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I was running a small instance on Amazon EC2. I'm trying to migrate it to a micro as it requires very minimal processing power. One thing I just learned though, is that micro instances do not come with ephemeral storage like the other instance sizes.

Here is the fstab file from the small instance. I just added the nobootwait for the /dev/sda3 line.

/dev/sda1  /         ext3    defaults                0 0
/dev/sdb   /mnt      ext3    defaults                0 0
/dev/sda3  swap      swap    defaults,nobootwait     0 0
none       /dev/pts  devpts  gid=5,mode=620          0 0
none       /dev/shm  tmpfs   defaults                0 0
none       /proc     proc    defaults                0 0
none       /sys      sysfs   defaults                0 0
/dev/sdf   /apps/    ext3    defaults,acl            1 1
/dev/sdg   /data/    ext3    defaults                1 1

Now when I launch this instance as a micro I get a warning:

Mounting local filesystems:  mount: special device /dev/sdb does not exist [FAILED]

It still boots up fine and things seem to be working great, but is there anything I'm missing that I would need the ephemeral storage for that I'm not seeing or thinking about?

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From the Amazon EC2 docs, it sounds like the instance storage drive mounted on /mnt is just some local scratch space that is not backed up or shared. You should be considering your own usage and asking yourself the question of whether you need it or not. – jw013 Aug 3 '12 at 15:36
I suppose what I meant is do any system components need it. The filesystem type is swap. At least on windows it's a very bad idea not to have a swap file. Thank goodness this isn't windows. – cwd Aug 3 '12 at 15:50
up vote 1 down vote accepted

The AMI will work fine, as-is. The only reason you would need it is if your workflow/application needs it.

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