Cloud Files - FAQs

Getting started

How can I get live support for Cloud Files?

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

What is a container in Cloud Files?

A container is a *storage compartment* for your data and enables 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 you can't nest containers. You can have up to 500,000 Containers in your account. However, they only exist at the top level of your account, and containers cannot reside within other containers.

Containers scale to about one million objects before performance degrades. You can remove containers from Cloud Files only 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.

What does *eventual consistency* mean in Cloud Files?

A key characteristic of Cloud Files is *eventual consistency*. In computing, the CAP (Consistency, Availability, and Partition Tolerance) theorem states that distributed systems cannot achieve consistency, availability, *and* network failure tolerance—they can achieve only two. For example, a system can be consistent (that is, all reads get the most current data) and handle network failures, but they must sacrifice availability to do so. Or, a system can choose to handle network failures and have perfect availability, but they must sacrifice consistency to do so. Distributed systems must always handle network failures, so they must choose to sacrifice either availability or consistency.

Storage systems become distributed as they grow. OpenStack Swift (the basis for the Rackspace Cloud Files service) sacrifices consistency for availability and network failure tolerance. This choice enables the system to scale to enormous levels and provide massive uptime, but it also means that in certain scenarios, some data might not update throughout the entire system. For example, a container listing might not update after the system writes an object. OpenStack Swift queues the container listing update and allows the object write to succeed. This sort of consistency model is called *eventual consistency*.

Where can I find Cloud Files documentation?

Find Cloud Files documentation in the following locations:

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 because the OpenStack Swift project considers this a required file. OpenStack Swift uses this as a global configuration file for the installation, and you can't modify it for multiple tenants, such as our Public Cloud.

Is there a Cloud Files specific SLA?

Yes, you can view the Rackspace Cloud Terms of Service.


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

When you upload a file in the Cloud Control Panel, an `Allow-Origin` header supports cross-origin resource sharing (CORS) on the container. Browsers prevent Asynchronous JavaScript and XML (AJAX) requests between different domains by default. Because the Cloud Files API and the Cloud Control Panel reside on different domains, CORS must support uploads directly to a container. When the upload succeeds, the system removes the CORS headers.

By allowing the browser to upload directly to the Cloud Files API, you can achieve maximum upload performance.

Read more about CORS.

How do permissions work?

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

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

Cloud Files streaming

Note: X-Cdn-Streaming-Uri and X-Cdn-Ios-Uri links will be discontinued on July 31, 2022

Why have we chosen to support specific players?

Rackspace customers are not generally flash developers but still want to use a streaming offer. Some vendors dominate the market, and we plan to support each of them. Streaming delivery requires custom plugins to work properly over the Akamai® network. As Akamai adds support for more players, our customers gain access to them.

Why are we not using RTMP?

Real-Time Messaging Protocol (RTMP) is probably the most popular delivery format today, but the market is moving towards HTTP delivery for Streaming content. Following are just a few reasons the market is moving towards HTTP:

  • Accessibility: Firewalls block RTMP and RTSP streaming protocols because corporations don't want users watching videos at work. HTTP appears to be normal web traffic, so firewalls usually leave videos served over HTTP open.
  • Startup times: Akamai sees a significant reduction in stream startup times on average for traffic served over 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, which means they get better data throughput. That means customers experience higher bit rates uninterrupted (and without buffering) and increase the end-user's overall experience.
Is this available internationally?

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

Content Delivery Network (CDN)

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 the OpenStack Swift project, on which we based Cloud Files, requires this file.

OpenStack Swift uses the **crossdomain.xml** file as a global configuration file for installation. You cannot modify the file 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?

When you create a container in Cloud Files and make that container public, the files within that container have a designated time to live (TTL). The TTL is the time interval after which the CDN rereads the contents of the container. For more information on managing the TTL attribute,see Manage Time to Live (TTL) in a Cloud Files Container.

What is the CDN?

By 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. For more information on using CDN with Cloud Files, see Getting Started with Cloud Files and CDN.

What is Akamai?

Akamai Technologies, Inc. is a publicly-traded company founded in 1998 (NASDAQ: AKAM). 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 my new CDN provider?

Rackspace expects no customer impact during your transition to Akamai. After we flip the switch to have Akamai serve a customer's content, Akamai supports new URLs and all other existing CDN-provider URLs.

This means that CDN customers who currently have Limelight URLs coded into their websites continue to serve content by using those URLs when they transition to Akamai, but we distribute them 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 Cloud Control Panel or through API) for an object, we present them 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 should reference their new Akamai URL instead of their legacy URL.

Do customers have to change their code to use Akamai?


Do customers have to do anything different in the Cloud Control Panel?

No, as we add new features, we update our customers.

Should customers anticipate any downtime during this implementation?

No, you should expect no downtime during the implementation of the Akamai platform.

Is the Cloud Files API different?

No, all customers facing API calls remain the same.

What are the benefits Of using a CDN? - **Higher capacity and scale**: Strategically placed servers increase the network backbone capacity and the number of concurrent users handled. For instance, when there is a 10 Megabits per second (Mb/s) network backbone and 100 Mb/s of central server capacity, the CDN can deliver only 10 Mb/s. But when we move ten servers to ten edge locations, the total capacity grows to 10x10 or 1000 Mb/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 deliver high-definition content with high service quality, low costs, and low network load. - **Higher Availability**: CDNs dynamically distribute assets to strategically placed core, fallback, and edge servers. CDNs might 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.

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 support of large files.

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 for 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 it.

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

If you want to develop against the Rackspace Large File Support code to incorporate into your application, you should work directly with the Cloud Files API. For more information, see Use the API to manage large files.

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.

For more information, see Use Swift to manage large files.

What is the download experience like?

After files are segmented and uploaded with a manifest file, we serve your large file as a single file, so the experience mimics the download or service of any other object retrieval.

Do I have access to my file segments?

Yes, you can edit your file segments 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 map your manifest file to the portions of your large file.

For example, you could name your segments as follows:

    and so on

In this case, you 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.

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

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

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