Obviously, hibernation and stop are two different actions that I can select.
What's the difference?
Benefit of Hibernating over Stopping
The memory state is preserved
Since the memory state is perserved and loaded again when the instance start, this reduce the boot time of the instance.
The long running process can continue without interuption
A great benefit if you have some services that take a great amount of time to fully initialized
Under the hood
The whole hibernation process in visual:
When the instance is in Stopping state, the instance memory is persisted in the instance's EBS root volume, and is loaded again when the instance start.
Reference
AWS Instance Hibernate Overview
From the docs
When you hibernate an instance, Amazon EC2 signals the operating
system to perform hibernation (suspend-to-disk). Hibernation saves the
contents from the instance memory (RAM) to your Amazon Elastic Block
Store (Amazon EBS) root volume. Amazon EC2 persists the instance's EBS
root volume and any attached EBS data volumes. When you start your
instance:
The EBS root volume is restored to its previous state
The RAM contents are reloaded
The processes that were previously running on the instance are resumed
Previously attached data volumes are reattached and the instance retains its instance ID
Read more
TL;DR
When you stop your instance, the data stored in memory (RAM) is lost.
When you stop-hibernate an instance, AWS signals the OS to perform hibernation (suspend-to-disk), which saves the contents from the instance memory (RAM) to the Amazon EBS root volume.
From the charging perspective, AWS does not charge usage or data transfer fees for your instance after you stop it, but storage for any Amazon EBS volumes is still charged.
A practical example
Suppose you want to build a caching layer (e.g. on top of your DB) in an EC2 instance. For such a case, the stop-hibernate feature would be instrumental in persisting storage. It would prevent you from having to manually create scripts to save the RAM data before shutting down the server.
Related
Using ec2 Windows instance with Instance storage (let's say 32GB SSD) - where OS and its settings are stored? Like Program Files, User profiles. Are they all stored on Instance Storage? As far as I understood from other topics Instance storage is not-persistent and doesn't survive shutdowns/terminations. Does that mean I will lose everything under C: drive if I turn it off?
Can I use EBS storage as a default storage for OS (C drive)? Can I map multiple EBS storages to one Windows storage?
If above is true, then I will be charged for the capacity used by OS on EBS instance? It would be around 20GB I believe. Is that correct?
I am quite new in aws, and before paying for such instances or EBS I would like to know how this technical and billing model is working.
Thank you!
The Storage for the Root device is dependent on the AMI (EBS-Backed or Instance Store-Backed) used to launch the instance.
As far as I understood from other topics Instance storage is
not-persistent and doesn't survive shutdowns/terminations.
If the Root storage device is Instance Store, Stopping (shutdown) the instance is not possible. On termination, Both the storage and Instance does not survive. The Instance does not survive once terminated even if the AMI is EBS-Backed, but you can persist the Root Volume by setting the DeleteOnTermination flag set to False.
Does that mean I will lose everything under C: drive if I turn it off?
You cannot turn off (shutdown) an Instance Store-backed instance.
Can I use EBS storage as a default storage for OS (C drive)?
Yes, Choose an EBS backed Windows AMI.
Can I map multiple EBS storages to one Windows storage?
Yes, multiple EBS Volumes can be attached to one EC2 Windows Instance.
If above is true, then I will be charged for the capacity used by OS
on EBS instance?
You will be charged for the total size of the EBS volumes attached to the instance including the Root Device.
It would be around 20GB I believe. Is that correct?
The EBS Volume Size is adjustable. The upper Size limit is 16TiB.
Read Storage for Root Device and Ec2 Root Device Volume
Please spend more time on the AWS documentation, I don't think here is enough to cover all your question.
Only for specify EC2 instance come with attached SSD storage AKA instance storage. Bare in mind that, this instance storage doesn't come with Snapshot capabilities, so you must backup the file yourself. This is mean for people who need fastest disk access to process their data.
Only EBS allow you do multiple snapshot.
You can always create an AMI image for your instance after complete the deployment. AMI image is store inside EBS, so you will not lost the initial instance if you do this, so for new instance, you just trigger load it from AMI.
If you "Terminate" an instance, it will delete the virtual image. There is no way to recover it even with EBS, unless you make a snapshot. However, attached EBS storage will not be deleted.
EBS is calculate by Per GB and give you 1GB x 3 IOPS, with base 100 IOPS given. This is not enough if anyone want to carry out disk I/O intensive task.
I'm using an EC2 instance on amazon and have mounted a 1TB ephemeral to the instance. The instance is an on-demand instance that costs $5 an hour. I was wondering whether there is anyway that I could stop (not terminate) the instance and still keep my data on the mounted ephemeral drive?
The Amazon EC2 Instance Store documentation says that if I stop it, I will lose the data. Does anyone have a solution?
Instance Store is disk storage directly-attached to the Amazon EC2 host machine. When an EC2 instance is Stopped, the virtual machine is removed and it loses the CPU, RAM and Instance store so that it can be allocated to another user.
Data saved on Amazon EBS disk volumes are retained because this is network-attached storage that is kept separate from the Host computer.
The only way to "save" your data is to copy it to another location (eg an EBS volume or Amazon S3 bucket) before stopping the instance.
You can use Amazon Elastic Block Store volumes for an ec2 instances. Once you stopped your instance, ebs volumes will retain the data. You can take snapshots on your ebs volume by specific time or incremental snapshot based on your requirement. BTW, You can store the snapshot in AWS S3 bucket for backup purposes. You can copy snapshot to different region via AWS Management Console or AWS API calls.
If you choose instance store volume type, you will lose your data. For persistent disk storage you can choose AWS EBS volumes.
I am new to AWS functionality and is confused in these 3 things.
To me if I consider
Memory as the RAM
Instance Storage as the hard disk space
then what is size and volume type means?
When you launch an instance on EC2, Amazon has to look for a physical server that will host your instance with enough unallocated capacity to be able to run your instance.
In the case of an m1.medium instance, this physical host would need to have enough unallocated resources so that the m1.medium instance specs would fit into it:
at least 1 unallocated core
at least 3.7 GiB of unallocated RAM
at least 1 disk with 410 GiB of unallocated space
So, from this description you see that "Memory" is the amount of RAM and "Instance Storage" is the amount of disk space inside the physical host that is running your instance.
Note that, I insist, this "Instance Store" is disk space local to the physical host. What does this imply? Well, if you stop the instance, you will deallocate all those resources so that another customer can use them. This means that you will deallocate the cores, the RAM and the disks. Which means the data saved on Instance Store is lost when you stop/terminate the instance, or whenever the physical host running the instance fails for whatever reason ("Everything fails, all the time" -- Werner Vogels, CTO at Amazon). This is why Instance Store is called ephemeral storage.
If you want persistent storage, then you'd need to use a service called Amazon EBS -- Amazon Elastic Block Store. In EBS, you create volumes. EBS Volumes are a kind of network attached storage. You can attach a Volume to any EC2 Instance in the same Availability Zone, then you can detach without losing data, then attach to another instance, and so on. When you stop an Instance, you don't lose data stored on EBS Volumes -- this is why they are called persistent storage.
In the screenshot in your question, what you see is that the Root volume (i.e., the "disk" where your operating system will be running) is an standard EBS volume (there's another kind of EBS volume, called PIOPS). This implies that any OS settings you change (and save to the root volume) will be persisted and survive an stop-start sequence, or instance restarts due to crashes.
There are some AMIs (Amazon Machine Images) that use Instance Store as the Root Volume. Instances launched with those AMIs won't persist any changes to the OS settings that are saved to the root volume -- therefore, if you stop them and start them again, you'd get a fresh OS.
I hope this answers your questions.
I thought I clearly understood the difference between instance-store and EBS backed AMIs.
But http://aws.amazon.com/maintenance-help/ says "if you are running an EBS-backed AMI, you can stop and then restart your instance in order to easily re-launch it. This will cause the loss of any data you have saved on the local instance store of the instance,"
Stop/start does NOT lose the sysvol data, so this confuses me.
I'm assuming that here, by "local instance store", they mean the backing EBS volume (the sysvol), and I'm thinking that they meant to say "terminate" instead of stop. Am I correct?
Terminating an EBS-backed instance will not cause your data to be deleted. You can still access the EBS volume until you delete it (unless you set it to delete when your instance is terminated).
Local instance store refers to hard drive space on the actual physical server that is running your instance. You can see the available instance store by doing sudo fdisk -l. Some images come with some instance store volumes already mounted (see df -h). Otherwise you'll have to mount and format the instance store volumes before you can use them.
Data on an instance store volume is lost when you stop (not terminate) your instance because it is local to a physical server, and your instance might start up on a new server.
Quite simply, EC2 is running your virtual server on some physical server. The root filesystem can either be on a local disk (ephemeral storage) or on network attached storage (EBS). With EBS, they can snapshot it for backups or to make a copy, so EBS is far more flexible, although not as fast as a local disk in the server where your instance is running.
In order to make this all work, when you shutdown an ephemeral server, amazon wipes the disk in order to reallocate it to the next customer. There is no need or reason for them to do that with EBS, since it was not physically attached to that server in the first place.
You might note, that even EBS backed instances (depending on size) come with an allocation of ephemeral storage (2-500gig+) which can be used for swap, logs, or whatever else you want to do with them. The only issue of course is that should the server be shutdown, or should there be a catastrophic disk or hardware error, you'll lose that data. You can still manually back it up, in the same way people have backed up traditional servers over the years.
Making your own AMI from an EBS backed server is trivial now, and can be done easily through the AWS web interface. Making a non-EBS backed AMI is a very complicated task the last time I tried to do it. With that said, there are certain use cases where it makes a lot of sense to consider using purely ephemeral storage. Computation or memory/cache nodes that have no need to persist data will be faster and cost less.
I am trying to stop a Amazon EC2 instance and get the warning message
Warning: Please note that any data on the ephemeral storage of your instance will be lost when it is stopped.
My Question
What data is stored in ephemeral storage of an Amazon EC2 instance?
Basically, root volume (your entire virtual system disk) is ephemeral, but only if you choose to create AMI backed by Amazon EC2 instance store.
If you choose to create AMI backed by EBS then your root volume is backed by EBS and everything you have on your root volume will be saved between reboots.
If you are not sure what type of volume you have, look under EC2->Elastic Block Store->Volumes in your AWS console and if your AMI root volume is listed there then you are safe. Also, if you go to EC2->Instances and then look under column "Root device type" of your instance and if it says "ebs", then you don't have to worry about data on your root device.
More details here: http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/RootDeviceStorage.html
Anything that is not stored on an EBS volume that is mounted to the instance will be lost.
For example, if you mount your EBS volume at /mystuff, then anything not in /mystuff will be lost. If you don't mount an ebs volume and save stuff on it, then I believe everything will be lost.
You can create an AMI from your current machine state, which will contain everything in your ephemeral storage. Then, when you launch a new instance based on that AMI it will contain everything as it is now.
Update: to clarify based on comments by mattgmg1990 and glenn bech:
Note that there is a difference between "stop" and "terminate". If you "stop" an instance that is backed by EBS then the information on the root volume will still be in the same state when you "start" the machine again. According to the documentation, "By default, the root device volume and the other Amazon EBS volumes attached when you launch an Amazon EBS-backed instance are automatically deleted when the instance terminates" but you can modify that via configuration.
To be clear and answer #Dean's question: EBS-type root storage doesn't seem to be ephemeral. Data is persistent across reboots and actually it doesn't make any sense to use ebs-backed root volume which is 'ephemeral'. This wouldn't be different from image-based root volume.
For EC2 instance
Stop & Start != Reboot
so for ephemeral storage (Instance Store)
Stop cause data lost
Reboot will not
According to AWS documentation [https://aws.amazon.com/premiumsupport/knowledge-center/instance-store-vs-ebs/] instance store volumes is not persistent through instance stops, terminations, or hardware failures.
Any AMI created from instance stored disk doesn't contain data present in instance store so all instances launched by this AMI will not have data stored in instance store. Instance store can be used as cache for applications running on instance, for all persistent data you should use EBS.
ephemeral is just another name of root volume when you launch Instance from AMI backed from Amazon EC2 instance store
So Everything will be stored on ephemeral.
if you have launched your instance from AMI backed by EBS volume then your instance does not have ephemeral.
refer: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html#instance-store-volumes
The data in an instance store persists only during the lifetime of
its associated instance. If an instance reboots (intentionally or
unintentionally), data in the instance store persists. However,
data in the instance store is lost under any of the following
circumstances:
- The underlying disk drive fails
- The instance stops
- The instance hibernates
- The instance terminates