Hi ,
I have a question about performance of writing into a file.
Will it take more time to open a file, write a line into the file and close the file
if the file size grows bigger and bigger??
Say, I have two files of sizes 100KB and 20MB.
Will it take more time to open/write a... (1 Reply)
About 4 years ago I wrote this tool inspired by Rob Urban's collect tool for DEC's Tru64 Unix. What makes this tool as different as collect was in its day is its ability to run at a low overhead and collect tons of stuff. I've expanded the general concept and even include data not available in... (0 Replies)
Hi All
I am reading a huge file of size 2GB atleast. I am reading each line and cutting certain columns and writing it to another file.
Here is the logic.
int main()
{
string u_line;
string Char_List;
string u_file;
int line_pos;
string temp_form_u_file;
... (10 Replies)
hi all,
I was able to do a script to gather a few files and sort them.
here it is:
#!/usr/bin/ksh
ls *mainFile* |cut -c20-21 | sort > temp
set -A line_array
i=0
file_name='temp'
while read file_line
do
line_array=${file_line}
let i=${i}+1 (5 Replies)
Hello,
I'm running a script on AIX to process lines in a file. I need to enclose the second column in quotation marks and write each line to a new file. I've come up with the following:
#!/bin/ksh
filename=$1
exec >> $filename.new
cat $filename | while read LINE
do
echo $LINE | awk... (2 Replies)
Hello Gurus,
We are facing some performance issue in UNIX. If someone had faced such kind of issue in past please provide your suggestions on this .
Problem Definition:
/Few of load processes of our Finance Application are facing issue in UNIX when they uses a shell script having below... (19 Replies)
Hi guys,
what is the relation between I/O performance and file systems.
I have a file systems called /dcs/data01 which is having 4Tb size.
According our application we can split the file system like
dcs/data01 -> 1Tb
dcs/data02 -> 1Tb
dcs/data03 -> 1Tb
dcs/data04 -> 1Tb
do you... (4 Replies)
Please, I need help tuning my script. It works but it's too slow.
The code reads an acivity log file with 50.000 - 100.000 lines and filters error messages from it. The data in the actlog file look similar to this:
02/08/2011 00:25:01,ANR2034E QUERY MOUNT: No match found using this criteria.... (5 Replies)
Hello all -
I am to this forum and fairly new in learning unix and finding some difficulty in preparing a small shell script. I am trying to make script to sort all the files given by user as input (either the exact full name of the file or say the files matching the criteria like all files... (3 Replies)
Hi Experts,
I have a filelist collected from another server , now want to sort the output using date/time stamp filed.
- Filed 6, 7,8 are showing the date/time/stamp.
Here is the input:
#----------------------------------------------------------------------
-rw------- 1 root ... (3 Replies)
Discussion started by: rveri
3 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)