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Attaching a Volume

  • Create a volume from the AWS panel
  • SSH into your instance
  • Run lsblk "to view your available disk devices and their mount points"
  • You will likely need to create a file system on a new drive. Run sudo file -s /dev/xvdXXX to list system type.
  • If the file type is "sticky data" and you know the drive is empty, run sudo mkfs -t ext4 /devx/xvdXXX to build a Linux filesystem on the drive.
  • Use $ sudo mkdir to create a mount point. It is in good form to mount under /mnt
  • Mount by running sudo mount /dev/DEVICE_NAME /mnt/MOUNT_POINT
  • $ df -h to see if everything mounted correctly
  • Optionally, make symbolic links from the mount point into your home directory, or wherever else.
  • Think about group ownership and permissions to the mount point. Use $ chgrp, $ chmod to fix this, depending on your setup.

Automate attachment on server reboot

  • Don't touch anything until you take the filesystem tour.
  • Make a copy of your fstab by running $ sudo cp /etc/fstab /etc/fstab.orig
  • Tread carefully here, if you brick fstab your server will hang on boot--if that happens, detach root volume from your instance, attach to a new instance as a secondary volume, restore fstab and reattach to the original instance
  • $ man fstab before touching anything
  • Edit fstab. It should look something like this:
# <source>      <mount point>           <type>          <options>                     <dump> <pass>
/dev/xvda1      /                       ext4            defaults,barrier=0            1       1
/dev/xvdb       /mnt/osp-archive-mount  ext4            nofail,defaults               1       2

xvda1 in this case is my root (setup automatically), and xvdb is the one I added. The nofail option is quite important--it will ignore the drive if the system is not able to mount it on boot

  • $ sudo umount /dev/xvdb to unmount the disk
  • $ sudo sudo mount -a to try mounting using your new fstab options
  • Say a little prayer and stop + restart your instance through the AWS console. If all goes well you will be able to login after restart and your drive will be mounted. (Don't forget to re-associate your elastic IP).

Nightly Backup to Glacier

We now want to automate backups to Amazon's cheap Glacier storage. We are going to be using the AWS Snapshot Tool by evannuil.

  • Begin by installing python package manager pip. It will look something like: sudo aptitude install python-pip
  • Install Boto, the Python interface to Amazon Web Services. It will probably look something like this: sudo pip install boto
  • Create the boto.cfg file which will hold your credentials. `sudo vim /etc/boto.cfg' Follow the instructions here. In my case it looks something like this:
[Credentials]
aws_access_key_id = <your_access_key_here>
aws_secret_access_key = <your_secret_key_here>
  • Change permissions to boto.cfg to read / write access by sudo only. sudo chmod 600 boto.cfg
  • Setup IAM through AWS console.
"Action": [
        "ec2:CreateSnapshot",
        "ec2:CreateTags",
        "ec2:DeleteSnapshot",
        "ec2:DescribeAvailabilityZones",
        "ec2:DescribeSnapshots",
        "ec2:DescribeTags",
        "ec2:DescribeVolumeAttribute",
        "ec2:DescribeVolumeStatus",
        "ec2:DescribeVolumes"
      ],
  • Setup messaging.
  • Install AWS Snapshot Tool.
  • Configure AWS Snapshot Tool:
config = {
    'ec2_region_name': 'us-east-1',
    'ec2_region_endpoint': 'ec2.us-east-1.amazonaws.com',
    'tag_name': 'tag:MakeSnapshot',
    'tag_value':    'True',
    'keep_day': 5,
    'keep_week': 5,
    'keep_month': 11,
    'log_file': '/tmp/makesnapshots.log',
}
  • Tag volumes
  • Crontab:
$ crontab -l

# mon-fri 30 3 * * 1-5 /home/zope/aws-snapshot-tool/makesnapshots.py day

# every sat 30 3 * * 6 /home/zope/aws-snapshot-tool/makesnapshots.py week

# first sun 30 3 1-7 * 0 /home/zope/aws-snapshot-tool/makesnapshots.py month

Growing Volumes

  • Stop instance (through the AWS panel)
  • Detach volume (in AWS panel)
  • Make a snapshot of the old volume (in AWS panel)
  • Create a new, larger volume form the snapshot. Make sure it is in the same zone.
  • Attach new volume.
  • Log into the server. Run $ e2fsck -f /dev/sdx2 to check the file system on the new block.
  • Run $ resize2fs -p /dev/sdx2 to resize.
  • Run $ e2fsck -f /dev/sdx2 and $ tune2fs -l /dev/sdx2 for diagnostics. e2fsck might be in /sbin.
  • Mount the volume by running $ mount /dev/sdx2 /mnt/ebs2
  • $ df -h to see disk space usage

Sources + Useful Links