Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Difference between buffered disk reads and cached reads? Post 302538491 by pinga123 on Wednesday 13th of July 2011 06:23:02 AM
Old 07-13-2011
Difference between buffered disk reads and cached reads?

I was analyzing the Disk read using hdparm utility.

This is what i got as a result.

Code:
# hdparm -t /dev/sda

/dev/sda:
 Timing buffered disk reads:  108 MB in  3.04 seconds =  35.51 MB/sec

Code:
# hdparm -T /dev/sda

/dev/sda:
 Timing cached reads:   3496 MB in  1.99 seconds = 1756.56 MB/sec

I m not sure what does Cache read and buffered disk read mean.

Please share your hdparm output for comparison purpose.
 

10 More Discussions You Might Find Interesting

1. Programming

scanf doesn´t reads spaces ???

hi all i have a program in C (Unix Solaris 5.7) and i want to read a string from keyboard, but the "scanf" doesn´t reads spaces. example: .... char name; .... printf("Enter your name: "); scanf("%s",&name); printf ("Your name is: %s", name); and if i write Kevin Costner ... (4 Replies)
Discussion started by: DebianJ
4 Replies

2. Shell Programming and Scripting

identify the unix processes performing high disk i/o reads and writes

I would like to write shell/perl script which identifies the top unix processes that are performing high disk I/O's or/and writes If any one knows the solution please help me? -Swamy (0 Replies)
Discussion started by: avsswamy
0 Replies

3. UNIX for Advanced & Expert Users

identify the unix process performing high disk i/o reads and writes

Guys, Is there any UNIX command that captures the 'Unix process which is performing high disk I/O reads and writes'. can you help me in this? -Swamy (6 Replies)
Discussion started by: avsswamy
6 Replies

4. Filesystems, Disks and Memory

Does vmstat -d give a count of actual physical writes/reads done to/from hard disk?

Hi, I am trying to find the reliability of 'vmstat -d' for showing the actual physical writes on sectors on hard disk. Can anyone please tell me if the numbers in the "sectors" field under "read" or "write" headers show a count of the actual write commands sent to disk from the low level... (2 Replies)
Discussion started by: jake24
2 Replies

5. Shell Programming and Scripting

Illumina reads remove duplicate...

After I using the search tool, I still can't find a solution that was related with my trouble. My input file: @HWI-ABC123_30DFGGDA:1:100:3:1234 ACGTAGTACCCGGGTTTTTTTTTAAAAAAA +HWI-ABC123_30DFGGDA:1:100:3:1234 hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh @HWI-ABC555_30DFGGDA:1:100:3:1234... (14 Replies)
Discussion started by: patrick87
14 Replies

6. Shell Programming and Scripting

While loop in unix reads only first line

Hi, I am in need of help on reading through a file(servernames.dat) which has a list of server names, while it reads each file name it has to connect to that server and run another script, once it has executed the script on one server, it has to go back to the list of servernames to get the next... (5 Replies)
Discussion started by: yohasini
5 Replies

7. Linux

Dealing with a really high amount of reads merged

I'm trying to performance tune the I/O of my web server, which is at 41.1% reads merged (If my math is correct), which seems a tad high to just be going along with the defaults. Will modifying read_ahead_kb affect the value of "reads merged" in diskstats? If not, what's a good way of tracking... (2 Replies)
Discussion started by: thmnetwork
2 Replies

8. Shell Programming and Scripting

mapped reads using samtools flagstat options

Hey guys, Does anyone know how to calculate total number of mapped reads for a certain region of a bam file using samtools flagstat? I know to use flagstat for the whole bam file. but for a specific region of it... is there an option? Tnx ---------- Post updated at 12:27 PM ----------... (1 Reply)
Discussion started by: @man
1 Replies

9. UNIX for Dummies Questions & Answers

Sudo reads password from a .cfg file

cleanwork /saswork removes sas orphanded processes in the saswork directory. Subdirectories under sasem are sas94, sas92 and sasworks . I am getting the following error messages: 1. '/usr/bin/sudo -S apt-get update <~/opt/SiM/pos/ps/db_auth.cfg... (4 Replies)
Discussion started by: dellanicholson
4 Replies

10. Shell Programming and Scripting

Shell Script that reads a file

I have below script to read a file line by line. How can I ensure that the loop will stop after last line. #!/bin/bash while read -r mod ver tarball; do echo $mod done < taskfile.txt (4 Replies)
Discussion started by: aderamos12
4 Replies
PARTX(8)						       System Administration							  PARTX(8)

NAME
partx - tell the Linux kernel about the presence and numbering of on-disk partitions SYNOPSIS
partx [-a|-d|-s] [-t TYPE] [-n M:N] [-] disk partx [-a|-d|-s] [-t TYPE] partition [disk] DESCRIPTION
Given a device or disk-image, partx tries to parse the partition table and list its contents. It optionally adds or removes partitions. The disk argument is optional when a partition argument is provided. To force scanning a partition as if it were a whole disk (for example to list nested subpartitions), use the argument "-". For example: partx --show - /dev/sda3 This will see sda3 as a whole-disk rather than a partition. This is not an fdisk program -- adding and removing partitions does not change the disk, it just tells the kernel about the presence and numbering of on-disk partitions. OPTIONS
-a, --add Add the specified partitions, or read the disk and add all partitions. -b, --bytes Print the SIZE column in bytes rather than in human-readable format. -d, --delete Delete the specified partitions or all partitions. -g, --noheadings Do not print a header line. -l, --list List the partitions. Note that all numbers are in 512-byte sectors. This output format is DEPRECATED in favour of --show. Don't use it in newly written scripts. -o, --output list Define the output columns to use for --show and --raw output. If no output arrangement is specified, then a default set is used. Use --help to get list of all supported columns. -r, --raw Use the raw output format. -s, --show List the partitions. All numbers (except SIZE) are in 512-byte sectors. The output columns can be rearranged with the --output option. -t, --type type Specify the partition table type -- aix, bsd, dos, gpt, mac, minix, sgi, solaris_x86, sun, ultrix or unixware. -n, --nr M:N Specify the range of partitions. For backward compatibility also the format <M-N> is supported. The range may contain negative numbers, for example "--nr :-1" means the last partition, and "--nr -2:-1" means the last two partitions. Supported range specifi- cations are: <M> Specifies just one partition (e.g. --nr 3). <M:> Specifies lower limit only (e.g. --nr 2:). <:N> Specifies upper limit only (e.g. --nr :4). <M:N> or <M-N> Specifies lower and upper limits (e.g. --nr 2:4). EXAMPLES
partx --show /dev/sdb3 partx --show --nr 3 /dev/sdb partx --show /dev/sdb3 /dev/sdb All three commands list partition 3 of /dev/sdb. partx --show - /dev/sdb3 Lists all subpartitions on /dev/sdb3 (the device is used as whole-disk). partx -o START -g --nr 3 /dev/sdb Prints the start sector of partition 5 on /dev/sda without header. partx -o SECTORS,SIZE /dev/sda5 /dev/sda Lists the length in sectors and human-readable size of partition 5 on /dev/sda. partx --add --nr 3:5 /dev/sdd Adds all available partitions from 3 to 5 (inclusive) on /dev/sdd. partx -d --nr :-1 /dev/sdd Removes the last partition on /dev/sdd. SEE ALSO
addpart(8), delpart(8), fdisk(8), parted(8), partprobe(8) AUTHORS
Davidlohr Bueso <dave@gnu.org> Karel Zak <kzak@redhat.com> The original version was written by Andries E. Brouwer <aeb@cwi.nl>. AVAILABILITY
The partx command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/. util-linux February 2011 PARTX(8)
All times are GMT -4. The time now is 06:38 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy