This is second post from the ISCSI administration series ( you can refer the first post here RHEL 6 – ISCSI Administration Series – Configuring ISCSI Server and Client ) . In this post, I will be showing you an hands-on exercise to expand a ISCSI LUN which is already configured from the client and actively in use.
Before going for Actual Task, Just want to show my current configuration both from server side and client side:
In this post I am explaining about the procedure to add 20G to /applocal volume configured in Virtual Linux Machine. A new Disk sdb is partitioned as sdb1 and it was allocated to LVM from outside, and after the reboot the disk is visible to Linux as /dev/sdb.
The procedure to increase the /applocal involves following steps.
1. Verify the hard disk information from linux
[root@Gurkulindia-VM-Linux ~]# fdisk -l
Disk /dev/sda: 11.8 GB, 11811160064 bytes
255 heads, 63 sectors/track, 1435 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 102400 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 14 1436 11427840 8e Linux LVM
Partition 2 does not end on cylinder boundary.
Disk /dev/sdb: 42.9 GB, 42949672960 bytes <== New disk can be seen
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964761 83 Linux <== Currently having single partition of Linux
In this doc I am trying to present base for Linux Filesystem. I tried to cover Theoratical and Pratical portition where-ever it is necessary.
What is Filesystem
In simple term you can say a FS is a medium to access your files/directories in any Unix Flavour. In Unix each and every thing is File or Directory. In order to standardize Files or Directories structure Filesystem are used.
Now in depth you can say a FS is a portion of your harddisk (or complete harddisk) which is used to create files and directories which are world-wide accessiable. Full Story
Device-mapper is a very important component of Linux 2.6 kernel. It is used for many critical storage related applications, such as LVM2, Linux native multipath tool device-mapper-multipath, device-mapper software RAID, etc. A solid understanding of device-mapper helps system administrators to investigate various kinds of issues with these applications.
In the Linux kernel, the device-mapper is a generic framework to map one block device into another. It is not just for LVM2. By using device-mapper, the kernel provides general services to dm-multipath, LVM2 and EVMS, device-mapper software RAIDs, dm-crypt disk encryption and offers additional features such as file system snapshots. Full Story
Below procedure can be used to identify the hard disk errors in linux operating system.
Execute the following command to identify the available disk configuration
# /bin/more /proc/scsi/scsi
Output will include all the currently available disks to the linux, and the output vary depending on platform model and configuration, but will be similar to the following: Full Story
In Enterprise environment Linux operating systems were installed on various X86 ( HP / SUN ) models of hardware, and most of the times we dont use software Raid to mirror the Operating system harddisks, and we rely on the hardware RAID.
Below tips will be useful to identify the whether the linux OS are under hardware RAID or not. If OS disks are under control of HARDWARE RAID, then what type of Hardware RAID it is using.
About Author : My name is Ramkumar Ramadevu ( Ramdev ). I have started writing about enterprise unix system administration since 2009 just for my own knowledge reference, and then later I have made this site available for everyone, for better purpose. ... read more