I hacked my TIVO a few months ago. I made a computer specifically for this, but I only used a UNIX boot disk to get all the TIVO goodies to work. I am intersted in getting some version of UNIX on this machine and getting it onto my network. I only want to do some simple file transfers, maybe... (1 Reply)
I coudln't think of another topic to post this under as the OS on the system is XP pro.
Ok here is the go.
I'm upgrdaing a mates computer. A AMD 1200Mhz and well it wouldn't boot from the CD to do a fresh install (By upgrade I mean OS with complete new install). So I opened up the box and... (4 Replies)
Hi ,
This is a pretty simple sed command i found when i was checking out one of the codes of my colleague .
sed -e 's/\*.*\) \(\ <1*e\ >\) \(*.*\)/\2/'
When i tried this on a few text files it was displaying the entire line. If this was to display entire line why sweat out on a sed . Does... (3 Replies)
Hi,
I am trying to write a script to do monitoring kind of stuff,
requirement - when a server is given a start it updates a file called server.log, I need to keep on grepping the word "Running" and as soon as it comes , script should be exited with the message , "Server came up... (2 Replies)
HI all...
(Apologies for any typos.)
To add to Neo's Arduino subject matter I have decided to upload this in ".zip" format.
Ignore "*.info" files these are AMIGA icons only and also the "HAM" drawer as these are photos in ancient AMIGA HAM modes.
I have noticed that there are current... (6 Replies)
Discussion started by: wisecracker
6 Replies
LEARN ABOUT DEBIAN
bup-margin
bup-margin(1) General Commands Manual bup-margin(1)NAME
bup-margin - figure out your deduplication safety margin
SYNOPSIS
bup margin [options...]
DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two
entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids.
For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit
hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by
its first 46 bits.
The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits,
that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits
with far fewer objects.
If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if
you're getting dangerously close to 160 bits.
OPTIONS --predict
Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer
from the guess. This is potentially useful for tuning an interpolation search algorithm.
--ignore-midx
don't use .midx files, use only .idx files. This is only really useful when used with --predict.
EXAMPLE
$ bup margin
Reading indexes: 100.00% (1612581/1612581), done.
40
40 matching prefix bits
1.94 bits per doubling
120 bits (61.86 doublings) remaining
4.19338e+18 times larger is possible
Everyone on earth could have 625878182 data sets
like yours, all in one repository, and we would
expect 1 object collision.
$ bup margin --predict
PackIdxList: using 1 index.
Reading indexes: 100.00% (1612581/1612581), done.
915 of 1612581 (0.057%)
SEE ALSO bup-midx(1), bup-save(1)BUP
Part of the bup(1) suite.
AUTHORS
Avery Pennarun <apenwarr@gmail.com>.
Bup unknown-bup-margin(1)