How do I check the performance of a hard drive including the read and write speed on a Linux operating systems?

dd command

dd is a command-line utility for Unix and Unix-like operating systems whose primary purpose is to convert and copy files.

In this tutorial I will show you how to use the dd command to test disk I/O performance.

Open a shell prompt or login to a remote server via ssh and type the following command

# dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync

Sample outputs

16384+0 records in
16384+0 records out
1073741824 bytes (1.1 GB) copied, 5.00633 s, 214 MB/s

Test on device

ATA device, with non-removable media
	Model Number:       SAMSUNG MZ7WD120HCFV-00003              
	Serial Number:      S1FZNYAG402762      
	Firmware Revision:  DXM9203Q
	Transport:          Serial, ATA8-AST, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0

Understanding dd command options

if=/dev/zero: The name of the input file you want dd the read from.
of=test: The name of the output file you want dd write the input file to.
bs=64k (block-size) : Set the size of the block you want dd to use.
count=16k (number of blocks): The number of blocks you want dd to read.
conv=fdatasync: The flag conv=fdatasync tells dd to sync the write to disk before it exits. Without this flag, dd will perform the write but some of it will remain in memory, not giving you an accurate picture of the true write performance of the disk.

The post How To Test Disk I/O Performance With dd Command appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

A master boot record (MBR) is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk. MBRs are usually placed on storage devices intended for use with IBM PC-compatible systems.

MBR Total Size

446 + 64 + 2 = 512

Where,
446 bytes – Bootstrap.
64 bytes – Partition table.
2 bytes – Signature.

Backup MBR

Linux or Unix provides “dd” tool to backup any file. Usually, you must be “root” so that you can use it.

# dd if=/dev/sda of=/backup/mbr_sda.bak bs=512 count=1

Above command will copy 512 bytes (MBR) from sda to mbr_sda.bak

Restore MBR

To restore the MBR and partition table, type the following command

# dd if=/backup/mbr_sda.bak of=/dev/hda bs=512 count=1

To restore the MBR, type the following command

# dd if=/backup/mbr_sda.bak of=/dev/hda bs=446 count=1

The post How To Backup & Restore Master Boot Record (MBR) In Linux appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

If you need additional swap space to improve your system performance. You have two different ways: add/upgrade a swap partition or create a swap file. But changing the size or create a new swap partition is not easy, the best solution is to create a new swap file. This articles help you add/create swap file very quickly.

Creating swap file on Linux

Login as root and type the following command to create 512MB swap file

[root@lifelinux ~]# dd if=/dev/zero of=/swapfile bs=1024 count=524288

Where,
if=/dev/zero: read from /dev/zero instead of stdin
of=/swapfile: write to /swapfile instead of stdout
bs=1024: blocksize = 1024 bytes
count=524288: number of blocks are 524288

Setup the swap file with the command: mkswap. Type following command to setup your swap file:

[root@lifelinux ~]# mkswap /swapfile

To enable the swap file immediately but not automatically at boot time

[root@lifelinux ~]# swapon /swapfile

To activate the new swap file automatically at the boot, you need to edit the file /etc/fstab, enter

[root@lifelinux ~]# vi /etc/fstab

Add the following line at end of the file

/swapfile         swap             swap        defaults         0   0

To verify the swap file is working fine with these commands:

[root@lifelinux ~]# free -m

Or

[root@lifelinux ~]# cat /proc/swaps

Recommended size of linux swap

1 GB RAM —> 2 GB of Swap file
2 GB RAM —> 4 GB of Swap file
4 GB RAM —> 8 GB of Swap file
8 GB RAM —> 12 GB of Swap file
16 GB RAM —> 24 GB of Swap file
32 GB RAM —> 32 GB of Swap file

The post How To Add/Create Swap File appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

While having a large hard drive is good for storing lots of data, it is also important for your computer to have a fast hard drive. Faster hard drives help your computer run more smoothly. You can use the hdparm tool or dd command to determine your disk speeds from the Linux command line.

List Hard Drives

Open a terminal or go to a command line on your Linux system. As root, run the command:

[root@server2 ~]# fdisk -l

Sample outputs:

Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          13      104391   83  Linux
/dev/sda2              14         274     2096482+  83  Linux
/dev/sda3             275         535     2096482+  82  Linux swap / Solaris
/dev/sda4             536       30400   239890612+   5  Extended
/dev/sda5             536       30400   239890581   83  Linux

Disk /dev/sdb: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1          13      104391   83  Linux
/dev/sdb2              14         274     2096482+  83  Linux
/dev/sdb3             275         535     2096482+  82  Linux swap / Solaris
/dev/sdb4             536       30400   239890612+   5  Extended
/dev/sdb5             536       30400   239890581   83  Linux

hdparm command

You can use the hdparm command to check hard disk speed. It provides a command line interface to various hard disk ioctls supported by the stock Linux ATA/IDE/SATA device driver subsystem. Login as the root and enter the following command:

[root@server2 ~]# hdparm -tT /dev/sda

Sample outputs:

/dev/sda:
 Timing cached reads:   29084 MB in  2.00 seconds = 14574.71 MB/sec
 Timing buffered disk reads:  308 MB in  3.01 seconds = 102.36 MB/sec

Note:
-t :perform device read timings
-T :perform cache read timings
/dev/sda : Hard disk device file

dd Command

You can use the dd command as follows to get speed info too:

[root@server2 ~]# dd if=/dev/zero of=/tmp/test.img bs=8k count=256k
[root@server2 ~]# rm /tmp/test.img

Sample outputs:

dd: writing `/tmp/test.img': No space left on device
210779+0 records in
210778+0 records out
1726697472 bytes (1.7 GB) copied, 22.3398 seconds, 77.3 MB/s

The post Linux Hard Disk Speed Tests appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

If you want to delete all data contained in your hard drive so that you render it empty in case you want to sell it or for any other reasons, you need to follow these steps:

1. Turn on your computer and boot from Debian Live CD or any of its variants (Debian, Ubuntu, Xubuntu, Edubuntu, Ubuntulite, Fluxbuntu, etc.).
2. In the terminal, run the command given below to disable the swap partition:

sudo swapoff

Note: If you don’t execute this command, some data might remain on your hard drive.

3. Now you have to run the command listed below to zero out your hard drive:

sudo dd if=/dev/zero of=/dev/sda

The formatting process might take a long time to finish, this depends on the size of your hard disk. To view remaining time, you have to run this command:

sudo killall -USR1 dd

Upon running the command listed above, you will be shown the disk space “cleaned” in GB.

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