We a script to create couple of AMI, On successful completion of AMI it deletes the old AMI. As of my understanding AWS only charges for the space we use in S3 for storing snapshot that was created by an AMI.
If I created two AMIs for an instance on different dates(those two AMIs create two different snapshots). will they charge for only new snapshot size? or for the two snapshots?
How AWS charges for this process?
An Amazon Machine Image (AMI) is actually a standard EBS snapshot, with additional metadata.
EBS snapshots are incremental in nature, meaning that only blocks that have been added or changed are copied to Amazon S3.
This means that successive snapshots could incur very little additional cost. Imagine this scenario:
AMI 1 is created from an instance (or, more accurately, from the EBS volumes associated with the instance)
Some data is changed on the EBS volumes
AMI 2 is created from the instance
Since each AMI is a snapshot, and snapshots only copy incremental data to S3, then the additional cost for AMI 2 would only be the new/modified blocks.
If AMI 1 were then deleted, the cost drop would be minimal, since most blocks contained in the AMI 1 snapshot would be kept for the AMI 2 snapshot.
One interesting result of all this (which is merely my suspicion, since I could not find any official statement to this effect) is that, if your AMI is based off an existing volume (eg an AMI from Amazon), then any snapshots/AMIs created of that volume will actually inherit blocks that are part of the original snapshot. Therefore, you (probably) do not pay the full cost of storing that AMI since the snapshot points to blocks already in a snapshot originally created by Amazon. (Don't worry if you didn't understand all that!)
AMIs are stand alone in nature and treated individually no matter whether created out of the same instance on the same day. So they charges of the AMI storage would be calculated 2 times.
For the record the AMI creation involves the snapshotting behind the scenes and AWS performs those snapshots calculating the delta; so the AMI creation process would faster the second time but still they are treated a 2 individual copies.
Related
Actually I have to take forecast of costing for one my instance, which is having a number of volumes attached... These volumes are different in size and types.
Let's suppose I took the AMI backup and terminated the server.
Now my confusion is how would I calculate the cost. The cost will be calculated based on pricing of Amazon EBS Volumes or Amazon EBS Snapshot. Because the cost difference is just double.
Let me know if you can help me understanding.
pricing of Amazon EBS Volumes or Amazon EBS Snapshot Which I took from AWS Pricing :
https://aws.amazon.com/ebs/pricing/
Amazon EBS snapshots are a complex subject due to the way they work.
There is a detailed explanation in: Amazon EBS snapshots - Amazon Elastic Compute Cloud
A quick summary is:
Snapshots contain only the data that is different to previous snapshots (they are incremental)
An AMI is actually a snapshot. So, if you booted a new Amazon EC2 instance from an AMI and then created a snapshot, the snapshot would contain very little since most of the volume was already contained in the previous snapshot (that was part of the AMI). Confused yet?
Any snapshot can be deleted and information will still be retained to allow any other snapshot to be restored. So, the snapshot is actually an 'index' to the snapshot data, and the snapshot data is stored separately to the snapshot itself. You should be questioning your sanity at this point!
So, the cost of Amazon EBS snapshots is mostly based on how much the contents of the volume changes, and how many snapshots (effectively, points-in-time) you wish to keep. If you only keep the most recent snapshot, then all data will be available, but the cost will be minimised because it won't keep any data that has been deleted from the volume.
Bottom line: Snapshots take less space than the data on a volume due to the incremental natures. The more snapshots ("points-in-time"), the more data will be kept and hence the more cost.
I am trying to create a AMI from an instance with a root device of 160GB in size. This root volume is of type io1 with an iops of 1250.
In my AWs account, creating an AMI takes about 5 minutes. This is with data about more than 100GB.
On the customer's AWS account, the same configuration takes over 20+ minutes.
I have tested this with many repetitions and I get almost similar results all time.
Any idea why the AMI creation varies so much between multiple AWS accounts?
An AMI consists of snapshots of Amazon EBS volumes attached to the instance.
Snapshots consist of "differences" from the previous snapshot (including the original AMI that was used to launch the instance).
For example, if you were to launch a new instance from an AMI and then immediately create a new AMI from the instance, very little data would have changed on the disk volume. Thus, the AMI and its underlying snapshot would be very quick to create.
If, over time, a lot of information was added/modified on the disk volume(s), then creating an AMI will take longer because more disk blocks have changed.
Creating Snapshots and AMIs can be made faster by taking more frequent snapshots, since this will copy modified blocks to Amazon S3. Thus, each successive snapshot/AMI will require fewer blocks to be copied.
The speed of a snapshot/AMI is not impacted by the assigned IOPS to a volume. The snapshot process takes place in the back-end, which does not consume the IOPS allocated to a volume.
I am Using ec2 and creating a custom AMI using a snapshot for my machine. I Can't find how to get it's actual size on disk to calculate the cost it will charge me to store it.
How can I get the actual compressed size or estimated cost for storing an AMI (snapshot of a machine)
AMI sizes are not easy to calculate. This is because they are based on Amazon EBS snapshots, and EBS snapshots are incremental in nature.
For example:
Let's say you launch an instance from an Amazon Linux AMI
You then login and create a file on the disk
You then create a new AMI
Any blocks that have been added or changed (eg for the new file on the disk) will be included in your AMI (or, more accurately, in the snapshot that stores the AMI data). However, all the blocks that were not modified from the original AMI are not stored in your AMI. Instead, the AMI will contain a reference to the blocks in the original AMI. This is due to the incremental nature of snapshots.
So, the reality is that most of an AMI (most of a snapshot) actually contains pointers to existing data and it therefore is not charged to you. You will only pay for storage that does not already exist.
That's why you can't really get the storage size of an AMI.
The only way to know the storage size for sure would be to create a totally new AMI that is not based on an existing AMI, since you would then be charged for the total size. (I wouldn't recommend doing so.)
i m running ec2 instance in 1 region i want to create snapshots of ec2 instances in other region directly without coping and cross region replication in s3, is this possible? if possible then how?
Amazon EBS Snapshots are created in the same region as the original EBS Volume. They can then be used to create a new Volume within the same Region.
If you wish to use an Amazon EBS Snapshot in a different region, the snapshot must first be copied to the other Region. This can done via the Amazon EC2 management console, the AWS Command-Line Interface (CLI) aws ec2 copy-snapshot command, or an AWS API call.
Please note that snapshots are incremental backups. The first snapshot isn't really a full backup. Rather, every snapshot simply copies any blocks that have been modified since any previous snapshot. Blocks are retained while snapshots still require the blocks. This means that blocks made during the initial snapshot could actually be deleted if they are not required by any active snapshots. This is why I say they are not the same as a full backup, which traditionally never has content deleted.
However, when a snapshot is copied to a new region it is copied in full, rather than incrementally.
If you do not with to copy an EBS snapshot between regions, you would need to find a different way to transfer the disk volume (eg filesystem-level synchronisation).
In fact, there should typically be no need to transfer a disk volume -- rather, your systems should be capable of configuring a new server based upon a startup configuration script and data should be stored in a separate database so that it is accessible to multiple instances. It is a very rare case that requires a complete copy of a disk volume.
I am trying to create a backup mechanism for our server, so that if my system crashes, I should be able to create the whole system by running a single script
After going through Amazon documentation, this is my understanding of creating a backup and restoring
Backup
Create a AMI Image (this can be updated monthly)
Create a snapshot (This can be done using a daily script creating a snapshot)
Restore (A script to)
Create an EBS instance using AMI
Attach the EBS volume to Instance created
Now my Questions are
Is it the best way to take a backup and restore?
Do we actually need to backup 2 things, AMI and EBS volume (using snapshot), Can we just keep snapshots?
I understand this cannot work for a local instance store instance, as there is no snapshot functionality. So how can I create a backup and restore process for local instance store instances?
As I could not find any better alternative, I am sticking with the initial approach.
For EBS
Backup:
Create a AMI Image (this can be updated monthly).
Create a snapshot (This can be done using a daily script creating a snapshot).
Restore (A script to)
Create an EBS instance using AMI.
Attach the EBS volume to Instance created.
For instance store, I am only keeping the application (no database), so no need to keep a backup of that.
EBS Snapshots are an excellent way to create backups.
You can perform frequent Snapshots of your EBS Volumes via scripts. Weekly, Daily, Hourly, or as frequently as your Credit Card will allow. The only limit is around how many simultaneous snapshots you can be doing - when you hit that, the EBS API will start giving back errors until a few of the in-flight operations complete.
Snapshots can also be copied from Region to Region in order to provide backup against a catastrophic event.
When you snapshot an EBS volume, that snapshot is of the entire volume. Even if it was created from an AMI, your snapshot contains everything you need to create a new instance of the volume. You can pretty easily try this yourself.
If your instances are Linux based, there is no need to create an AMI if you're taking snapshots. You can create the AMI on the fly, from the snapshots, when you need to recover. If you got that process automated, it's pretty easy to do.
In Windows there is a limitation not allowing to launch an EC2 instance from a snapshot, so AMIs must be used. There are ways to workaround that limitation: You can check out the this post I wrote in our company's blog:
http://www.n2ws.com/blog/3-ways-ec2-windows-backup-and-recovery.html
I would suggest to use Auto Scaling in addition to EBS snapshots. If Instance is dying because of Hardware failure or it's scheduled for retirement by Amazon, Auto Scaling will start new Instance automatically.
But in this case, you have to setup NAS for your dynamic data. Depending on Server Load, the number of running Instances will be different and all your scaling servers must mount NAS storage which is shared across them.
Your Database should be on separate server or servers as well. Or you might want to use Amazon RDS as it has great auto-backup / Point-In-Time-Restore features, but you have to pay extra for that.
1) Yes.Snapshot is best way to backup and restore EBS volumes.
2) Depends, if you have the root volume as EBS backed AMI, then you can snapshot them as well and improves the manageability
3) Rsync and AMI is the option available for instance store