How to mount both sc1 volume on Amazon EC2 instances - amazon-web-services

Question

My current 500GB Amazon EBS Cold HDD (sc1) volumes in /dev/sdf is full. Following the tutorial here (http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-expand-volume.html#migrate-data-larger-volume), I successfully got a 1.5 TB SC1, mounted in /dev/xvda and attached it to the instance. Please note that the 500 GB sc1 (/dev/sdf) is also attached to the instance.
Sadly, when I turned on the instance, I only see this new 1.5 TB SC1 in /dev/xvda, but not the old 500 GB SC1 in /dev/sdf and the corresponding data. When I do df -h:
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvdg1 1.5T 34G 1.5T 3% /
devtmpfs 7.9G 76K 7.9G 1% /dev
tmpfs 7.9G 0 7.9G 0% /dev/shm
If I turned off the instance, detached the 1.5 TB SC1 (/dev/xvda) from the instance, kept the attached 500 GB TB SC1 (/dev/sdf) to the instance, and finally restarted the instance, I will see the 500 GB TB SC1 (/dev/sdf) and its data in it again.
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sdf 500G 492G 8G 99% /
devtmpfs 7.9G 76K 7.9G 1% /dev
tmpfs 7.9G 0 7.9G 0% /dev/shm
Is there any way that we can mount both of these 2 volumes and see/transfer data between these 2 volumes in the same instance? Could any guru enlighten? Thanks.
#
Respond to the comment:
The following is the result of "lsblk" when both 500GB and 1.5GB SC1 are attached.
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part
xvdf 202:80 0 500G 0 disk
└─xvdf1 202:81 0 500G 0 part
xvdg 202:96 0 1.5T 0 disk
└─xvdg1 202:97 0 1.5T 0 part /
The following is the content in "/etc/fstab" when both 500GB and 1.5GB SC1 are attached.
LABEL=/ / ext4 defaults,noatime 1 1
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
extra comments:
UUID results
ls -l /dev/disk/by-uuid
total 0
lrwxrwxrwx 1 root root 11 Oct 19 08:54 43c07df6-e944-4b25-8fd1-5ff848b584b2 -> ../../xvdg1
#2016-10-21-update
After trying the following
uuidgen
tune2fs /dev/xvdf1 -U <the uuid generated before>
making sure both volumes are attached to the instance, restarting the instance, only the 500 GB volume show up.
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvdg1 493G 473G 20G 96% /
devtmpfs 7.9G 76K 7.9G 1% /dev
tmpfs 7.9G 0 7.9G 0% /dev/shm
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda 202:0 0 8G 0 disk
└─xvda1 202:1 0 8G 0 part
xvdf 202:80 0 500G 0 disk
└─xvdf1 202:81 0 500G 0 part /
xvdg 202:96 0 1.5T 0 disk
└─xvdg1 202:97 0 1.5T 0 part /
ls -l /dev/disk/by-uuid
total 0
lrwxrwxrwx 1 root root 11 Oct 20 20:48 43c07df6-e944-4b25-8fd1-5ff848b584b2 -> ../../xvdg1
lrwxrwxrwx 1 root root 11 Oct 20 20:48 a0161cdc-2c25-4d18-9f01-a75c6df54ccd -> ../../xvdf1
Also "sudo mount /dev/xvdg1" doesn't help as well. Could you enlighten? Thanks!

Answer 1

If the 2 disk are cloned and have the same UUID they cannot be mounted at the same time and system while booting will mount the first partition it finds.
Generate a new UUID for your disk
uuidgen
Running this will give you a new UUID - as the name implies it will be unique
Apply the new UUID on your disk
In your case xvdf is not mounted so you can change its UUID
tune2fs /dev/xvdf1 -U <the uuid generated before>
Change your mount point
Its getting better, however as they were clone both disk have the same mount point and that is not possible. you need to update your File System Table.
create a new folder which will be your mount point
mkdir /new_drive
mount the drive to your new mount point
sudo mount /dev/xvdg1 /new_drive
Update /etc/fstab so it will be mounted correctly on next reboot
Update the line about /dev/xvdg1 drive , you have something like
/dev/xvdg1 / ext4 ........
Change the 2nd column
/dev/xvdg1 /new_drive ext4 ........
All your data from the 1.5 TB are accessible in /new_drive. You can verify the file is correct by running mount -a
Please adapt this procedure if you want to change the folder name or if you want to keep the 1.5 TB as root mount point and change the 500 GB drive.