Linux – Add a SCSI disk on Linux without rebooting

linuxsatascsi

I added new disk to my running Linux virtual machine.

Is it possible to add a SCSI/SATA device explicitly, or to re-scan an entire SCSI/SATA host bus without rebooting a running Linux?

Best Answer

Yes, it is possible. There are some methods to do it:

Add a single device

 echo "scsi add-single-device <Host> <Bus> <Target> <Lun>" > /proc/scsi/scsi

In my case, I added the only SCSI/SATA disk on Host=8, so the command is

echo "scsi add-single-device 8 0 0 0" > /proc/scsi/scsi

Rescan SCSI/SATA Host Bus

If there were more than one disks added to your system, you can scan all devices on explicit SCSI/SATA Host

echo "- - -" > /sys/class/scsi_host/hostHOSTNUM/scan

I.e. if the disk was added to Host=8, the command is

echo "- - -" > /sys/class/scsi_host/host8/scan

Rescan all SCSI/SATA Hosts

Generally, if you don't know a host number of added disk, you can scan the whole SCSI hosts on your machine.

Get a list of SCSI/SATA hosts:

  1. Use lsscsi to get a list of hosts: lsscsi -H

  2. Use sysfs to get a list of hosts: ls -d /sys/class/scsi_host/host*.

Rescan given host: echo "- - -" > /sys/class/scsi_host/hostX/scan

Simple full scan automation script

#/bin/bash
# ReScan all SCSI/SATA Hosts
for SHOST in /sys/class/scsi_host/host*; do
    echo -n "Scanning ${SHOST##*/}..."
    echo "- - -" > ${SHOST}/scan
    echo Done
done

Sources were used in this answer:

EVAN HOFFMAN'S BLOG

nixCraft

RedHat Customer Portal

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