Retract hash algo proposal for the moment

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
+2 -10
View File
@@ -337,7 +337,7 @@ folder Flags field contains the following single bit flags:
0 1 2 3 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 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): :Bit 31 ("R", Read Only):
@@ -351,14 +351,6 @@ folder Flags field contains the following single bit flags:
:Bit 29 ("D", Ignore Deletes): :Bit 29 ("D", Ignore Deletes):
is set for folders that the device will ignore deletes for. 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. The **Options** field contains a list of options that apply to the folder.
Fields (Device Structure) Fields (Device Structure)
@@ -912,7 +904,7 @@ directions.
Read Only 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. 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 The local folder can be seen as a "master copy" that is never affected
by the actions of other cluster devices. by the actions of other cluster devices.
-53
View File
@@ -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.