Hi Chetan,
Thank you for writing to NetApp Community.
1] How can I check stripe size?
NetApp stripe size is 4KB irrespective of number of disks or applicartion you are using....
Refer to this TR, Although this is a old one but it has good explanation http://www.netapp.com/us/media/tr-3001.pdf
2] How can see where is my getting stored?
Actually you cannot have visibility of actual data from the NetApp but it can be seen only on host side on SHARES, LUN etc...
3] What is cache of those storage subsystem?
It Depends if you are FAS2552 is a single or Dual controller 2GB or 4GB respectively and on top of it you can have FLASH CACHE added
4] Can I monitor fragmentation of disks?
Nope you don't have visibility to monitor the fragmentation.
Thanks,
Nayab