AWS - EBS

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EBS definition

  • Network Block Storage
  • 5 9s availability
  • Attached to EC2 in same AZ
  • point-in-time backup to S3

Terminology

  • iops : transaction /sec
  • Throughput: read/write / sec
  • Latency: delay between request response
  • Capacity: Volumn size
  • Block size: size of each i/o (kb)

![GP2 Bursting Diagram][https://github.com/racheliurui/markdown/blob/master/AWS/AWS2018/images/extra_EBS_gp2.png?raw=true]

  • Scenario: boost time speed up for windows when using gp2 because of Bursting
    • which is important autosclaing
  • Database ( you can use 2 gp2 volumn to archive 2*3k iops)

History

With EC2 -> Magnet Storage -> SSD Storage -> gp2 SSD Storage -> Volumn Encryption -> Larger, faster -> Boot volumn encryption -> st1 and sc1 (HDD) -> EBS Elastic Volumns (2017)

IOPS vs Throughput

Select the correct type
IOPS: gp2 io1
Throughput: st1 sc1

EBS Elastic Volumns

Change:

  • You can increase volumn size (can’t decrease)
  • You can change volumn type
  • You can increase or decrease IOPS
  • You can combine above change together

Limitation:

  • change type must be valid , like size , st1 min size =500G, so we can’t change to st1 type with a size <500G
Type MinSize MaxSize Min IOPS Max IOPS Min Throughput Max Throughput
io1 SSD 1GiB 16TiB 100 3K
gp2 SSD 4GiB 16TiB 100 20K (50:1)
sc1 Magnet 500GiB 16TiB N/A N/A 12 192
st1 Magnet 500GiB 16TiB N/A N/A 40 500

How to modify elastic Volumns

  • Cli
cli
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aws ec2 modify-volumn
[--dry-run | --no-dry-run]
--volumn-id <value>
[--size <value>]
[--volumn-type <value>]
[--iops <value>]
  • other options: SDK, web console

Benefits

  • No performance impact
  • No Downtime
  • No over-provisioning

Steps

Step1 modify
Step2 Monitor

cli
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aws ec2 describe-volumes-modifications
[--volumn-ids <value> ]
[--filters <value>]
[--next-token <value>]
[--max-results <value>]

The status will show
“Modifying”–> “optimizing”–>“Completed”

Step3 Extend (if size is increased)

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lsblk
df -h
# ext2, ext3, ext4
sudo resize2fs device_name
# xfs
sudo xfs_growfs -d mount_point

On widows , run diskmgmt.msc and choose to extend volumns .

Limitation:

  • max 1 change every 6 hours
  • once modification request raise, you can’t stop it.
  • you can’t change the encryption mode for existing volumn

Bill

You are charged at the moment you trigger the request with the target volumn.

Best practise

  • Security: lock down the modify-volumn api , treat it as the same as delete volumn.

  • Test Test Test before make any change.

  • Use GP2 as boot volumn

  • Tag your EBS snapshot (always)

  • Your EC2 CPU / Memory should match provisioned EBS

  • SSD EBS read / write didn’t different in performance

  • use Cloudwatch to tuning EBS

  • Raid 0 (don’t use Raid 5 , or any raid with redundency)

  • Pre-warm : DD write for linux and NTFS Format; use big block to do pre-warm (like 1M)

  • try to use ext4 or XFS; alignment = 4k (???)

  • Refer to the cheetsheet for common use case

References

Dynamic EBS (2016)
https://youtu.be/9vhR41YTp7E

aws elastic volumns
https://github.com/aws-samples/aws-elastic-volumes

EBS Deep Dive (2015)
https://youtu.be/gUYa7RzrNhM

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