Instance Storage

It’s a disk physically connected to the host.

The data is lost whenever you stop or terminate the instance, but persists if the instance reboots.

  • Scope: server ()
  • Not persistent
  • Low latency
  • High IOPS

Suggested for cache, buffers, scratch data and other temporary data.

AWS recommends keeping the number of directories on your file system to less than 10,000, if possible.

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Amazon Elastic Block Store (EBS)

EBS volumes are automatically replicated in the same AZ of the EC2.

EBS volumes can be encrypted using industry-standard AES-256 keys generated by AWS KMS.

  • Scope: AZ
  • Availability 5 9s
  • Durability .1% to .2%

EBS Snapshots

To increase durability you can use PIT Snapshots, that are replicated across multiple AZs in the region. These sanpshots can be used to create new volumes.

If there’s an accidental delete or other application error, snapshots enable you to recover your data.

  • Scope: Region (S3)
  • Availability 4 9s (S3)
  • Durability 11 9s (S3)

  • To increase resilience = custom solution multi backup, multi region, multi account

  • Snapshots that are taken from encrypted volumes are automatically encrypted
  • Volumes that are created from encrypted snapshots are also automatically encrypted
  •  To share an encrypted snapshot:
    • You must also share the CMK key that was used to encrypt it
    • External users must create their own personal copy of it and then use that copy

When you create an EBS volume from a snapshot, data is lazy loaded into the volume, meaning that if the volume is accessed where data is not loaded, the application encounters a higher latency than normal.

EBS Snapshots Archive

Low-cost, long-term storage tier for rarely-accessed snapshots.

When you archive a snapshot, the incremental snapshot is converted to a full snapshot, and it is moved from the standard tier to the Amazon EBS Snapshots Archive tier.

When you need to access an archived snapshot, you can restore it from the archive tier to the standard tier, and then use it in the same way that you use any other snapshot in your account.

Multi-volume snapshots

  • Point-in-time snapshots for all, or some, of the volumes attached to an instance
  • Each snapshot is treated as an individual snapshot
  • Multi-volume, crash-consistent snapshots are typically restored as a set
  • It’s a good idea to identify the snapshots that are in a crash-consistent set by tagging them with the instance ID, name, or other relevant details

EBS Data Lifecycle Manager (DLM)

Provides a simple, automated way to back up data stored on Amazon EBS volumes.

  • Automated snapshot and AMI creation
  • Fast snapshot restore integration Restore volumes that are fully initialized at creation
  • Built-in cross-Region copy
  • Automated cross-account snapshot copy

    RAID

    EBS Striped volume = Raid 0
    EBS Mirror = Raid 1

EBS Volume Status checks

  • Any volume type
    • ok
    • warning
    • impaired
    • insufficient data
  • Provisioned IOPS SSD
    • Normal
    • Degraded
    • Stalled
    • Insufficient data

EBS Types

SSD-based volumes - General purpose

Balance price and performance, recommended for most workloads.

  gp2 gp3
Use cases Boot volumes,
low-latency interactive apps,
dev & test		 as gp2 +
medium sized
single instance databases
Volume size 1 GB – 16 TB ’’
Durability 99.8% - 99.9% ’’
Baseline IOPS 3 IOPS/GB
(minimum 100 IOPS)		 3,000 IOPS at any size
Max IOPS/volume 16,000 ’’
Burst up to 3,000 IOPS no burst
Max Throughput/volume 250 MB/s 1000 MB/s
Max IOPS/Instance 260,000 ’’
Max Throughput/Instance 7,500 MB/s 12,500 MB/s
Latency single digit ms ’’
Price (GB/month) $0.10 $0.08
Dominant performance attribute IOPS $/IOPS

SSD-based volumes - High performance

Highest performance, for mission-critical low-latency or high throughput workloads (large databases).

  io1 io2 Block Express
Use cases I/O-intensive
NoSQL &
relational databases		 business-critical
’’
Volume size 4 GB – 16 TB 4 GB – 64 TB
Durability 99.8% - 99.9% 99.999%
Max IOPS/volume 64,000 256,000
Max Throughput/volume 1,000 MB/s 4,000 MB/s
Max IOPS/Instance 400,000 ’’
Max IOPS/GB 50 IOPS/GB 1,000 IOPS/GB
Max Throughput/Instance 12,500 MB/s ’’
Latency single digit ms sub-millisecond
Price (GB/month) $0.125 $0.125
Price (Provisioned IOPS-month) $0.065 $0.065 (first 32,000)
$0.046 (32,001 to 64,000 IOPS)
$0.032 (greater than 64,000 IOPS)
Dominant performance attribute IOPS IOPS, throughput, latency,
capacity, and volume durability

HDD-based volumes

Lowest cost volumes, for less frequently accessed workloads.

  sc1
Cold HDD		 st1
Throughput optimized HDD
Use cases Colder data
requiring
fewer scans per day		 Big data,
data warehouses,
log processing
Volume size 125 GB – 16 TB ’’
Durability 99.8% - 99.9% ’’
Max IOPS/volume 250 500
Baseline throughput 12 MB/s per TB 40 MB/s per TB
Max Throughput/volume 250 MB/s 500 MB/s
Burst up to 80 MB/s per TB up to 250 MB/s per TB
Max Throughput/Instance 7,500 MB/s 12,500 MB/s
Latency single digit ms  
Price (GB/month) $0.015 $0.045
Dominant performance attribute MB/s ’’

EBS Multi-Attach

Multi-Attach makes it easier to achieve higher application availability in applications that manage concurrent write operations. You can enable Multi-Attach during volume creation.

  • Works only with io1 or io2 volumes
  • Instances must be in the same AZ
  • Each instance has full read/write permission
  • Standard file systems, such as XFS and EXT4, are not designed to be accessed simultaneously by multiple servers. You should use a clustered file system to ensure data resiliency and reliability for your production workloads.
  • Multi-Attach enabled volumes can’t be created as boot volumes

EBS Elastic Volumes

You can increase the volume size, change the volume type, or adjust the performance of your volume without detaching it or restarting the instance. This enables you to continue using your application while the changes take effect. There is no charge to modify the configuration of a volume.

  • Supported by all current generation instances, and some of previous ones
  • After modifying a volume, you must wait at least 6 hours
  • The change can take from a few minutes to a few hours, depending on the configuration changes being applied. The time it takes for volumes to be modified doesn’t always scale linearly.

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Amazon Elastic File System (EFS)

Simple, scalable elastic file system for linux that can be mounted concurrently through NFSv4.

  • Scope: Region
  • Availability: 3 9s —> Lower availability than EBS
  • Durability: 11 9s —> Higher durability than EBS
  • Replicato in modo sincrono in due istanze nella AZ
  • Up to 3GB/s throughput (in some regions is 1GB/s)
  • 250MB/s per client
  • Latency: unpublished but can be 1ms

Tenere d’occhio la metrica di BurstIO, se scende a zero per un alto numero di client ci sarà un crollo delle prestazioni.

EFS Types

General purpose performance mode

  • 7000 IOPS
  • Lowest metadata latency

MaxIO performance mode

  • 500.000+ IOPS
  • Highest metadata latency

Performance is impacted by:

  • File system type – Regional or One Zone
  • Performance mode – General Purpose or Max I/O (General Purpose gives faster performance!)
  • Throughput mode – Elastic, Provisioned, or Bursting

Storage classes

  • EFS Standard
    • Uses solid state drive (SSD) storage to deliver the lowest levels of latency for frequently accessed files
    • Provides first-byte latencies as low as 250us for reads and 2.7ms for writes.
  • EFS Infrequent Access (IA) and EFS Archive
    • Less frequently accessed data that doesn’t require great latency performance
    • Provide first-byte latencies of tens of milliseconds.

Performance modes

  • General Purpose mode
    • Lowest per-operation latency
    • Default performance mode for file systems
    • One Zone file systems always use the General Purpose performance mode.
    • Recommended for faster performance
  • Max I/O mode
    • Previous generation performance type
    • Designed for highly parallelized workloads that can tolerate higher latencies
    • Not supported for One Zone file systems or file systems that use Elastic throughput

Throughput modes

Your file system can achieve a combined 100% of its read and write throughput.

  • For example:
    • if your file system is using 33% of its read throughput limit
    • the file system can simultaneously achieve up to 67% of its write throughput limit.
  • Elastic throughput (Recommended)
    • Default
    • When you have performance requirements that are difficult to forecast
    • When your application drives throughput at an average-to-peak ratio of 5% or less
  • Provisioned throughput
    • When you know your workload’s performance requirements
    • When your application drives throughput at an average-to-peak ratio of 5% or more
  • Bursting throughput
    • When you want throughput that scales with the amount of storage in your file system
AWS Study Guide
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