Is EFS a substitute of HDFS for distributed storage? - amazon-web-services

Our business requirement is to read from millions of files and process those parallelly (later index those in ES). This is a one time operation and after processing those we won't read those million files again. Now, we want to distribute the file storage and at the same time ensure data retention. I did some research and made the list
EBS: The data is retained even after EC2 instance is shut down. It is accessible from a single EC2 instance from our AWS region. It will be useful if we split the data on our own and provide it to different EC2 instances. It offers redundancy and encryption security. Easy to scale. We can use it if we divide the chunks manually and provide those to the different servers we have.
EFS: It allows us to mount the FS across multiple regions and instances (accessible from multiple EC2 instances). Since EFS is a managed service, we don’t have to worry about maintaining and deploying the FS
S3: Not limited to access from EC2 but S3 is not a file system
HDFS: Extremely good at scale but is only performant with double or triple replication. Scaling down HDFS is painful and buggy. "It also lacks encryption at storage and network levels. It has also been connected to various controversies because cybercriminals can easily exploit the frameworks that are built on Java." Not sure how big of a concern this is considering our servers are pretty secure.
Problem with small files in Hadoop, explained in https://data-flair.training/forums/topic/what-is-small-file-problem-in-hadoop/ Considering most of the files we receive are less then 1 MB; this can cause memory issues if we go beyond a certain number. So it will not give us the performance we think it should.
My confusion is in HDFS:
I went through a lot of resources that talk about "S3" vs "HDFS" and surprisingly there are no clear resources on "EFS" vs "HDFS" which confuses me in understanding if they are really a substitute for each other or are complementary.
For example, one question I found was "Has anyone tried using AWS EFS mounts as yarn scratch and HDFS directories?" -> what does it mean to have EFS mount as HDFS directory?
"Using EBS volumes for HDFS prevents data locality" - What does it mean to use "EBS volume" for HDFS?
What does it mean to run "HDFS in the cloud"?
References
https://databricks.com/blog/2017/05/31/top-5-reasons-for-choosing-s3-over-hdfs.html
https://cloud.google.com/blog/products/storage-data-transfer/hdfs-vs-cloud-storage-pros-cons-and-migration-tips
https://www.knowledgehut.com/blog/big-data/top-pros-and-cons-of-hadoop
https://data-flair.training/blogs/13-limitations-of-hadoop/

There are possibilities by any kind of storage but as your situation is a one time scenario you need a choice with respect to
Cost optimized
well Performed
Secure
I can not answer to all your questions but concerning your use case I consider you use reach the data from EC2 instance and if you had mentioned the producing and processing of these files and the size of each file approximately maybe I could help you better.
Considerations:
EBS has a provisioned or limited Throughput and force you to provision and remove the data after treatment. FYI: you can set retention policy of EBS volume to be deleted by EC2 termination but not on shutdown.
If you need really the fastest way and don't care about costs EBS is a good idea with a good provisioning as you are charged by their life and storage.
EFS is a NAS storage and also needs the data be removed after treatment.
HDFS is a distributed file system and is the best choice for petabyte and distributed file systems but is not used as a one shot solution, you need installation and configuration.
I propose you personally the S3 as you does not have a limited throughput and using VPC endpoint you can achieve up to 25 Gbps, alternatively you can use the S3 life cycle policies to remove your data automatically based on tags or after 1 up to 356 days or archive them if needed.

Related

Syncing remote folders from several machines to one AWS instance

I have 3 AWS P instances processing some heavy stuff and saving results to relevant /home/user/folder
Also I have a main server with the same folder where I want to collect results from those 3 instances
Each instance works on its own part of the whole task, their results in sub folders not overlapping
Instances are 2 TB each, so I would like to get results from each instance as soon as they appear
This way when its job is done, I won't spend half a day copying results to the main server
I think one way of solving this is running something like this on each instance:
*/30 * * * * rsync /home/user/folder ubuntu#1.1.1.1:/home/user/folder
Are there any other more smart ways of achieving same results given that all of instances are AWS?
I also thought about (1) detachable storage and (2) storing on S3 but being new to AWS I might overlook some hidden pitfalls in such workflows, especially when it comes to terabytes of data and expensive instances.
How do you collect processed data from remote instances?
I would consider using rclone tool, which can be easy configured for the shared S3 bucket. Just be aware about copy/sync mode. It can rich up to several Gigabit throughput depending on your instance type.
Link for the project: rclone.org
My thoughts on some of the options mentioned in OP and comments, as well as some other ones I thought of:
EFS: create an EFS and mount it as an NFS drive on all the instances. It's the easiest but probably costs the most.
s3fs: have all the instances mount the same S3 bucket using s3fs. This is likely the most inexpensive solution. You also don't need to worry about running out of disk space. The downside is that the performance is not going to be that good compared to mounted NFS drives.
EBS volumes: attach an EBS volume to each worker instance for them to write the results to. When they are done, detach the volumes and attach them to the main server. This will be the fastest and still cheaper than EFS. If you can't or won't do all the detaching/attaching manually you'll need to write some scripts.
Old school NFS shares: there is nothing wrong with a plain vanilla NFS setup without any of those fancy AWS acronyms. :-)

Loading large amount of data from local machine into Amazon Elastic Block Store

I am interested in doing some machine learning using an AWS EC2 instance. I have played around with launching instances with a an attached EBS and I was able to load files into it via scp on my local command line. I will have several gigabytes of data to load onto this EBS (I know that isn't a lot by ML standards but that's not really my point). I would like to know what is the appropriate way to load this data. I'm concerned about racking up large fees because I did something in a silly way.
So far I have just uploaded a few files to the EC2 instance's associated EBS manually via the command line, like this:
scp -i keys/ec2-ml-micro2.pem data/BB000000001.png ubuntu#<my instance ip>:/data
This seems to me to be a rather primitive approach (not that that is always a bad thing). Is it the "right" way? I'm not opposed to letting a batch jbb run overnight like this but I am not sure if it may incur some data transfer fees. I've looked around for information on this, and I have read the page on EBS pricing. I didn't see anything on costs associated with loading data but I just wanted to confirm with someone or some people who have done something similar that this is the correct approach, and if not, what is a a better one
In managing large objects in AWS. Always check for S3 as an initial option, it provides unlimited Storage capacity and best use for object store compared to EBS(block store). EBS billed you from the size of the volume that you provisioned, having said that there is a chance that you over-provisioned(overhead cost) or under-provisioned (can lead to poor performance or even downtime).
Using S3 you are billed for the storage that you consumed per GB per month, pay for what you use model and it's very cheap compared to EBS.
And lastly, try to evaluate first the AWS Machine Learning services that might fit for your use-cases it will save you alot of time and effort.
Data Transfer from S3 to EBS within the same region is free of charge.
AWS Pricing Details

Which AWS services and specs should I best use for a file sharing web system?

I'm building a web system where 100-150 users will keep uploading/downloading ~10 GB total worth of audio files everyday (average of 150 total uploads and 250 total downloads per day).
I'm still trying to read about the whole AWS ecosystem and I need help with the ff:
For file storage, should I use S3 or EBS volumes mounted to an EC2 instance? From what I read, S3 is much cheaper and more scalable than EBS, but it's also slower. Is the speed difference really that huge or noticable for my use case? What are the advantages of a mounted EBS volume vs. S3?
What would be the best EC2 instance type for my use case? (i.e. frequent uploads and downloads) Will the General Purpose ones (T2, M4 etc) be enough to handle that load? (see above)
I can provide more info on my requirements/use cases if needed. Thanks!
Start with S3. S3 is a web api for putting and retrieving huge amounts of data, whereas EBS would be an NFS-mounted device. S3 will be more scalable from a data warehousing perspective, and in terms of access from multiple concurrent instances (should you do that, in the future.) Only use EBS if you actually need a filesystem for some reason. It doesn't sound like you do.
From there, you can look into some data archiving if you end up having huge amounts of data that doesn't need to be regularly available, to save some money.
Yes, use a t2 to start. Though, you should design your system so that it doesn't really matter, and you can easily teardown/replace instances. Using S3 helps with that pattern. You still need to figure out how you will deploy and configure your application to newly launched instances, though. You should /assume/ that your instance will go down, disappear, etc. So, you should be able to failover to another one on demand.

Cassandra on AWS

I'm new to AWS and also to Cassandra. I just read about EBS and S3 storage available in AWS. I was trying to figure out if we have Cassandra installed in EC2, which storage would it use? EBS or S3? Or is there other storage? I'm little confused with this. Please help me understand this.
Thanks
Aravind
You shouldn't run Cassandra on EBS, as recommended per Datastax itself :
"EBS volumes are not recommended for Cassandra data volumes for the following reasons:
EBS volumes contend directly for network throughput with standard packets. This means that EBS throughput is likely to fail if you saturate a network link.
EBS volumes have unreliable performance. I/O performance can be exceptionally slow, causing the system to back load reads and writes until the entire cluster becomes unresponsive.
Adding capacity by increasing the number of EBS volumes per host does not scale. You can easily surpass the ability of the system to keep effective buffer caches and concurrently serve requests for all of the data it is responsible for managing."
http://docs.datastax.com/en/cassandra/1.2/cassandra/architecture/architecturePlanningEC2_c.html
The answer above comes from Cassandra 1.2, a relatively old version. Documentation for newer versions of Cassandra indicate that EBS Optimized instances using GP2 SSD can be used for production workloads.
http://docs.datastax.com/en/cassandra/3.x/cassandra/planning/planPlanningEC2.html
Things that changed since then were the creation of EBS Optimized instances, which reduces and/or eliminates noisy neighbor throughput problems, and using GP2 SSD for EBS storage.
If you are just getting started, I would recommend EBS Optimized. The performance should be pretty good, but you gain a critical ability -> creating snapshots. This reduces the risk of your instance becoming unstable because you would have S3-backed volume snapshots for AWS to rebuild data from if a drive died.
This reduces the need to setup your Cassandra cluster across regions. One of the concerns that you have to build around when using Ephemeral is a whole region potentially going down, which could wipe out your entire cluster if you didn't build a multi-region cluster. With EBS, this isn't really a concern.
For Cassandra you need to use EBS. S3 is an object store with and API to store and retrieve objects, but not easy querying mechanisms. The use cases include backup and archiving, Disaster Recovery, Static Website Hosting, etc
However, you can use S3 for Cassandra backup.
You can also consider ephemeral disks (as Jeff mentions) and storage which comes with AWS instance.

What is difference between AWS EFS and S3?

AWS releases new Elastic File System this week. See http://aws.amazon.com/efs/
The page doesn't contain many details. I'd like to know its performance comparing to S3, as well as other differences.
You almost can't compare EFS and S3 because they are two very different things, even though there is some overlap in their functionality, or at least their apparent functionality.
They both store things and they both have a storage pricing model that scales linearly with usage over time.
But S3 is an object store with an HTTP interface and a mixed consistency model....
...while EFS is an actual filesystem with an NFS interface and as such will almost certainly offer immediate consistency.
S3, coupled with a utility like s3fs can be used in a way that mimics a filesysem, but not to the point of behaving in all ways like an actual filesystem.
One way of looking at EFS is that it is an answer to the question, "how do I attach an EBS volume to multiple instances at the same time?" Previously, of course, the answer was, "you can't." You can mount the filesystem exposed by EFS on any nunber of instances and the result should be very similar to what you'd see if you had a "shared volume."
Its performance compared to S3 is not really a fair comparison, again, because they are different things for different purposes, but EFS will almost without question be "faster" by any meaningful definition of the word.
Also, no software should be required in order to mount an EFS filesystem on a Linux system.
As already mentioned EFS is completely different to S3.
The simplest way to look at is to look at what the underlying technology is.
S3 is an object store, meaning it is a higher layer data storage system, essentially it is a database "blob" storage, storing data in an underlying simple database as an object.
It's designed for Write once Read many access, perfect for media data like image or video particularly as it is distributed and offers a very high level of redundancy.
EFS is a Network Storage system, underlying it is a storage array (SAN) and it offers the standard protocol for multi session network file systems (NFS)
It's built on high speed SSD drives and is intended for shared storage for your ec2 instances, think file servers.
It's been a long time coming for AWS and IMO this was one of the biggest missing key components for aws to really be a competitor to on-premise enterprise data centers.
Performance for EFS will be scalable and although I have not seen the details yet I am sure it will allow for provisioned IOPS just like EBS.
EFS is also considerably (10x) more expensive than S3 at $0.30 vs $0.03. From an IOPs perspective you should see better performance from EFS as it's SSD based and doesn't have the overheard of HTTP on top as does S3. It's essential NAS as a Service.
Two addition differences between the two:
AWS S3 offers Server-Side Encryption: http://docs.aws.amazon.com/AmazonS3/latest/dev/serv-side-encryption.html
The same is not currently offered in AWS EFS
Files stored in AWS S3 as public, are accessible via a public URL to anyone.
In AWS EFS however, in order to achieve the same, you'll need to deploy a web server that will serve your files.
Choosing between EFS and S3 is depend on your usage pattern
EFS availability and durability is same as S3
but both have different usage patterns
S3 have four common usage patterns:
static web content
host entire static websites
store data for large-scale analytics.
backup and archiving of critical data.
EFS is designed for applications thats concurrently access data from multiple EC2 instances.
simply, by having one EFS you can attach it to multiple EC2.. you can't do that with EBS.
Amazon claim that S3 performance is more than any current users needs.
EFS performance has two modes
General Purpose
Max I/O
General Purpose is the default and it's appropriate for most operations type.
but, if your workload will exceed 7000 file operations per second then Max I/O is your target