Rescan SCSI or FC devices
When you are playing with SCSI devices (like Fibre Channel, SAS, ..) you sometimes need to rescan the SCSI bus to add devices or to tell the kernel a device is gone. Well, this is the way to do it in CentOS with versions that have a 2.6 kernel. This means CentOS 5 and CentOS 4 (starting from update 3).
Find what's the host number for the HBA:
(You'll have something like host1 or host2, I'll refer to them as host$NUMBER from now on)
Ask the HBA to issue a LIP signal to rescan the FC bus:
echo 1 >/sys/class/fc_host/host$NUMBER/issue_lip
Wait around 15 seconds for the LIP command to have effect
Ask Linux to rescan the SCSI devices on that HBA:
echo - - - >/sys/class/scsi_host/host$NUMBER/scan
The wildcards "- - -" mean to look at every channel, every target, every lun.
Rescan for after disk was extended
echo "1" > /sys/block/sda/device/rescan
How to use a new partition in RHEL6 without reboot?
partx -a /dev/sd
existing disk extending on RH6
echo 1 > /sys/block/sda/device/rescan fdisk -l fdisk /dev/sda partx /dev/sda partx -a /dev/sda pvcreate /dev/sda4 vgextend VG01 /dev/sda4 lvextend -L +14G /dev/VG01/logs lvextend -L +14G /dev/VG01/var resize2fs /dev/VG01/logs resize2fs /dev/VG01/var df -h