NFS

Linux & Systems Administration

Configuring Xen HVM DomU Systems
ByQ A Mar 24, 2018Apr 13, 2026

Xen HVM (Hardware Virtual Machine) guests require a configuration file that defines virtual hardware, networking, and boot parameters. Here are practical examples for common scenarios. Installation Configuration Use this configuration when installing a guest OS from an ISO: name=”10.0.1.235″ vcpus=2 memory=2048 shadow_memory=8 disk=[‘file:/lhome/xen/vm-10.0.1.235/vmdisk0,xvda,w’, ‘file:/lhome/Linux-x86_64-DVD.iso,xvdc:cdrom,r’] vif=[‘bridge=xenbr0′] kernel=’/usr/lib/xen/boot/hvmloader’ builder=’hvm’ device_model=’/usr/lib64/xen/bin/qemu-dm’ vnc=1 vnclisten=”0.0.0.0″ vncpasswd=’your-secure-password’ on_reboot=’restart’ on_crash=’restart’ Key points…

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Testing & DevOps

Efficiently Copy Large Sparse Files with SEEK_HOLE and SEEK_DATA
ByEric Ma Mar 24, 2018Apr 12, 2026

Archiving or copying a 1TB sparse file containing only 32MB of actual data is impractical with naive approaches—you’ll waste time and I/O bandwidth copying zeros. The solution is using SEEK_HOLE and SEEK_DATA flags with lseek(), which allow tools to skip over hole regions entirely. How SEEK_HOLE and SEEK_DATA work The Linux kernel provides two additional…

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Development Best Practices

Exporting NFSv4 Shares to External Networks
ByEric Ma Dec 16, 2017Apr 12, 2026

NFSv4 significantly simplifies network exposure compared to NFSv3. Where NFSv3 requires managing multiple dynamic ports (mountd, statd, lockd), NFSv4 uses only port 111 (rpcbind) and port 2049 (NFS). This makes firewall configuration and port forwarding straightforward. For production environments, consider implementing Kerberos authentication (krb5, krb5i, or krb5p) instead of relying solely on network-based access control….

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Linux & Systems Administration

How to Unmount a Busy Filesystem in Linux
ByEric Ma May 21, 2016Apr 12, 2026

When you try to unmount a filesystem with umount, Linux may report “device is busy.” This is a safety mechanism — the kernel blocks unmounting when processes or kernel threads are actively accessing the partition or holding open files on it. Forcing an unmount without understanding what’s using the filesystem risks data corruption and data…

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Linux & Systems Administration

Configuring /etc/fstab: Mount Options and Boot Behavior
ByEric Ma Mar 25, 2015Apr 12, 2026

The /etc/fstab file defines how Linux mounts filesystems at boot and controls mounting behavior for both the system and individual users. Understanding its format and options is essential for reliable storage management. File Format and Fields Each line in /etc/fstab represents one filesystem. Fields are separated by whitespace (tabs or spaces), and lines beginning with…

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Linux & Systems Administration

Configuring Static Ports for NFSv3 RPC Services
ByEric Ma Oct 25, 2013Apr 12, 2026

NFSv3 uses multiple RPC services, each requiring its own port assignment. Without explicit configuration, rpcbind assigns random high ports to four critical services, making firewall rules unmaintainable. Modern deployments should prioritize NFSv4 with Kerberos, but legacy NFSv3 environments remain common enough to warrant proper port management. The NFS service stack includes seven RPC programs: Service…

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Linux & Systems Administration

OpenLDAP and NFS for Centralized User Authentication
ByEric Ma Sep 25, 2013Apr 12, 2026

This guide sets up OpenLDAP for centralized authentication and NFS with automount to provide unified home directories across a cluster. The setup uses modern OpenLDAP backends and current NFS4 best practices. System Environment Server: LDAP and NFS: 10.0.0.2, Fedora 41 x86_64 Base DN: dc=lgcpu1 Clients: Range: 10.0.0.1/24, Fedora 41 x86_64 LDAP Server Setup Package Installation…

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Linux & Systems Administration

Recovering from fstab Boot Failures: A Practical Guide
ByEric Ma Aug 25, 2013Apr 12, 2026

When /etc/fstab contains errors or your hardware configuration changes, the system may fail to boot or hang during the mount phase. You can recover by modifying kernel parameters at boot time to bypass automatic mounting, then repair the configuration. Method 1: Boot to Single-User Mode Single-user mode skips mounting filesystems listed in fstab, letting you…

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Linux & Systems Administration

Setting Up NFS Server and Client Configuration
ByEric Ma Jul 13, 2013Apr 12, 2026

Package Installation Install the required packages: dnf install nfs-utils nfs-utils includes both server and client tools. The separate rpcbind package is no longer needed on modern systems — it’s handled as a dependency and runs as part of the NFS service. Configure /etc/exports Edit /etc/exports to define which directories clients can mount and with what…

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Linux & Systems Administration

Building Distributed Systems on Linux
ByEric Ma Jul 13, 2013Apr 12, 2026

Building and maintaining Linux clusters requires coordinated management of user accounts, storage, networking, and services across multiple machines. This guide covers practical approaches to common clustering challenges, from unified authentication to network isolation. Account and Storage Management Unified Authentication and Home Directories Centralizing user management across cluster nodes eliminates the overhead of maintaining individual user…

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Linux & Systems Administration

NFS Server on tmpfs: Setup and Caveats
ByEric Ma Jul 13, 2013Apr 12, 2026

tmpfs delivers exceptional I/O performance since it lives entirely in RAM. Exporting it via NFS can be useful for temporary caches, build artifacts, or high-speed data sharing between systems on a trusted network. The catch: NFS needs additional configuration to export pseudo-filesystems like /dev/shm. Without the right settings, you’ll hit access denied errors or fsid…

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Linux & Systems Administration

Mounting Remote Folders via SSH with SSHFS
ByEric Ma Jul 13, 2013Apr 13, 2026

sshfs is the standard tool for mounting remote filesystems over SSH. It’s available in most distribution repositories. Debian/Ubuntu: sudo apt install sshfs RHEL/CentOS/Fedora: sudo dnf install sshfs Alpine: apk add sshfs On some systems you may need to ensure the fuse kernel module is loaded: sudo modprobe fuse Basic Mount Mount a remote directory to…

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