In most of the situations you would simply create a loopback device using "losetup" and mount it using the "-o loopback" options. But if you want to create a loopback file, want to partition it, and finally mount a subpartition, this option can not be used. Let see how you can create partitions inside a loopback image. Creating loopback device 1. First create a file of size around 1GB using "dd" command. # dd if=/dev/zero of=loopbackfile.img bs=100M count=10 10+0 records in 10+0 records … [Read more...] about How to create partitions inside loopback device
Archives for March 2018
How to create virtual block device (loop device/filesystem) in Linux
Linux supports a special block device called the loop device, which maps a normal file onto a virtual block device. This allows for the file to be used as a "virtual file system" inside another file. With Linux it's possible to create a file-system inside a single file. These storage devices are available as device files such as /dev/device_name. Create a file 1. First step is to create a file of desired size. The following command will create a file that is 1 GB in size: # dd if=/dev/zero … [Read more...] about How to create virtual block device (loop device/filesystem) in Linux
How to Move OCR, Vote Disk File, ASM SPILE to new Diskgroup
The goal here is to move OCR, voting disk file and ASM spfile in a Grid Infrastructure with RAC cluster to a new ASM disk group. One example would be that you have created these components in the +DATA diskgroup and you wish to move the OCR, Vote File and ASM spfile to a NORMAL or HIGH redundant diskgroup. Basic steps to move to the new diskgroup are outlined below: Create New diskgroup(CRS) with suitable redundancy for OCR and Voting files. Ensure that the new diskgroup is mounted on all … [Read more...] about How to Move OCR, Vote Disk File, ASM SPILE to new Diskgroup
How to Migrate ASM Disk Groups to another Storage Online [non ASMLIB Devices]
The post explains in detail the exact steps to migrate ASM diskgroups from one storage to another storage without a downtime. This procedure will also work for diskgroups hosting OCR and Votefiles and ASM spfile. Note: These steps are applicable to External, Normal & High redundancy diskgroups. If your plans are replacing the current disks associated to your diskgroups with a new storage, this operation can be accomplished without any downtime, so you can follow the next steps Add the … [Read more...] about How to Migrate ASM Disk Groups to another Storage Online [non ASMLIB Devices]
How To Add New Disk to An Existing Diskgroup on RAC Cluster or Standalone ASM Configuration
You have a ASM diskgroup which is about to be full and you need to add new disk to that disk group. Before adding any disk to the disk group you can perform few validation steps to validate whether the candidate disk(s) is/are in good shape and can be accessed from each node (without harming the existing production diskgroups). Creating the New disk under ASMLib Create the new ASMLIB disks using the “/etc/init.d/oracleasm createdisk” command as root OS user: # /etc/init.d/oracleasm … [Read more...] about How To Add New Disk to An Existing Diskgroup on RAC Cluster or Standalone ASM Configuration
How to Migrate ASM Disk Groups to another Storage Online [When ASMLIB Devices Are Involved]
The post explains in detail the exact steps to migrate ASM diskgroups (when using ASMLIB devices) from one storage to another storage without a downtime. This procedure will also work for diskgroups hosting OCR, Vote files and ASM spfiles. Note: These steps are applicable to External, Normal & High redundancy diskgroups. Creating New ASM disks If you need to migrate and to replace the current ASMLIB disks associated to your diskgroups to a new storage, then you can perform this operation … [Read more...] about How to Migrate ASM Disk Groups to another Storage Online [When ASMLIB Devices Are Involved]
How to move ASM spfile to a different disk group
Question When the ASM was first installed the spfile was placed in the default Disk Group (e.g. +DATA). The requirement now is to move the spfile to a different diskgroup. Method 1 : Using "asmcmd spcopy" Copying the spfile Shown below is an example of moving spfile with the "asmcmd spcopy" utility on Oracle Restart environment. 1. List out the current spfile being used in the database with "asmcmd spget" command. $ asmcmd … [Read more...] about How to move ASM spfile to a different disk group
How To Open A Port In CentOS / RHEL 7
A TCP/IP network connection may be either blocked, dropped, open, or filtered. These actions are generally controlled by the IPtables firewall the system uses and is independent of any process or program that may be listening on a network port. This post will outline the steps to open a port required by a application. For this post example, we will be opening Application Specific (Apache) Port 55555. Server details are as below: # uname -a Linux geeklab 3.10.0-693.17.1.el7.x86_64 #1 SMP Thu … [Read more...] about How To Open A Port In CentOS / RHEL 7
How to use “btrfs device” comamnd to add/delete device to/from btrfs filesystem
Btrfs is an open-source, general-purpose file system for Linux. The name derives from the use of B-trees to store internal file system structures. Different names are used for the file system, including “Butter F S” and “B-tree F S.” Development of Btrfs began at Oracle in 2007, and now a number of companies (including Red Hat, Fujitsu, Intel, SUSE, and many others) are contributing to the development effort. Btrfs is included in the mainline Linux kernel. btrfs device Utilities Use the … [Read more...] about How to use “btrfs device” comamnd to add/delete device to/from btrfs filesystem
How to use “btrfs scrub” command to manage scrubbing on Btrfs file systems
You can initiate a check of the entire file system by triggering a file system scrub job. The scrub job runs in the background by default and scans the entire file system for integrity. It automatically attempts to report and repair any bad blocks that it finds along the way. Instead of going through the entire disk drive, the scrub job deals only with data that is actually allocated. Depending on the allocated disk space, this is much faster than performing an entire surface scan of the … [Read more...] about How to use “btrfs scrub” command to manage scrubbing on Btrfs file systems