Rescan a SCSI bus without rebooting
After adding a hotplug-capable HDD to Linux, whether on a VM or physical machine, # fdisk -l may not show it until reboot. Rescanning SCSI can detect it without rebooting.
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Storage & filesystems.
25 articles on this topic
How to get UUID of the hard disk in Linux syetem
Newer Linux versions use UUIDs to identify hard disks instead of device names. This prevents the system from using the wrong disk when there is more than one and a disk fails or is removed…
How to create a partition size larger than 2 TB on linux
Disks larger than 2 TB require a GPT-capable partitioning tool. gdisk works much like fdisk and supports large disks and up to 128 partitions.
How to calculate storage size for Zimbra mail server
Planning storage capacity is important: without estimating the total space required, the system may run out of storage. This article shows how to calculate the requirement.
Fix a prefix of it is already part of a volume on GlusterFS
When reusing a removed GlusterFS brick, adding it may fail with /path/app or a prefix of it is already part of a volume. Here is how to resolve it.
Format NTFS partition on external hard drive from CentOS / RHEL linux
After writing about mounting NTFS on CentOS / RHEL, I wanted to share how Linux can format a hard disk with an NTFS filesystem without using Windows.
How to mount NTFS filesystem with read/write support on CentOS / RHEL linux
NTFS is a Windows filesystem. ntfs-3g, led by Szabolcs Szakacsits, provides read/write support without recompiling, including a free community edition.
Change I/O Disk Scheduler without Reboot
There are four I/O schedulers for hard disks and block devices: anticipatory, noop, deadline, and CFQ. CFQ is usually the default. To change the I/O scheduler…
How to Set up GRUB to boot from both disks of mirrored RAID
On Linux software RAID 1, GRUB normally boots from the primary disk. Configure it on the secondary disk too so the system can boot if the primary fails.
What is smartd and how to use it
smartd monitors hard disks using SMART, or Self-Monitoring, Analysis, and Reporting Technology, to analyze, check, report status, and predict whether a hard disk…
Rescan SCSI to add, remove SCSI device without rebooting
To rescan an entire SCSI bus and re-register all devices found: rescan SCSI so the system sees a new device. On some Linux systems, this also adds or removes devices.
How to read hard drive device files name
Linux stores device files in /dev/, with names depending on device type. This article explains how to identify hard drive names and their prefixes.
How to add a new hard disk to linux system.
Adding a hard disk to Linux is simpler than some people think, though slightly harder than in Microsoft Windows. You need to understand partitioning, filesystems, and mounting.
Export a directory with NFS v4
A major difference between NFS v4 and earlier versions is the ability to export a single directory in a way similar to an FTP or web server, such as exporting /shared.
Fix the following error; LVM error VG meta data inconsistent
Resolve LVM error VG meta data inconsistent by booting into rescue mode, restoring VG metadata, rescanning devices and groups, and activating the volume group.
Suggested I/O scheduler for a Video on Demand (VOD) server using Red Hat Enterprise Linux
On a VOD server, using the cfg scheduler can increase disk I/O latency when many connections arrive, leading to uneven video playback.
Decrease the time for rebuilding the RAID 1 array
To reduce RAID 1 rebuild time, use: # mdadm -C /dev/md0 -l1 -n2 /dev/sda1 /dev/sda2 --bitmap=internal. --bitmap (Write-intent bitmap) reduces synchronization time…
Re-shape or Grow a Raid 5 array.
Growing Linux software RAID is straightforward. This example adds /dev/sdd1 to a three-disk RAID 5 array at /dev/md0, then grows the array and filesystem.
Reduce a non-root LVM.
This example reduces a 10 GB LVM volume to 8 GB, assuming it is mounted at /data, by shrinking the filesystem before reducing the logical volume.
Access a USB flash drive in Linux.
Linux normally mounts USB flash drives or thumb drives automatically when you plug them in. Sometimes it does not, which can frustrate new users…
Create filesystems greater than 2 Terabytes
CentOS/RHEL 5 supports filesystems up to 8 TB, with 16 TB planned for the future. In practice, filesystem creation may stop at 2 TB; this article gives a workaround.
Force fsck on the next boot sequence
To have Linux check every partition's file system after a reboot, use these commands as root. Create /forcefsck in the root directory to force a check on the next boot…
How to rescan the SCSI bus to add or remove a SCSI device without reboot
Linux supports online SCSI rescans, allowing drives to be rescanned without restarting the system.
Install Device Mapper Multipathing on SAN/NAS
This is an older article brought up to date because some readers may not know what device-mapper multipathing is for. It provides multipathing for storage devices such as SAN or NAS…
How to add a swap partition to my system
To add a new SWAP partition, you need an unused partition with its type set to Linux-SWAP. For example, suppose /dev/hdb3 is unused. Steps to create SWAP…