File System Extension on Live Linux VMware Guest using vmdisk size extended

By Parthiban Ponnusamy



Many thanks to RAM for this Article.

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This article explains, Filesystem extension on live Linux VMware Linux Guest where vmdisk size is extended and by not new disk added.

We had a scenario as follows:

1.       File system extension requirement on a live mounted file system without reboot.
2.       It’s a Linux guest on VMware required a FS extension from 600 GB to 900 GB. The FS was a single 600 GB disk  /dev/sdb
3.       While assigning storage, the team did increase the underlying disk to 900 GB than adding a new disk.
4.       Even after extension,  /dev/sdb was not picking up the additional 300 GB space. [ rescan or partprobe did not help here ]

Note: The case also applies for situations where you have the underlying partition has been changed ( using fdisk ).

Following are the steps taken to make the kernel recognize the new partition structure and to extend the filesystem

First we verified the disk sizes and allocations

# pvs
# vgs
# lvdisplay -m /dev/vg_name/lv_name  [ to get the underlying block devices ]
 
Now we had the partition table re-read for the underlying block device.

blockdev --rereadpt /dev/sdb
OR# sfdisk –R /dev/sdb

Do note that if you are doing this on a physical machine where we have multipath involved, we would need to re-read the partition tables for all the underlying disks involved.

Now that we have the partition table re-read, we would need to make PV resized to the new disk. Else it would still show the old size.

pvresize /dev/sdb

Check pvs / vgs output to see whether the new size is detected:

# pvs
# vgs

Once you have the new size detected, you can use the standard procedure to extend the filesystems

# lvextend -L +300G /dev/vg/lv
# resize2fs /dev/vg/lv

Check whether the new file systems are showing the correct sizes:

# df -h


Following are the screenshots of the entire activity which I performed in a test VM. A test VG and LV were created for this activity.

Verify current disk size of the mounted volume :



Check and verify on the available disk space on the underlying disk(s)



Increased the size of the vmware disk than adding a new disk in the virtual machine settings in vCenter.


Now,

Make the new sizes/partition visible on the system without reboot or taking the volume offline:



Extend the LV:



Resize FS: