ext4

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How to enlarge root partition and filesystem size of cloud Linux VM at runtime without rebooting Linux

It is common that the root disk space is not enough when running a Virtual Machine in the cloud such as Amazon Web Service (AWS). The cloud storage usually provides tools or facilities to enlarge a virtual disk size. However, to make the Linux recognize and and use the enlarged disks without rebooting the OS,…

How to list start and end sectors of a partition by parted in Linux?

How to list start and end of a partition by the sectors in parted on Linux? The default behavior seems be listing the start and end by bytes in parted. # parted /dev/sdc print Model: Innostor IS888 ext. HDD (scsi) Disk /dev/sdc: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End…

What is the difference between work conserving I/O scheduler and non-work conserving I/O scheduler?

What is the difference between work conserving I/O scheduler and non-work conserving I/O scheduler? In a work-conserving mode, the scheduler must choose one of the pending requests, if any, to dispatch, even if the pending requests are far away from the current disk head position. The rationale for non-work-conserving schedulers, such as the anticipatory scheduler…

mkfs refuses to make filesystem with message “is apparently in use by the system; will not make a filesystem here!”

I have a disk from another server installed on a new server. However, when I try to make a filesystem on it, mkfs reports # mkfs -t ext4 /dev/sdd1 mke2fs 1.42.8 (20-Jun-2013) /dev/sdd1 is apparently in use by the system; will not make a filesystem here! This is a new disk to the new server….

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Controlling Filesystem Mounting on Linux using /etc/fstab

Controlling the mounting of filesystems is a useful technique for managing Linux systems. The mounting configurations are mostly in the /etc/fstab file. In this post, we will discuss 2 common and useful techniques for controlling the filesystem mounting by playing with the /etc/fstab file: allowing non-root users to mount/unmount filesystems and avoiding mounting failures blocking…

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Making GPT Partition Table and Creating Partitions Using parted in Linux

My best favorite disk partition table manipulation tools are cfdisk/fdisk on Linux. However, for large disks, cfdisk/fdisk (of the versions by this post is written) will just give up with a message suggesting GPT partition table format and using GNU parted like WARNING: The size of this disk is 6.0 TB (6001042391040 bytes). DOS partition…

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Setting Up Xen Dom0 on Fedora : Xen 3.4.1 with Linux Kernel 2.6.29 on Fedora 12

Please refer to for the latest stable Xen Dom0 solution. In this post, the detailed tutorial for setting up Xen 3.4.1 dom0 on top of Fedora 12 with kernel 2.6.29 will be introduced. Hardware: Dom0 hardware platform: Motherboard: INTEL S5500BC S5500 Quad Core Xeon Server Board CPU: 2 x Intel Quad Core Xeon E5520 2.26G…

An I/O Performance Comparison Between loopback Backed and blktap Backed Xen File-backed VBD

I have done some I/O performance benchmark test of Xen DomU. For easier management, some of our DomU VMs are using file-backed VBDs. Previously, our VMs are using Loopback-mounted file-backed VBDs. But blktap-based support are recommended by Xen community. Before considering changing from loopback based VBD to blktap based VBD, I have done this performance…