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Retract hash algo proposal for the moment

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This commit is contained in:
Jakob Borg
2016-01-12 12:01:07 +01:00
parent e59d845978
commit 4d1c1143c2
2 changed files with 2 additions and 63 deletions
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specs/bep-v1.rst
+2 -10
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@@ -337,7 +337,7 @@ folder Flags field contains the following single bit flags:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Hash |D|P|R|
| Reserved |D|P|R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:Bit 31 ("R", Read Only):
@@ -351,14 +351,6 @@ folder Flags field contains the following single bit flags:
:Bit 29 ("D", Ignore Deletes):
is set for folders that the device will ignore deletes for.
:Bits 25-28 (Hash):
indicates the hash algorithm in use for this folder, as a four bit integer.
The value values are:
- 0: SHA256
- 1: Murmur3-128
- 2-15: Reserved for future usage
The **Options** field contains a list of options that apply to the folder.
Fields (Device Structure)
@@ -912,7 +904,7 @@ directions.
Read Only
~~~~~~~~~
In read only mode, a device does not apply any updates from the cluster,
In read only mode, a device does not apply any updates from the cluster,
but publishes changes of its local folder to the cluster as usual.
The local folder can be seen as a "master copy" that is never affected
by the actions of other cluster devices.
users/hashalgo.rst
-53
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@@ -1,53 +0,0 @@
.. _hashalgo:
Hash Algorithms
===============
.. versionadded:: 0.13.0
Description
-----------
A folder can use one of several available hash algorithms when determining
changes to files. The algorithms have different properties -- see the table
below where the differences between the algorithms are highlighted.
========= ======== ============= ================= ================
Algorithm Speed Delta Changes Efficient Renames Efficient Copies
========= ======== ============= ================= ================
SHA256 Slow Yes Yes **Yes**
Murmur3 **Fast** Yes Yes No
========= ======== ============= ================= ================
Speed:
This affects the speed with which content can be hashed. A "slow"
algorithm requires a lot of CPU power, while a "fast" algorithm does not.
The actual scanning speed may however be limited by the disk's transfer
rate.
Delta Changes:
Indicates whether changes to the contents of a file are transferred
efficiently. "Yes" means that only the changed blocks are transferred,
"no" means the whole file must be resent.
Efficient Renames:
Indicates whether renaming a file on one device results in a renaming
operation on another device ("yes"), or whether the renamed file must be
transferred over the network ("no").
Efficient Copies:
Indicates whether a copy of a file on one device results in a local copy
operation on another device ("yes"), or whether the copy must be
transferred over the network ("no").
Changing the Folder Hash Algorithm
----------------------------------
The hash algorithm can only be set when a folder is added to the
configuration, it can not be changed afterwards. To change the hash algorithm
of a folder it must be removed and then added again with the new hash
algorithm. This necessarily results in a full (slow) rescan of the folder
contents.
The hash algorithm for a given folder must be the same for all devices sharing
that folder.