Here is an example for me trying to understand the under the hood mechanism.
I decide to upload a 2GB file onto my S3 bucket, and I decide to use the size of 128MB for the parts. Then I will have
(2 * 1024) / 128 => 16 parts
Here are my questions:
Am I going to see 16 128MB objects in my bucket or a single 2GB
object in my bucket?
How can S3 understand the order of the parts (1->2->...->16) and
reassemble them into a single 2GB file when I download them back? Is
there an extra 'meta' object (see the above question) that I need to download first to help the client to achieve this reassembling-needed information?
When the s3 client download the above in parallel, at what time does it write the file descriptor for this 2GB file in the local file system (I guess it does not know all the needed information before all the parts have been downloaded)?
While uploading the individual parts, there will be multiple uploads stored in Amazon S3 that you can view with the ListMultipartUploads command.
When completing a multipart upload with the CompleteMultipartUpload command, you must specify a list of the individual parts uploaded in the correct order. The uploads will then be combined into a single object.
Downloading depends upon the client/code you use -- you could download an object in parallel or just single-threaded.
Related
I stuck with the following problem: I need to upload objects in small parts (512KB), so I can not use multipart upload (since the minimum 5MB restriction). On the grounds of that, I have to put my parts in a "partitions" bucket and run a Cron task to download partitions and upload a single concatenated object into a "completed" bucket.
I would like to clarify, however, that there is no more elegant way to do this except direct download and concatenation. AWS CLI suggests one can copy objects as a whole, but I see no way to copy and concatenate several objects into one. Is there a way to do this via AWS S3 means?
UPD: I am not guaranteed 512KB chunk size (in fact, it is 512KB to 16MB), but it is usually 512KB and this limit takes origin from vendor of my IP cameras so I can not really change that. And I know the result size beforehead, the camera tells me "I am going to upload 33MB" with a separate call to my backend, but I have no control over number of chunks or their size except the guaranteed boundaries above.
I'm trying to sync a large number of files from one bucket to another, some of the files are up to 2GB in size after using the aws cli's s3 sync command like so
aws s3 sync s3://bucket/folder/folder s3://destination-bucket/folder/folder
and verifying the files that had been transferred it became clear that the large files had lost the metadata that was present on the original file in the original bucket.
This is a "known" issue with larger files where s3 switches to multipart upload to handled the transfer.
This multipart handeling can be configured via the .aws/config file which has been done like so
[default]
s3 =
multipart_threshold = 4500MB
However when again testing the transfer the metadata on the larger files is still not present, it is present on any of the smaller files so it's clear that I'm heating the multipart upload issue.
Given this is an s3 to s3 transfer is the local s3 configuration taken into consideration at all?
As an alternative to this is there a way to just sync the metadata now that all the files have been transferred?
Have also tried doing aws s3 cp with no luck either.
You could use Cross/Same-Region Replication to copy the objects to another Amazon S3 bucket.
However, only newly added objects will copy between the buckets. You can, however, trigger the copy by copying the objects onto themselves. I'd recommend you test this on a separate bucket first, to make sure you don't accidentally lose any of the metadata.
The method suggested seems rather complex: Trigger cross-region replication of pre-existing objects using Amazon S3 inventory, Amazon EMR, and Amazon Athena | AWS Big Data Blog
The final option would be to write your own code to copy the objects, and copy the metadata at the same time.
Or, you could write a script that compares the two buckets to see which objects did not get their correct metadata, and have it just update the metadata on the target object. This actually involves copying the object to itself, while specifying the metadata. This is probably easier than copying ALL objects yourself, since it only needs to 'fix' the ones that didn't get their metadata.
Finally managed to implement a solution for this and took the oportunity to play around with the Serverless framework and Step Functions.
The general flow I went with was:
Step Function triggered using a Cloudwatch Event Rule targetting S3 Events of the type 'CompleteMultipartUpload', as the metadata is only ever missing on S3 objects that had to be transfered using a multipart process
The initial Task on the Step Function checks if all the required MetaData is present on the object that raised the event.
If it is present then the Step Function is finished
If it is not present then the second lambda task is fired which copies all metadata from the source object to the destination object.
This could be achieved without Step Functions however was a good simple exercise to give them a go. The first 'Check Meta' task is actually redundant as the metadata is never present if multipart transfer is used, I was originally also triggering off of PutObject and CopyObject as well which is why I had the Check Meta task.
My requirement to upload large file (35gb), when the upload is in progress need to start the download process on the same file. Any storage service which allows develop .net application
Because Amazon s3 will not allow simultaneously upload and download on
You could use Microsoft Azure Storage Page or Append Blobs to solve this:
1) Begin uploading the large data
2) Concurrently download small ranges of data (no greater than 4MB so the client library can read it in one chunk) that have already been written to.
Page Blobs need to be 512 byte aligned and can be read and written to in a random access pattern, whereas AppendBlobs need to be written to sequentially in an append-only pattern.
As long as you're reading sections that have already been written to you should have no problems. Check out the Blob Getting Started Doc: https://azure.microsoft.com/en-us/documentation/articles/storage-dotnet-how-to-use-blobs/ and some info about Blob Types: https://msdn.microsoft.com/library/azure/ee691964.aspx
And feel free to contact us with any follow up questions.
Actually title was a question :)
Do AWS S3 support file streaming in case if file is not 100% uploaded? Client #1 split files into small chunks and start uploading them using Multipart Upload. Client #2 start downloading them from S3. So, as result client #2 don't need to wait until client #1 has uploaded the whole file.
Is it possible to do it without additional streaming server?
This is not natively supported by S3.
S3 allows the individual parts of a multipart upload to be uploaded sequentially, or in parallel, or even out of their logical order, over an essentially unlimited period of time.
It is not until you send the CompleteMultipartUpload request that the parts are verified by S3 as all being present, and having the correct checksums, that the final object is assembled from the parts, and is created in the bucket (or overwrites the former object with the same key, if there was one) if the parts are all present and their integrity is intact. Until then, the object -- as an object at the designated key -- does not technically exist, so it can't be downloaded.
What is the size of data that can be sent using the GET PUT methods to store and retrieve data from amazon s3 cloud and I would also like to know where I can learn more about the APIs available for storage in Amazon S3 other than the documentation that is already provided.
The PUT method is addressed in the respective Amazon S3 FAQ How much data can I store?:
The total volume of data and number of objects you can store are
unlimited. Individual Amazon S3 objects can range in size from 1 byte
to 5 terabytes. The largest object that can be uploaded in a single
PUT is 5 gigabytes. For objects larger than 100 megabytes, customers
should consider using the Multipart Upload capability. [emphasis mine]
As mentioned, Uploading Objects Using Multipart Upload API is recommended for objects larger than 100MB already, and required for objects larger than 5GB.
The GET method is essentially unlimited. Please note that S3 supports the BitTorrent protocol out of the box, which (depending on your use case) might ease working with large files considerably, see Using BitTorrent with Amazon S3:
Amazon S3 supports the BitTorrent protocol so that developers can save
costs when distributing content at high scale. [...]