Wednesday, February 19, 2014

Detect a New Disk and Grow a Filesystem in Linux without Rebooting

If you have ever wanted to add a new hard disk to a Linux VMware guest without rebooting here is the solution. After running this command you should be able to use the new disk as you please. This is really useful for growing an LVM filesystem on the fly.
Run this command after adding the new disk to you VMware configuration. This will allow your Linux guest to detect the new disk and assign it as a device.
ls /sys/class/scsi_host/ | while read host ; do echo "- - -" > /sys/class/scsi_host/$host/scan ; done
Once you have ran this command you can grow the LVM filesystem as usual. (Where X is the new device added.)
# Create a new partition on the new disk. Assign it the type of Linux LVM, 8e.
fdisk /dev/sdX

# Create the new physical volume.
pvcreate /dev/sdX1

# Extend the volume group of your choice.
vgextend /dev/VolumeGroupName /dev/sdX1

# Confirm the new physical extents are available and take note of the number.

# Extend a logical volume where 1234 is the number of PEs you would like to add.
lvextend -l +1234 /dev/VolumeGroupName/LogVolName

# Resize the EXT filesystem.
resize2fs /dev/VolumeGroupName/LogVolName

# Confirm the new space is available.
df -h
Once complete you should have extra space on your Linux guest.

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