchronizing between two
-hard drives: one is fast (SSD, SATA HDD), another is connected through
-slow USB interface. Task is to lower amounts of data needed to be
-transferred.
+## Description
+
+The main purpose of this utility is fast data synchronization between
+two hard drives: one is fast (SSD, SATA HDD), another is connected
+through slow USB interface. Target is to lower data amounts needed to
+be transferred.
This utility is stateful: it keeps precomputed data hashes in separate
-statefile and use it to determine if we need to update block of data.
+statefile and uses it to determine if we need to update block of data.
-```
-# sync from very fast SSD to slow USB connected HDD
-% ./syncer -src /dev/ada0 -dst /dev/da0 -state state.bin
-[%%%%%%]
-# all blocks were transferred to da0
-```
+ # sync from very fast SSD to slow USB connected HDD
+ % ./syncer -src /dev/ada0 -dst /dev/da0 -state state.bin
+ [%%%%%%]
+ # all blocks were transferred to da0
Now we have statefile containing cryptographic hashes of the blocks from
source and copy of all read data in destination. Now if we run it again:
-```
-% ./syncer -src /dev/ada0 -dst /dev/da0 -state state.bin
-[....%.]
-# only one block was transferred to da0
-```
+ % ./syncer -src /dev/ada0 -dst /dev/da0 -state state.bin
+ [....%.]
+ # only one block was transferred to da0
Only one modified block was transferred during this session. We read all
data from source again, compute hashes and understand what was updated
syncer is free software: see the file COPYING for copying conditions.
-### Installation
+## Installation
-```
-% go get github.com/dchest/blake2b
-% go build
-# syncer executable file should be in current directory
-```
+ % mkdir -p src
+ % git clone git://git.cypherpunks.ru/syncer.git src/syncer
+ % export GOPATH=$(pwd)
+ % go get github.com/dchest/blake2b
+ % go build syncer # syncer executable file should be in current directory
-### Statefile Format
+## Statefile Format
-`SRC_SIZE || BLK_SIZE || HASH0 || HASH1 || ...`
+ SRC_SIZE || BLK_SIZE || HASH0 || HASH1 || ...
-SRC_SIZE contains size of the source, when it was firstly read. BLK_SIZE
-is the blocksize used. Both is 64-bit big-endian unsigned integers. If
-either size or blocksize differs, then syncer will deny using that
-statefile as a precaution. HASHx is BLAKE2b-512 hash output, 64 bytes.
+`SRC_SIZE` contains size of the source, when it was initially read.
+`BLK_SIZE` is the blocksize used. Both are 64-bit big-endian unsigned
+integers. If either size or blocksize differs, then syncer will deny
+using that statefile as a precaution. `HASHx` is BLAKE2b-512 hash
+output, 64 bytes.