6 More Discussions You Might Find Interesting
1. Infrastructure Monitoring
Dear All,
I am an performance tester. Now i am working in project where we are using linux 2.6.32. Now I got an oppurtunity to learn the monitoring the server. As part of this task i need to do analysis of the Nmon report. I was completely blank in this.
So please suggest me how to start... (0 Replies)
Discussion started by: iamsengu
0 Replies
2. UNIX for Dummies Questions & Answers
Hi,
I am new to the linux kernel development area. I want to know what is the difference between kernel mode stack and user mode stack? Does each process has a user mode stack and a kernel mode stack?? Or Each process has a user mode stack and there is only one kernel mode stack that is shared by... (4 Replies)
Discussion started by: saurabhkoar
4 Replies
3. UNIX for Dummies Questions & Answers
Hey Guys,
Does anyone know how to count the separate amount of words in a text file?
e.g
the 5
and 20
Furthermore does anyone know how to convert whole numbers in decimals?
Thanks (24 Replies)
Discussion started by: John0101
24 Replies
4. Shell Programming and Scripting
:confused:Hi ,
Can someone please advise what is the meaning of metacharacters in below code?
a_PROCESS=${0##*/}
a_DPFX=${a_PROCESS%.*}
a_LPFX="a_DPFX : $$ : "
a_UPFX="Usage: $a_PROCESS"
Regards,
gehlnar (3 Replies)
Discussion started by: gehlnar
3 Replies
5. Programming
helo can u tell me what do you mean by stack winding and stack unwinding
Regards,
Amit (2 Replies)
Discussion started by: amitpansuria
2 Replies
6. Solaris
How can I make analysis for catalina.out (2 Replies)
Discussion started by: Burhan
2 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)