Yes. You can. Check this:
Before attaching a new volume:
root@ip-10-254-158-102:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda1 202:1 0 20G 0 disk /
root@ip-10-254-158-102:~# date
Fri Mar 7 06:40:21 UTC 2014
After Adding a new volume of 100GB:
root@ip-10-254-158-102:~# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
xvda1 202:1 0 20G 0 disk /
xvdg1 202:97 0 100G 0 disk
root@ip-10-254-158-102:~# date
Fri Mar 7 06:40:55 UTC 2014
I put the date
output just to show that the volume was attached within 34 seconds, the time I took to attach the volume from AWS Console. (meaning, without rebooting the instance because the instance reboot will definitely take more than 34 seconds :-) ).
Also, I could finds this new volume detected in fdisk
# fdisk -l
Disk /dev/xvda1: 21.5 GB, 21474836480 bytes
......
Disk /dev/xvda1 doesn't contain a valid partition table
Disk /dev/xvdg1: 107.4 GB, 107374182400 bytes <<< This is the one.
......
Disk /dev/xvdg1 doesn't contain a valid partition table
However, I could not find anything being logged to dmesg
. But the volume was attached and later I could mount it as well.
BTW, this is was tested on an Ubuntu 12.04 AMI.