To follow-up and provide a conclusion to my issue, in case anyone else
runs into a similar situation.
TLDR - go to bottom and read item #7.
To recap the issue:
I have a Dell PowerEdge server with a CentOS KVM host (Earth) with
one CentOS guest (Sequoia) that I am trying to expand the partition and
filesystem on. I have LVM logical volumes on the host system (Earth),
which are used as devices/partitions on the guest system (Sequoia). In
this particular situation I have successfully extended the logical
volume (lv_SeqEco) on Earth from 500GB to 700GB.
1. Checking the disk information (lsblk) on Earth shows that the
logical volume (lv_SeqEco) is now listed as 700GB.
2. Checking disk information (lsblk) on Sequoia shows that the disk
/dev/vde is still listed as 500GB, and partition /dev/vde1 where the
mount point /ecosystem is located is also listed as 500GB.
3. I had tried using the resize2fs command to expand the filesystem on
/dev/vde1, but it returned with the result that there was nothing to
do. Which makes sense now after I checked the disk information, since
/dev/vde on Sequoia has not increased from 500GB to 700GB.
4. On previous occasions when I have done this task, I would just start
GParted on Sequoia and use the GUI to expand the partition and
filesystem. I am unable to do this now, as the VGA adapter on my server
has died and I have no graphical output to the attached monitor.
5. My goal was to not have to not have to reboot the system. Especially
since it is a 10-year old server and there is no longer VGA output to
view the boot process.
What I tried, and what worked to solve my issue:
1. First, I tried rescannning the device on the guest:
echo 1 >
/sys/devices/pci0000:00/0000:00:01.1/host1/target1:0:0/1:0:0:0/rescan
This resulted in no output, and checking lsblk on the guest (Sequoia)
showed no change:
vde 500GB disk
vde1 500GB part /ecosystem
2. Second, I tried using "virsh blockresize" from the host (Earth) system.
Get the block size information
earth# virsh domblkinfo SequoiaVM vde
output: vde capacity 751619276800
Resize the block (express the size in Bytes)
earth# virsh blockresize SequioaVM vde 751619276800B
output: Block device vde is resized.
Check the block device on the guest to confirm.
sequoia# lsblk
vde 700GB disk
vde1 500GB part /ecosystem
Therefore, virsh blockresize was successful.
3. I now have the larger disk recognized on the guest system, but still
need to expand the partition and the filesystem. Tried the following
options.
resize2fs -p /dev/vde1
output: filesystem is already xx blocks long, nothing to do.
growpart /dev/vde 1
output: This showed output indicating the partition had changed
changed: partition=1 start=63
old: size=1048575937
end=1048576000
new: size=1468003572
end=1468003635
However, checking lsblk on the guest still showed the same result
vde 700GB disk
vde1 500GB part /ecosystem
On the off chance that growpart was successful, I ran resize2fs again
and it produced the same result as above.
partprobe
output: failed to re-read the partition table on all attached
devices (including /dev/vde1); device or resource busy.
Tried using "parted" and its resize command. First, using the print
command to get the parameters of /dev/vde (output: end=751617861119B,
size=751617828864B). Then changing parted to select (use) /dev/vde1 and
used print command to view parameters of /dev/vde1 (output:
end=536870879743B, size=536870879744B).
(parted)# resize 1 0 751617861119
output: The location 751617861119 is outside of the device /dev/vde1
Looked at using fdisk; however, the documentation stated that the only
way to change the partition size using fdisk is by deleting it and
recreating it. I didn't want to do this.
I finally decided that everything indicated that I would not be able to
complete this while the system was online and/or mounted, despite all my
research information showing that.
4. Unmounted the filesystem of the guest and run partprobe.
sequoia# service smb stop
sequoia# umount /ecosystem
sequoia# partprobe
output: This produced the same warnings as before (failed to
re-read the partition, device busy) for all partitions that were still
mounted, but did not produce the warning for partition /dev/vde1 that
had been unmounted.
sequoia# lsblk
vde 700GB disk
vde1 700GB part /ecosystem
Success. The new partition is now recognized in the kernel, and I
should now be able to resize the filesystem.
5. Run resize2fs
sequoia# resize2fs -p /dev/vde1
output: please run e2fsck -f /dev/vde1 first
sequoia# e2fsck -f -C 0 /dev/vde1 (-C 0 will display the progress)
output: system passed all checks.
sequoia# resize2fs -p /dev/vde1
output: resizing the filesystem on /dev/vde1 to 183500446 (4k)
blocks, begin Pass 1, extending inode table, filesystem is now 183500446
blocks long.
6. Remount the filesystem and check the filesystem size.
sequoia# mount /dev/vde1 /ecosystem
sequoia# service smb start
sequoia# df -h
filesystem=/dev/vde1
size=689G
used=459G
available=196G
used%=71%
mount=/ecosystem
7. So in conclusion I needed to do the following steps to resize and
expand my disk without a reboot. There may still be other ways that
this can be accomplished, but this worked for my CentOS 6 system (both
host and guest).
a. On the host system, lvextend to expand the logical volume used by
the guest as it's disk.
b. On the host system, virsh blockresize to get the guest system to
recognize the expanded disk space.
c. On the guest system, growpart to grow the partition to the
expanded space.
d. On the guest system, unmount the filesystem (stop services as
required).
e. On the guest system, partprobe to get the kernel to recognize the
expanded partition.
f. On the guest system, resize2fs (run filesystem check if required)
to expand the filesystem.
Thanks to all that provided suggestions and insight, it was very helpful
in my research and methodical stepping through this process.
Jeff
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