Difference between Object Storage And File Storage

http://stackoverflow.com/questions/14925791/difference-between-object-storage-and-file-storage

The simple answer is that object accessed storage systems or services utilize APIs and other object access methods for storing, retrieving and looking up data as opposed to traditional file or NAS. For example with file or NAS, you access storage using NFS (Network File System) or CIFS (e.g. windows file share) aka SMB aka SAMBA where the file has a name/handle with associated meta data determined by the file system.

The meta data includes info about create, access, modified and other dates, permissions, security, application or file type, or other attributes. Files are limited by the file system in terms of their size, as well as the number of files per file system. Likewise, file systems are limited by their total or aggregate size in terms of space capacity and the number of files in the filesystem.

Object access is different in that while file or NAS front-end or gateways or plugins are available for many solutions or services, primary access is via an API where an object can be of arbitrary size (up to the maximum of the object system) along with variable sized meta data (depends on the object system/service implementation). With most object storage systems/services you can specify anywhere from a few Kbytes of user defined meta data or GBytes. What would you use GBytes of meta data for? How about in addition to normal info, adding more data for policies, managements, where other copies are located, thumbnails or small previews of videos, audio, etc.

Some examples of object access APIs or interfaces include Amazon Web Services (AWS) simple storage services (S3) or other HTTP and REST based ones, SNIA CDMI. Different solutions will also support IOS (e.g. iphone/ipad) access, SOAP, Torrent, WebDav, JSON, XAM among others plus NFS/CIFS. In addition many of the object storage systems or services support programmatic bindings for python among others. The APIs allow you to essentially open a stream and then get or put, list and other functions supported by the API/system to determine how you will use it.

For example, I use both Rackspace Cloud files and Amazon S3 (in addition to EBS and Glacier) for backing up, storing, and archiving data. I can access the objects stored via a web browser or tools including Jungle disk (JD) which is what I backup and synchronize files with. JD handles the object management and moves data to both Rackspace as well as Amazon for me. If I were inclined, I could also do some programming using the APIs and then directly access either of those sites supplying my security credentials to do things with my stored objects.

Here is a link to object and cloud storage primer from a session I did in Holland last year that has some simple examples of objects and access. http://storageio.com/DownloadItems/Nijkerk_Nov2012/SIO_IndustryTrends_CloudObjectStorage.pdf

Using the programmatic binding, you would define your data structures or objects in your program and then use the APIs or calls for storing, retrieving, listing of data, meta data access etc. If there is a particular object storage system, software or service that you are looking to work with or need to know how to program to, go to their site and you should find their SDK or API info with examples. With objects, once you create your initial bucket or container on a service or with a product/system, you then simply create and store additional objects as you go.

Here is a link as an example to AWS S3 API/programming: http://docs.aws.amazon.com/AmazonS3/latest/API/IntroductionAPI.html

In theory object storage systems are talked about has having unlimited numbers of objects, or object size, in reality, most systems, solutions, software or services are limited by what they have either tested or currently support, which can be billions of objects, with objects sizes of 5GByte or larger. Pay attention to the limits on specific services or products as to what is actually tested, supported vs. what is architecturally possible or what is implemented on webex or powerpoint.

Again its very service and product/service/software dependent as to the number of objects, size of the objects, size of meta data, and amount of data that can be moved in/out via their APIs. However, it is generally safe to assume that object storage can be much more scalable (depending on implementation) than file systems (without using global name space, federation, file virtualization or other techniques).

Also in my book Cloud and Virtual Data Storage Networking (CRC Press) that is Intel Recommended Reading, you will find more information about cloud and object storage.

 

There are some very fundamental differences between File Storage and Object Storage.

File storage presents itself as a file system hierarchy with directories, sub-directories and files. It is great and works beautifully when the number of files is not very large. It also works well when you know exactly where your files are stored.

Object storage, on the other hand, typically presents itself via. a RESTful API. There is no concept of a file system. Instead, an application would save a object (files + additional metadata) to the object store via. the PUT API and the object storage would save the object somewhere in the system. The object storage platform would give the application a unique key (analogous to a valet ticket) for that object which the application would store in the application database. If an application wanted to fetch that object, all they would need to do is give the key as part of the GET API and the object would be fetched by the object storage.

Hope this is now clear.