Internet Small Computer System Interface (iSCSI) is an IP-based standard for connecting storage devices. iSCSI uses IP networks to encapsulate SCSI commands, allowing data to be transferred over long distances. iSCSI provides shared storage among a number of client systems. Storage devices are attached to servers (targets). Client systems (initiators) access the remote storage devices […]
Archives for February 2018
CentOS / RHEL 6,7 : How to delete an iSCSI Target on the initiator (iSCSI client)
Internet Small Computer System Interface (iSCSI) is an IP-based standard for connecting storage devices. iSCSI uses IP networks to encapsulate SCSI commands, allowing data to be transferred over long distances. iSCSI provides shared storage among a number of client systems. Storage devices are attached to servers (targets). Client systems (initiators) access the remote storage devices […]
How to configure iSCSI Initiator (client) in CentOS / RHEL 7
Internet Small Computer System Interface (iSCSI) is an IP-based standard for connecting storage devices. iSCSI uses IP networks to encapsulate SCSI commands, allowing data to be transferred over long distances. iSCSI provides shared storage among a number of client systems. Storage devices are attached to servers (targets). Client systems (initiators) access the remote storage devices […]
How to configure iSCSI target using targetcli in CentOS / RHEL 7
Internet Small Computer System Interface (iSCSI) is an IP-based standard for connecting storage devices. iSCSI uses IP networks to encapsulate SCSI commands, allowing data to be transferred over long distances. iSCSI provides shared storage among a number of client systems. Storage devices are attached to servers (targets). Client systems (initiators) access the remote storage devices […]
How to configure iSCSI Initiator (client) in CentOS / RHEL 6
iSCSI is a protocol that allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. It is a popular Storage Area Network(SAN) protocol, allowing organizations to consolidate storage into data center storage arrays while providing hosts (such as database and web servers) with the illusion of locally-attached disks. […]
CentOS / RHEL 5 : How to Boot into Rescue Mode
It is possible to boot Linux in rescue mode using the installation media and bypassing the disk. During the rescue session, you can choose a network. Once the system is up, you will have access to the disk. Follow the below steps to boot in rescue mode: Note: In rescue mode, HDD/NIC will be recognized […]
How to backup Linux OS using “dd” Command
“dd” command can be really handy when it comes to taking an Operating System backup to clone the disk the OS is installed on. Here are few examples of using dd command for taking OS backup. NOTE: The target drive must be either of identical size to the drive being cloned or larger. The dd […]
How to clear the buffer/pagecache (disk cache) under Linux
Are you facing a performance issue and you suspect it might be related to cache usage? High cache usage should not normally cause performance issues, but it might be the root cause in some rare cases. What is Memory Cache In order to speed operations and reduce disk I/O, the kernel usually does as much […]
Understanding Special Permissions (setuid, setgid, sticky bit) in Solaris
In addition to the standard read, write, and execute permissions, Solaris and UNIX/LINUX in general has some special permissions that can be set to files and directories. These are the setuid bit, the setgid bit, and the sticky bit. Special Permissions on Files: SUID New Linux users often wonder why anyone would ever want to […]
Understanding How Umask Controls the Initial File / Directory Permissions in Linux
Controlling Initial File / Directory Permissions When new files and directories are created in Linux, default permissions are initially set. These permissions are calculated by taking the default permissions of the files/directories created and subtracting the umask value from it. The umask is a four-digit octal number that represents the value of permissions that will […]