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This may be a silly question, excuse my ignorance.

I have an instance running like this: AWs Console

Does Root Device : EBS mean my entire system is on EBS?

I've configured apache and a perl app here, all my config and files will not go away right?

How do I know what is running on ephemeral storage and what is running on EBS? If I click the instance in the management console and look at the details in the bottom it says : EBS Optimized: false What exactly does this mean?

Here is what my storage looks like :

[ec2-user@<MY_IP> ~]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/xvda1            7.9G  1.7G  6.2G  22% /
tmpfs                 298M     0  298M   0% /dev/shm

[ec2-user@<MY_IP> ~]$ mount
/dev/xvda1 on / type ext4 (rw,noatime)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
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t1.micro instance don't have any ephemeral storage, only m1.small or above has. –  number5 Jan 21 '13 at 10:35
Ah nice. Didn't know that. No wonder I don't see any options. –  gideon Jan 21 '13 at 11:26

2 Answers 2

up vote 1 down vote accepted

Root device is your '/'. In this case it's /dev/xvda1 and it's EBS drive.

Ephemeral devices are (as I know):

  • sdb(xvdb)
  • sdc(xvdc)
  • sdd(xvdd)
  • sde(xvde)

You can always check which devices are EBS drives, using AWS UI: EC2 -> Instances -> [choose yours] -> Block Devices

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Awesome. Thanks :) Whats all the sysfs1, devpt and what not. –  gideon Jan 20 '13 at 10:37
tmpfs is similar to ramfs and allow to keep files in fast RAM. devpts and sysfs are "virtual" linux filesystems, that provide access to some kernel data. You can check more on google - there are plenty of articles about them. –  Tomasz Olszewski Jan 20 '13 at 10:41
I see. Thanks :) –  gideon Jan 20 '13 at 10:44
xvda1 Xvdd xvdc xvdb These are EBS volumes. How can you say these are ephemeral? –  Panna Jun 12 at 10:33

sudo lsblk should give you some hints. I.E.

[ec2-user@ec2-host ~]$ sudo lsblk
xvda    202:0    0   8G  0 disk 
└─xvda1 202:1    0   8G  0 part /
xvdb    202:16   0   4G  0 disk /media/ephemeral0
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