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Linux Scan for New Scsi Device to Detect New Lun Without Reboot

This will scan the scsi host and there is no need to reboot to make devices (luns) visible. echo "- - -" > /sys/class/scsi_host/host#/scan Verify fdisk -l tail -f /var/log/message Replace host# with actual value such as host0. You can find scsi_host value using the following command: # ls /sys/class/scsi_host Now, type the following to […]

March 20, 2011 | By
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Linux Install Network Or Ethernet Card In Linux

How to install a Network card in linux. There are different ways of installing a network card in linux- and that too depending on the linux distribution that you are using. I will explain each one of these methods here. 1) The Manual method First open the computer case and insert the network card into […]

March 20, 2011 | By
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Can dd Command Used To Wipe Data? Examples

dd is a common Unix program whose primary purpose is the low-level copying and conversion of raw data. You can use this command backup whole hard drives, create a large file filled with only zeros, create and modify image files at specific points and even do conversions to upper case. dd command can strip headers, […]

March 20, 2011 | By
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How To Use Linux Kill Command

The word kill itself shows its clear meaning and purpose. In Linux, kill command is used for terminating the process. The command kill sends the specified signal to the specified process or the process group. First we need find PID of the process, so that we can terminate the process. In our example, we will […]

March 20, 2011 | By
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Creating Logical Volume On Existing Volume Group In Linux

Create logical volume on existing VG (Volume group) First make sure you have proper space to create new lv. From the below output, you can see there is enough space to have a new lv: #vgdisplay /dev/vg01 --- Volume group --- VG Name vg01 VG Access read/write VG Status available/resizable VG # 0 MAX LV […]

March 20, 2011 | By
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How To Ssh Server Using Private Key In Putty

How to ssh server using openssh software Generating OpenSSH private and public keys pair. To use public key authentication, the first step is to generate a pair of private and public keys on the Linux side. I would assume that you login as a user called "toylet". 1. Login Linux as user "toylet". You could […]

March 14, 2011 | By
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CPU Bottleneck - How To Use Vmstat, Mpstat and SAR Commands

One of the main functions the kernel or Operating System is Memory Management. When process try to access physical memory, if physical memory not free, than kernel move the inactive processes to virtual memory then it is called Paging. To know which process is using physical memory and virtual memory, we use vmstat, mpstat, sar commands. […]

March 14, 2011 | By
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How Linux Administrator Monitor High Cpu Utilization

CPU is core part the system and processes all the task. There are many methods to check the CPU performance on linux system. Most commonly used commands are top, ps, sar, iostat, mpstat and to check the daily CPU performance. Whenever CPU is busy in processing a particular task, it becomes unavailable to other processes. […]

March 14, 2011 | By
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Difference Between NFS Soft And Hard Mount With Example

Using NFS protocol, the NFS client can mount the filesystem existing on a NFS server, just like a local filesystem. For example, you will be able to mount “/home” directory of host.nfs_server.com to your client machine as follows: # mount host.nfs_server.com:/home /techhome The directory “/techhome” should be created in your machine to hold the NFS […]

March 9, 2011 | By
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How To Find Un Allocated Space On Linux

Using only fdisk, the "start" and "end" columns in your 'fdisk -l' output are the start and end cylinders. From the header of your 'fdisk -l' output, you can also see how many cylinders the disk has and how many bytes a cylinder represents. fdisk -l /dev/cciss/c0d0 Disk /dev/cciss/c0d0: 72.8 GB, 72833679360 bytes 255 heads, […]

March 9, 2011 | By
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Linux Samba Share Accessing And Mounting

Samba is a service in Linux that provides seamless file and print service to SMB/CIFS clients. One of the main feature of samba is that it allows interoperability between Linux/Unix servers and Window-based clients. In general, you can share resource-like files and printers over network between Unix to Unix as well as Unix to Windows. In […]

March 9, 2011 | By
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Difference between FC SAN, ISCSI SAN, DAS and NAS

SAN Advantages 1) Share storage among different application servers. 2) Data is stored at a block level. 3) Physical elements of the SAN (servers, switches, storage arrays, etc.) are connected with Fibre Channel. 4) SAN is both scalability and flexibility. 5) Storage can be added without disrupting the applications and the different types of storage […]

March 8, 2011 | By
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Create, Format, Mount Filesystems in Linux

A filesystem is an organization of data and metadata on storage device. You can also say it as organizing data in systematic manner. Linux filesystem interface is implemented as a layer architecture. Today unix-like operating system contains only files. If you want to access any files in unix-like OS, filesystem has to be mounted where […]

February 25, 2011 | By
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Shared Memory Settings In Linux With Examples

Shared memory is the memory that may be accessed by multiple processes; i.e. a memory region that can be shared between different processes and a better way of passing data between two processes. Shared memory is the fastest form of Inter Process Communication which is currently available. Assume that the program will create a memory […]

February 25, 2011 | By
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