Cloud Files - FAQs

Getting Started

How can I get live support for Cloud Files?

Support is available by email at Monday through Friday, 9AM to 5PM CST. Tech support will be happy to answer any questions you have about Cloud Files, except for code related issues. If you do have questions about design or coding please try our forums or documentation.

How Can I Use Akamai’s CDN With Cloud Files?

Rackspace Cloud Files uses Akamai Technologies, Inc. a leading, tier one, global Content Delivery Network (CDN) provider to offer the benefits to all Cloud Files users. Today Akamai handles tens of billions of daily Web interactions for their customers such as Audi, NBC, Fujitsu, U.S. Department of Defense, and NASDAQ.

The Rackspace CloudFiles/Akamai relationship brings full-fledged, robust CDN capabilities and unlimited file storage to developers and corporate IT departments alike. The CDN capability will greatly enhance the quality of the end user experience by speeding the delivery of bandwidth-heavy rich content, including audio and video. For literally pennies per gigabyte of bandwidth and storage and no upfront commitments, the CDN advantage is now available to all not just to the giants of the internet. This partnership brings unlimited online storage, scalable content delivery, and application acceleration services, thereby allowing businesses to more easily and affordably distribute content to millions of end users around the world. Together with Akamai, Rackspace has democratized content delivery.

With Akamai’s service, Cloud Files brings a powerful and easy way to publish content over a world-class, industry leading CDN. A Cloud Files user automatically gets access to this network. Users have to mark containers for publishing to CDN, and then they are instantly accessible through Akamai CDN. The propagation of content to the edge locations is done automatically behind the scenes. The Rackspace Cloud/Akamai offering is not a one-off solution; content published through it is distributed across their entire infrastructure just as it is for other customers.

In the Rackspace Cloud control panel, it is a matter of creating a Container (the storage compartment for data), uploading Objects (the files to serve over CDN), and marking the Container as “public”. The Container is then assigned a unique URL which can be combined with Object names to embed in web pages, email messages, blog posts, etc. For example, a user could upload a photo to a Container called “images”. When this Container is published, it will be assigned a unique URL like The user could then share a link to the photo with link like When that link is accessed, the photo is served from the CDN; it’s that simple!

What is a Container in Cloud Files?

A Container is a “storage compartment” for your data and provides a way for you to organize that data. You can think of a Container as analogous to a folder in Windows® or a directory in UNIX®. The primary difference between a Container and these other “file system” constructs is that Containers cannot be nested. You can have up to 500,000 Containers in your account, but they only exist at the “top level” of your account and Containers cannot reside within other Containers.

Note: Containers scale to about one million objects before peformance degrades. Containers can only be removed from Cloud Files if they do NOT contain any storage Objects. In other words, make sure the Container is empty before attempting to delete it.

What are the naming requirements for Cloud Files objects and containers?

The naming requirements for Cloud Files objects and containers (such as illegal characters and name length limits) include:

  • Container names may not exceed 256 bytes and cannot contain a slash (/) character.
  • Object names may not exceed 1024 bytes, but they have no character restrictions.
  • Object and container names must be URL-encoded and UTF-8 encoded.

How do I access Cloud Files?

First you must make sure you have generated a valid API Access Key. Then you can use either the Cloud Files user interface in the Rackspace Cloud Control Panel or one of our programming interfaces.

See Cloud Files and CDN for more details.

Where can I find Cloud Files documentation?

Account Services

Can Cloud Files be used for my Cross-domain policy file?

No. The Cloud Files CDN does not support exposing a custom crossdomain.xml file, as this is a required file by the Openstack Swift project. OpenStack Swift uses this as a global configuration file for the installation, and can not be modified for multiple tenants, such as our Public Cloud.

Is there a Cloud Files specific SLA?

Please click here to view The Rackspace Cloud Terms of Service.


Why does uploading a file in the Control Panel set the Allow-Origin header on my container?

When you upload a file in the Cloud Control Panel, an Allow-Origin header is set on the container to support cross-origin resource sharing (CORS). Browsers prevent AJAX requests between different domains by default. Because the Cloud Files API and the Control Panel reside on different domains, CORS must be enabled to support uploads directly to a container. When the upload succeeds, the CORS headers are removed.

By allowing the browser to upload directly to the Cloud Files API, maximum upload performance can be achieved.

Read more about CORS at .

Cloud Files - How do Permissions Work?

There are no permissions or access controls around containers or objects other than being split into separate accounts. Users must authenticate with a valid user name and API Access Key, but once authenticated, they can create or delete containers and objects only within that account.

At this time, there is no way to publicly access the objects stored in Cloud Files unless that container is published to CDN. Each request to Cloud Files must include a valid “storage token” in an HTTP header transmitted over a HTTPS connection.

Web Technologies

Getting Started with Cloud Files Streaming

Streaming content through Cloud Files lets you deliver video content quickly and easily, without making your users download the content first. They can begin viewing your content immediately and can jump around the video stream without needing to buffer.

Because Rackspace uses HTTP delivery for streaming content, you can use the Akamai CDN network to deliver your content. This means the performance should be identical to CDN speeds customers are used to. Before you begin, you must CDN-enable the container that holds your streaming content. In the Cloud Control Panel, click the gear icon of the container and select “Make Public (Enable CDN)”.

Once your container is CDN-enabled, you will need its Streaming URLs. In the Cloud Control Panel, click the gear icon for the container and select “View All Links…”. Below is an example of the CDN links that display:

iOS Streaming:

There are several different ways to stream your content with Cloud Files. Click a link below to find out more for each approach.

Cloud Files Streaming

Why have we chosen to support specific players?

Many Rackspace customers are not flash developers, but still want to use a streaming offer. There are a few players that are dominating the market, and we will plan to support each of them. Custom plugins are required in order for Streaming delivery to work properly over the Akamai network. As Akamai adds support for more players, our customers will have access to them.

Why are we not using RTMP?

  • RTMP is probably the most popular delivery format today, but the market is quickly moving towards HTTP delivery for Streaming content. Here are just a few reasons the market is moving towards HTTP.
  • Accessibility- Many firewalls block RTMP and RTSP streaming protocols because corporations don’t want users watching video at work. HTTP appears to be normal web traffic, meaning that videos served over HTTP are usually left open.
  • Startup times- Akamai sees a significant reduction in stream startup times on average for traffic served via HTTP.
  • Throughput (image quality)- With the HTTP network being larger than many other networks, Akamai is closer to the end user on their HTTP network meaning they get better throughput of data. that means customers will experience higher bit rates uninterupted (and without buffering) and increase the end user’s over all experience.

Is this available internationally?

Yes, this is available to both US and UK Cloud customers.

Content Delivery Network

Does CDN management in Cloud Files support exposing a custom crossdomain.xml file?

Cloud Files CDN does not support exposing a custom crossdomain.xml file because this file is required by the Openstack Swift project, on which Cloud Files is based.

OpenStack Swift uses the crossdomain.xml file as a global configuration file for installation. The file cannot be modified for multiple tenants, such as our Rackspace Public Cloud.

For more information, see Cross-domain Policy File.

If your site requires a custom crossdomain.xml file, we suggest you take a look at Rackspace CDN. Rackspace CDN allows you to customize your configuration and define your own origin web server.

What is the TTL attribute in a Cloud Files container?

This article describes the use of the Time To Live (TTL) attribute and how it works.

When you create a container in Cloud Files and you make that container public, the files within that container have a designated TTL. The TTL is the time interval after which the CDN will reread the contents of the container. This attribute and its value can be modified in the CDN through the Cloud Files user interface.

New values take effect after the current TTL cycle is completed. The TTL can be any value between 15 minutes and 50 years. Use higher numbers for static content that doesn’t change often, and use smaller numbers for content that changes more often. If you require a longer TTL, see the following blog post about using the API to set TTL: Extending TTL for Cloud Files CDN Users.

Use the following steps to modify a container’s TTL within the Cloud Control Panel:

  1. Log in to the Cloud Control Panel.
  2. In the top navigation bar, select Storage > Files.
  3. If the container is not already public, click the gear icon next to the container and select Make Public (Enable CDN). In the popup box, click Publish to CDN.
  4. Click the gear icon next to the container again and select Modify Time To Live (TTL).
  5. Enter the TTL for the container in seconds, and then click Save TTL.

How Do I Use the Cloud Files CDN Manager?

This article describes how to create a container within Cloud Files and manage files in it through the Cloud Files interface.

What is the CDN?

Using the Akamai content delivery network (CDN) service, Cloud Files brings you a powerful and easy way to publish content over a world-class industry leading CDN. Customers automatically get access to this network as part of using the Cloud Files service. The way it works is by distributing the content that you upload to Cloud Files across a global network of edge servers. What this means is that when someone is viewing content from your site, your CDN-enabled content will be served to them from the closest geographic edge server to their location. This feature dramatically increases the speed at which websites can load, no matter where your viewer is located.

This can be a great advantage when hosting content for an international audience. Though you can also use the API to upload content to Cloud Files, another way is to use the File Manager interface in the Cloud Control Panel. To store content on Cloud Files, you start by creating a container for your content. The container name should have no breaks, spaces, or special characters. Unlike a folder or directory, a container cannot have subdirectories. All your content will be at one level below the container name.

Create a container

  1. Log in to the Cloud Control Panel.
  2. In the top navigation bar, select Storage > Files.
  3. Click Create Container.
  4. Name the container, and then click Create Container.
  5. Click the gear icon next to the container to be made public and select Make Public (Enable CDN).
  6. Click Publish to CDN.

You can now share the files within the container.

Upload files to the container

  1. Click on the name of the container to which you want to upload files.
  2. Click Upload Files and select the files to upload.
  3. Click Open.
  4. After the file is uploaded, click Close Window.

The file appears the list of available files within the container.

  1. Click the gear icon next to your file and select View All Links.

Options for sharing your file are displayed.

To learn more about how to operate with Cloud Files through the API, read the article Connecting to Cloud Files and read the API Developer Guides.


Who is Akamai?

Akamai Technologies, Inc. is publicly traded: (NASDAQ: AKAM) company founded in 1998. Akamai has a pervasive, highly-distributed cloud optimization platform with over 73,000 servers in 70 countries within nearly 1,000 networks.

What will I experience when Akamai is implemented as my new CDN provider?

Rackspace expects no customer impact during your transition to Akamai. Once we flip the switch to have a customer’s content served by Akamai, Akamai will begin supporting both new URLs and all other existing CDN provider URLs.

This means that CDN customers who currently have Limelight URLs coded into their websites will continue to serve content using those URLs when they are transitioned to Akamai, but they will be distributed over the Akamai network. At this time, we do not have any plans to discontinue the legacy URLs.

If a customer requests their URL (either in the Control Panel or via API) for an object, they will be presented with a new Akamai URL. This does not mean that old URLs are invalid. However, as Rackspace releases new features like CNAME and SSL, customers will need to reference their new Akamai URL instead of their legacy URL.

Will customers have to change their code to use Akamai?


Will customers have to do anything different in the control panel?

No, as we add new features, we will educate our customers.

Should customers anticipate any downtime during this implementation?

No downtime is expected during the implementation of the Akamai platform.

Will the Cloud Files API be different?

No, all customers facing API calls will remain the same.

What are the benefits Of using a CDN?

  • Higher capacity and scale- Strategically placed servers increase the network backbone capacity and number of concurrent users handled. For instance, when there is a 10 Mbit/s network backbone and 100 Mbit/s central server capacity, only 10 Mbit/s can be delivered. But when 10 servers are moved to 10 edge locations, total capacity can be 10*10 Mbit/s.
  • Lower delivery costs - Strategically placed edge servers decrease the load on interconnects, public peers, private peers and backbones, freeing up capacity and lowering delivery costs. A CDN offloads traffic on a backbone network by redirecting traffic to edge servers.
  • Lower network latency and packet loss - End users experience less jitter and improved stream quality. CDN users can therefore deliver high definition content with high Quality of Service, low costs and low network load.
  • Higher Availability - CDNs dynamically distribute assets to strategically placed core, fallback and edge servers. CDNs may have automatic server availability sensing with instant user redirection. CDNs can thus offer 100% availability, even with large power, network or hardware outages.
  • Better Usage analytics – CDNs can give more control of asset delivery and network load. They can optimize capacity per customer, provide views of real-time load and statistics, reveal which assets are popular, show active regions and report exact viewing details to customers.

What is a CDN?

A content delivery network (CDN) is a network of computers that delivers content to users across the globe. By leveraging a network, the content provider can deliver information quicker to end users across the globe, while improving performance, and increasing scalability and efficiency. The place where the content is originally stored is the origin server, and endpoint servers where users across the globe access the content are called edge servers. The longer it takes for information to travel from an edge server to the user, the slower the load time of the content.

The speed of delivery is constrained by the slowest network in the chain of computers that deliver the content from origin to end user. CDNs place servers around the world and, depending on where the end user is located, serves them with the closest or most appropriate server. CDNs cut down on the amount of travel your content must make. This is shown in the following figures.


CDNs focus on improving performance of web page delivery. CDNs like Akamai’s support progressive downloads, which optimizes delivery of digital assets such as web page images. CDN nodes and servers are deployed in multiple locations around the globe over multiple internet backbones. These nodes cooperate with each other to satisfy data requests by end users, transparently moving content to optimize the delivery process. The larger the size and scale of their Edge Network deployments, the better the CDN.

They generally push the Edge Network closer to end users. The Edge Network is grown outward from the origins by purchasing co-location facilities, bandwidth, and servers. CDNs choose the best location for serving content while optimizing for performance. They may choose locations that are the fewest hops or fewest number of network seconds away from the requesting client. CDNs choose the least expensive locations while optimizing for cost. CDNs use various techniques such as web caching, server-load balancing, and request routing to achieve the optimization goals.

Because closer is better, web caches store popular content closer to the user. These shared network appliances reduce bandwidth requirements, reduce server load, and improve the client response times for content stored in the cache.

Server-load balancing uses a web switch, content switch, or multilayer switch to share traffic among a number of servers or web caches. Here, the switch is assigned a single virtual IP address. Traffic arriving at the switch is then directed to one of the real web servers attached to the switch. This has the advantages of balancing load, increasing total capacity, improving scalability, and providing increased reliability by redistributing the load of a failed web server and providing server health checks.

Request routing directs client requests to the content source best able to serve the request. This may involve directing a client request to the service node that is closest to the client, or to the one with the most capacity. A variety of algorithms for Global Server Load Balancing (shown in diagram) are used to route the request. Choosing the closest service node is done using a variety of techniques including proactive probing and connection monitoring.

File Transfers and File Sharing

Does Cloud Files support the transfer of large files?

Yes, the Rackspace Cloud now supports the transfer and storage of larger files. Following is a list of frequently asked questions about our large file support.

How does Rackspace support the upload of large files to Cloud Files?

Although support for uploading content to Cloud Files through the Cloud Control Panel is limited to files smaller than 5 GB, we can accommodate the transfer of files larger than 5 GB by allowing you to segment your files into multiple file segments.

How large should my file segments be?

Rackspace does not enforce any lower limits on the file size. File segments cannot be larger than 5 GB, and we recommend not storing file segments that are smaller than 100 MB.

Can I serve my large files over the CDN?

At this time, you cannot serve files larger than 10 GB from the CDN.

Is there a simpler way to use this process?

We have created a tool called Swift to make this process easier. Swift segments your large file for you, creates a manifest file, and uploads the segments accordingly. After it uploads the segments, Swift manages the segments for you, deleting and updating them as needed. You can get information about the Swift Tool and download the Swift tool.

When should I use the API instead of the Swift tool?

If you are interested in developing against the Rackspace Large File Support code to incorporate into your application, you should work directly with the Cloud Files API. Use the following steps:

  1. Upload the segments:

    curl -X PUT -H 'X-Auth-Token: <token>' \\
    http://<storage\_url>/container/myobject/1 --data-binary '1'
    curl -X PUT -H 'X-Auth-Token: <token>' \\
    http://<storage\_url>/container/myobject/2 --data-binary '2'
    curl -X PUT -H 'X-Auth-Token: <token>' \\
    http://<storage\_url>/container/myobject/3 --data-binary '3'
  2. Create the manifest file:

    curl -X PUT -H 'X-Auth-Token: <token>' \\
    -H 'X-Object-Manifest: container/myobject/' \\
    http://<storage\_url>/container/myobject --data-binary ''
  3. Download the segments as a single object:

    curl -H 'X-Auth-Token: <token>' \\

When should I use the Swift tool instead of the API, and what is the process?

If you want to upload large files but do not want to incorporate our code into an application, you might find it easier to use the Swift tool for your uploads and management. If you are using the tool, the process looks as follows:

The following code uploads large_file to test_container in 10 MB segments and then creates the manifest file so the segments can be downloaded as one.

swift upload test_container -S 10485760 large_file

You can change the size of the segments are by changing the value following the -S option.

The following code downloads the large file as a single object:

swift download test_container large_file

In the above example, Swift will upload all the segments into a second container named test_container_segments. These segments will have names using the format of <name>/<timestamp>/<size>/<segment>. For example:


The main benefit for using a separate container is so the main container will not be polluted with all the segment names. The naming format is so that an upload of a new file with the same name won’t overwrite the contents of the first until the last moment when the manifest file is updated.

For more information on using the swift tool, see the OpenStack Swift documentation.

What will the download experience be like?

After files are segmented and uploaded with a manifest file, your large file will be served as a single file, so the experience will mimic the download or service of any other object retrieval.

Do I have access to my file segments?

Yes, you can edit your file segments just like any other object within Cloud Files.

How do I ensure that my files are linked correctly?

Include your manifest file in your upload. You can change your file name by editing this manifest file as well. We recommend using prefixing in your file segments to easily map your manifest file to the portions of your large file. For example, you could name your segments as follows:


In this case, you would point your manifest file to the prefix: Myfavoritemovie .

Can I use this feature from the Cloud Control Panel?

At this time, Rackspace has not implemented this functionality into the Rackspace Cloud Control Panel.

Application Development

Where can I find Cloud File Developer Guides?

Developer guides are available on the Rackspace API documentation site. Documentation is available for the raw API and for language-specific SDKs.

Why does one of my Cloud Files scheduled tasks get terminated abruptly?

The Rackspace Cloud system restricts the maximum execution time of any one cron job to 15 minutes. Please make sure that your script is well tested and can complete its intended job within this time frame.


Where can I see the API?

The API documentation is available from the Rackspace API documentation site.