Monday, 16 January 2017

Re-scan the SCSI bus for new hard disks in CentOS 7

When adding additional disks (especially in virtualized environments) the Linux kernel will not always pickup the new disks straight away - so we have to manually re-scan the SCSI bus.

We should firstly identify which host controller the SCSI disks are attached to:

cat /sys/class/scsi_host/host?/proc_name

mptspi
ata_piix
ata_piix

* ata_piix and mptspi are the kernel modules for the controllers. See lsmod | grep ata_piix

We can see there are also two SATA controllers present - since we are after the SCSI one - we select

/sys/class/scsi_host/host0/proc_name

So lets invoke the re-scan manually - we do this with:

echo "- - -" > /sys/class/scsi_host/host0/scan

* The dash symbols represent a wildcard the channel number, SCSI target ID, and LUN values respectively.

Now check the kernel messages with dmesg:

dmesg | grep Attached


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