File level and block level storage

A quick answer is that you don't technically need both. Block level storage is 'disk', file level storage is a layer above disk that can be presented by an appliance integrated with disk storage.

I admin PBs  of block level SAN arrays. All file level services here are provided by  servers (generally virtual ) that I provision block storage to.  We don't use unified or file level devices, but instead build our own. That is an institutional preference based on our needs and available labor. 

Why do we need trucks and buses ?

Both have an engine and wheels and could transport both cargo and people.

Because there are different storage requirements and use cases

File storage for example allows for sharing the same data to multiple hosts and allows IP distance.

I would suggest to start with some storage 101 trainings – EMC also has some techbooks available for download

Yep – but then at some level you are also using file level storage (NFS or CIFS) – you just use generic Windows or Unix servers instead purpose-built NAS storage systems to do so

I'd absolutely agree with that...

People don't care about disk, they care about files.  Disk is just an infrastructure layer that facilitates files.

But you don't need a NAS storage system to provide infrastructure, and even a purpose built NAS, is still just an abstraction of the disk infrastructure that it is built on.

I didn't really have a horse in the race, but I believe that the place where we put NAS appliances off to the side was around when we adopted AD infrastructure.  The question:  "Does this NAS support AD, and everything that we may want to do with it?" always yielded vague, limited, or unsatisfactory answers.  While 'purpose built', a NAS appliance is purpose built to be *generally* useful.  It doesn't necessarily provide the same flexibility that a purpose built, 'thick' if you will, file server does.

AD functions use AD file servers, other workloads use Linux based NFS boxes, etc., and in all cases the functionality and scalability is designed locally, from a broad range of options, without a vendor lock-in.

I recall a project that was trying to use a NS-120 for a data-warehousing and query application.  It all looked fine until they discovered...post sales/pre-implementation, that it could only handle a finite and relatively small (32TBs or something...) cap on what it could serve.  The CX4-120 behind it was only limited by the available disk...and in fact, a second array was added beside it with the resulting physical file server using resources from both relatively seamlessly.  So the data movers sat idle, while the block array, combined with a pair of physical servers, did the job.

I just want to ask at what situation we need object, block and file.

Everything is written in hard drives. so why object, file and block is stored?

Dear how you will define that customer is using object, file or block data?

in all of these, storage is connected to server through network.

Dear how you will define that customer is using object, file or block data?

in all of these, storage is connected to server through network.

Whether object, block or file access is used is typically determined by your application

which applications provide block, which provide object and file. please define these.

ROTFLOL