EBS is a network drive you can attach to ONLY ONE INSTANCE at any one time
important: EBS is not a network file system!
is bound to an AZ
think of it like a network USB stick
30GB per month free of type SSD or magnetic GP2 or GP3 volume
EBS can have some latency on the AWS network
can be detached from one EC2 and attached to another, eg for failovers, big advantage!
but cannot be moved to other AZs, unless you do a snapshot and then move.
have to provision in advance and the level of IOPS you want
you pay according to this after the first 30GB.
BUT you can have 2 EBS volumes attached to an EC2 – that is not limited.
however they are bound to an AZ
they can be attached on demand, do not have to be actively attached.
EBS Delete on Termination attribute – is enabled by default for EBS root volume
but not for other EBS volumes as it is disabled for the latter by default
you can change this…
advantage: to preserve root volume when EC2 instance is terminated.
You can transfer an EBS volume to another region or az by means of using snapshots.
You can move snapshots to archive which is much cheaper.
Snapshots are usually gone once deleted, but if you have recycle bin enabled then you can retrieve them for a limited time period according to retention rule you set.
EBS Volume Types
gp2 /gp3 SSD general purpose balances price/performance
io1/io2 SSD high performance for mission critical low latency/high throughput workloads
st1 HDD low cost HDD for frequently accessed throughput intensive workloads
sc1 HDD lowest cost HDD for less frequently accessed workloads
EBS volumes are by size, throughput, iops
NOTE: only gp2/gp3 and io1/op2 can be used as boot volumes
General Purpose SSD
system boot vols, virtual desktops, dev and test env
1GiB – 16TiB
3000 iops and 125 miB/s
can go up to 16k iops and 1000 MiB/s
small vols can do burst iops to 3000
size of volume and iops are linked max iops is 16k
3 iops per GB means at 5,334 GB we have max iops
Provisioned iops ssd
for critical biz apps with sustained iops performance
or apps that need more than 16k iops
good for db workloads
io1/io2 4GiB – 16TiB
max piops 64k for nitro ec2 and 32k for others
can increase piops indep of storage size
io2 gives more durability and more iops per gib
io2 block express 4gib – 64tib
very low latency
max piops 256k
cannot be a boot vol
125 mib to 16tib
throughput optimized hdd st1:
big data, data warehousing and log processing
max througput is 500 mib/s max iops 500
cold hdd sc1
for infreq accessed data
where low cost is important
max throughput is 250 mib/s max iops 250
you *dont* need to know these details for the exam, but be aware of the main difference in the variations
EBS Multi-Attach – for io1/io2 family
attaches same ebs volume to multiple instances in same az at same time
each instance has full r/w permissions to the vol
for high app availability in clustered linux apps eg teradata
apps must be able to manage concurrent write ops
only thus for very specific workloads,
you must use a cluster aware file system ie NOT ext4 xfs etc.
EFS Elastic File System
is a managed NFS-type system that can be mounted on multiple EC2s in multiple AZs.
highly available, scalable, but expensive, you pay per usage per gigabyte
web and data sharing, wordpress
uses security groups to control access
compatible only with linuxbased ami’s and not windows!
can enable enctryption at rest using kms
is a posix linux system with standard file api
scales automatically by itself!
efs performance and storage classes:
can support 1000s of concurrent nfs clients 10gb throughput
can grow to petabyle size automatically
– set at efs creation time
general purpose default – latency sensive use cases such as webserver, cms etc
to maximum i/o — gives higher latency, highly paralleluse for this io1 : this is best for big data applications, eg media processing etc
— bursting 1tb = 50mib/s and up to 100 mib/s
provisioned: set your throughput regardless of storage size eg 1 1gib/s per 1tb storage
EFS Storage Classes
you can set up storage tiers for lifecycle management
eg move to another tier after N days…
– standard tier – used for frequently accessed files
– infrequent access tier (IA) -efs-ia: costs to retrieve files
but lower price to store, enable efs-ia by means of a lifecycle policy
Availability and Durability of EFS
standard: can set up EFS to be multi AZ
one-zone: you use one AZ only, backups are default enabled, compatible with IA
90% cost saving
exam will ask you which tier /storage class you should use for which use case, and you need to be aware of the cost implications!
Differences Between EBS & EFS
must know for exam!
can only be attached to only one instance at a time
are locked into an AZ
gp2. io increases if disk size increase
io1: can increase the io independently.
to migrate an EBS across AZs
– take a snapshot
– restore the snapshot to the other desired AZ
note that ebs backups use up io and so you should not run them when your app has heavy traffic overhead
also, root ebs volumes get terminated by default if or when the ec2 instance gets terminated! very important to be aware of this
– but you can disable this
EFS by comparison:
can mount on 100
s of instances across AZs!
it is multi-AZ, multi-client/instance
can be used to share data
only available for linux posix, not windows!
efs more expensive than EBS but can use efs-ia to reduce costs
so: efs is more for multi instances
ebs is more for one instance
instance store: is an ephemeral local instance drive just for an instance – you lose it with the instance when the instance is deleted.