EBS:
(Elastic Block Storage) (Disk in a Cloud)
Provides block-level
storage volumes: -
Amazon EBS allows you to create storage volumes and attach them to
Amazon EC2 instances. Once attached, you can create a file system on top of
these volumes, run a database, or use them in any other way you would use a
block devices. Supports up to 16 TB.
Cost is calculated from
GB/month of total allocated size
·
Even if nothing is stored on it.
Ability to store
information off an EC2 instance.
·
Volumes can be attached and detached to EC2
instances
·
Volumes persist after terminating an instance.
Amazon EBS volumes are
placed in a specific Availability Zone
Can only be attached to
instances within the same zone
·
Can only be attached to one instance at a time
·
Many volumes can be attached to a single
instance
Volumes are automatically
replicated across AWS servers within the zone
·
To improve reliability, availability, and
durability
·
Prevents data loss due to single hardware
failure
o
Not designed for durability or considered highly
durable
o
Designed to be better than storing data on a
single hard drive
·
Snapshots can be used to provide highly durable
backups
EBS
Volumes Types
·
General
Purpose SSD (GP2)
o
Designed for 99.999% availability
o
Ratio of 3 IOPS per GB with up to 10000 IOPS and
the ability to burst up to 3000 IOPS for short periods for volumes under 1 Gib.
·
Provisioned
IOPS SSD (I01) (Input output Per Second)
o
Designed for I/O intensive applications such as
large relational or NoSQL databases. Use if you need more than 10,000 IOPS
·
Magnetic
(Standard)
o
Lowest cost per gigabyte to all EBS volumes
types. Magnetic volumes are ideal for workloads where data is accessed
infrequently, and applications where the lowest storage cost is important.
Creating EBS Volume
Attaching an EBS Volume
Mounting an EBS Volume
·
Once attached, a volume must be mounted in the
actual instance
o
Depends on OS
·
Volume must also be formatted before use
o
New volume appear as zeroed-out raw block-level
storage
o
Can format as any file system desired
§ Depends
on OS
Snapshot
·
EBS volumes can be backed up
•
A point-in-time snapshot
·
Stored in S3
•
Provides very high durability
•
More on S3 shortly
·
Snapshots are incremental backups to reduce
storage requirements
•
Snapshots only store data that changed since
last snapshot
•
All snapshots have access to all data to restore
to that snapshot
•
Deleting a snapshot only deletes data unique to
that snapshot
·
A snapshot can be restored to a new EBS volume
Volume
Vs Snapshots
· Volumes
exist on EBS
o
Virtual Hard Disk
·
Snapshots exist on S3
·
You can take a snapshot of volume, this will
store that volume on S3.
·
Snapshots are point in time copies of Volumes.
·
Snapshots are incremental, this means that only
the blocks that have changed since your last snapshot are moved to S3.
·
If this is your first snapshot, it may take some
time to create.
Volumes
vs Snapshots - Security
· Snapshots
of encrypted volumes are encrypted automatically.
·
Volumes restored from encrypted snapshots are
encrypted automatically.
·
You can share snapshots, but only if they are
unencrypted.
o
These snapshots can be shared with other AWS
accounts or made public.
Snapshots
of Root Device Volumes
· To
create a snapshot for Amazon EBS volumes that server as root devices, you
should stop the instance before taking the snapshot.
RAID,
Volume & Snapshots
· RAID=Redundant
Array of Independent Disks
o
RAID 0 - Striped, No Redundancy, Good Performance.
o
RAID 1 - Mirrored, Redundancy
o
RAID 5 - Good for reads, bad of writes, AWS does
not recommend every putting RAID 5's on EBS
o
RAID 10 - Striped & Mirrored, Good
Redundancy, Good Performance.
How
can I take a Snapshot of a RAID Array?
· Problem
- Take a snapshot, the snapshot excludes data held in the cache by applications
and the OS. This tends not to matter on a single volume, however using multiple
volumes in a RAID array, this can be a problem due to interdependencies of the
array.
·
Solution - Take an application consistent
snapshot.
o
Stop the application from writing to disk
o
Flush all caches to the disk
·
How can we do this?
o
Freeze the file system
o
Unmount the RAID array
o
Shutting down the associated EC2 instances
Creating
Snapshots
·
Management Console
•
Three ways to create a snapshot
– From
EBS Volumes page, right-click volume and select Create Snapshot
– From
EBS Volumes page, select Actions | Create Snapshot
– From
EBS Snapshots page, select the Create Snapshot button
·
Command line:
·
Creating Snapshots
Syntax: #aws ec2 create-snapshot –-volume-id
<vol_id> –-description <description>
Example: #aws ec2 create-snapshot
–-volume-id vol-cf674da4 –-description "June05Snap"
Creating
Volumes from Snapshots
·
From Management Console
•
Can specify a snapshot when creating a new
volume (shown earlier)
•
Or
•
Same as before, except add a –-snapshot-id
parameter
# aws ec2 create-volume --size <size>
--snapshot-id <snapshot> --availability-zone <zone> --volume-type
<type>
Increasing EBS Volumes Size
·
A volume size cannot be increased directly, but
it can be done easily
·
Increasing volume size requires four steps
o
Create a snapshot of the volume
o
Create a new volume from that snapshot with a
larger size
o
Attach the new volume to an instance
o
Configure the file system for the new volume
size
– This
is the only new step
·
Performing Step 4 will depend on the operating
system
o
The following slides assume that a new 3-GB
volume was created from a 2-GB snapshot
Reducing EBS Volume Size
·
Reducing volume size is different than
increasing size
o
Volumes created from a snapshot cannot be
smaller than the snapshot
·
Reducing volume size is more of a manual process
·
Create a new EBS volume of the desired size
o
The new volume must be big enough to hold the
amount of data!
·
Attach both the original and new volume to the
same instance
o
Format the new volume as needed
·
Copy the contents from the original volume to
the new volume
o
Linux: Use cp or rsync
o
Windows: Use Windows Explorer or xcopy
·
Recommended to then create a snapshot of the new
volume
Moving EBS Volumes across Zones
Moving volumes across availability zones within the same region
is easy
·
Create a snapshot of the original volume
·
Create a new volume in a different zone from the
snapshot
o
Snapshots are not associated with an
availability zone
Moving EBS Volumes Across Region
·
Moving volumes across regions is also easy
o
Create a snapshot of the original volume
·
From the Snapshots screen, select the snapshot,
click Actions, and select Copy
o
Select the region to copy to
·
This will incur bandwidth charges
Encrypting EBS Volumes
·
EBS supports encrypting volumes
o
From the Create Volume screen, select “Encrypt
this volume”
§
Available keys are managed from the IAM console
·
Encryption/decryption performed by Amazon
·
Can also encrypt the volume manually
o
EBS volumes are just block-level devices
o
Can use operating system modules to encrypt
files or entire file systems
§
Windows Encrypting File System (EFS)
§
Various Linux/UNIX cryptographic file systems
EBS Limits
·
Each account has an EBS limit of a total size of
20 TB for each volume type
·
Higher limits can be requested at
o http://aws.amazon.com/contact-us/ebs_volume_limit_request
·
Requests are for a specific region
Exam Tips EBS
·
EBS Consists of;
o
General Purpose SSD - GP2 - (Up to 10,000 IOPS)
o
Provisioned IOPS SSD - IO1-(More than 10,000
IOPS)
o
Magnetic - cheap, infrequently accessed storage)
·
You cannot mount 1 EBS volume to multiple EC2
instances, instead use EFS.
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