- An instance running on Amazon EC2
- It is an m1.large EC2 instance
- The instance is running Ubuntu Server 12.04 LTS
Here's What Happens...
I wanted to measure disk IOPS on my system, and it looked like
iostat was the right tool for the job. Please find below sample output from
iostat on my system:
user@host:~$ iostat Linux 3.2.0-61-virtual (host) 05/06/2014 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 7.26 0.00 1.84 0.23 0.08 90.60 Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn xvdap1 6.55 54.12 77.60 618193 886348 xvdb 0.03 0.13 0.00 1477 4
The above seems to give me the information I'm looking for, except it lists a block device that doesn't exist on my system.
If we examine
lsblk, we do not find a device named
user@host:~$ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT xvda1 202:1 0 10G 0 disk / xvdb 202:16 0 420G 0 disk /mnt
xvdap1 cannot be found in
user@host:~$ ls /dev/xvd* /dev/xvda1 /dev/xvdb
I'm inclined to believe that
xvdap1 is the same as
/dev/xvda1, but why on earth would they have two different names? The two names differ by a single letter p, what does the p mean?