Showing posts from October, 2013

Measure Hard Disk Data Transfer Speed

Measure Hard Disk Data Transfer Speed Login as the root and enter the following command: $ sudo hdparm -tT /dev/sda OR $ sudo hdparm -tT /dev/hda Sample outputs:   /dev/sda: Timing cached reads: 7864 MB in 2.00 seconds = 3935.41 MB/sec Timing buffered disk reads: 204 MB in 3.00 seconds = 67.98 MB/sec For meaningful results, this operation should be repeated 2-3 times . This displays the speed of reading directly from the Linux buffer cache without disk access. This measurement is essentially an indication of the throughput of the processor, cache, and memory of the system under test.  Here is a for loop example, to run test 3 time in a row: for i in 1 2 3; do hdparm -tT /dev/hda; done Where, -t :perform device read timings -T : perform cache read timings /dev/sda : Hard disk device file To find out SATA hard disk speed, enter: sudo hdparm -I /dev/sda | grep -i speed Output: * Gen1 signaling speed (1.5Gb/s) * Gen2 signalin

Wake on Lan in Centos 6

      Start a computer from a remote machine by Wake on Lan. [1]     Configuration of the computer you'd like to turn on from remote machine.  yum -y install ethtool ethtool -s eth0 wol g or: vi /etc/sysconfig/network-scripts/ifcfg-eth0 # add at the last line ETHTOOL_OPTS="wol g " check for MAC ifconfig eth0 | grep HWaddr | awk '{print $5}' 00:22:68:5E:34:06 # take a memo shutdown -h now [2]     Operation on the computer at a remore place. yum -y install net-tools # ether-wake [MAC address of the computer you'd like to turn on] ether-wake 00:22:68:5E:34:06  # send magic packets ***correction If have more than one interface need to specify it, for example: ether-wake -i eth0 00:22:68:5E:34:06 found at:

How to Increase the size of a Linux LVM by expanding the virtual machine disk

How to Increase the size of a Linux LVM by expanding the virtual machine disk This post will cover how to increase the disk space for a VMware virtual machine running Linux that is using logical volume manager (LVM). Firstly we will be increasing the size of the actual disk on the VMware virtual machine, so at the hardware level – this is the VM’s .vmdk file. Once this is complete we will get into the virtual machine and make the necessary changes through the operating system in order to take advantage of the additional space that has been provided by the hard drive being extended. This will involve creating a new partition with the new space, expanding the volume group and logical group, then finally resizing the file system. As there are a number of different ways to increase disk space I have also posted some different methods here: Use GParted to increase disk size of a Linux native partition – In this article the virtual disk is expanded, however there is