Acopia 101

Acopia present a virtual file server, and tier files to slower disks according to policy.

Presentation volume aka direct volume.  No meta data maintained by Acopia.

Managed Volume has associated metadata volume.  eg many unixhome_shareX to 
make up a large volume.   Underlaying share ought to be hidden as windows share (req to share it), so that user don't write directly to it (which skew the metadata).   NFS share for the underlaying share farm volume should be exported to the acopia only, so that other nfs client can't mount directly to it.

Presentation vol wrap around many managed volume.

The managed volume needs to be exported by CIFS (hidden share help reduce 
clutter).  But NFS don't need additional export by Acopia, as acopia does the
proxy for the file access for NFS.  CIFS require forwarding the req to the file system handling the req.


Managed volume, NFS access should have 32k page size instead of default 8k to
improve performance.  

Max-file need to be pre-determined ahead of time (esp when managed
volume will be wrapped by presentation volume).  
This is like allocating inode for a unix FS (acopia need this to manage
multi-protocol).  It can be enlarged, but reduction only back to an internal 
pre-allocated number only.  Changing number requires disabling and re-enabling the presentation volume for the changes to take effect 
(Win client disconnect; NFS also depend on this flip-flop to ensure don't 
get stale file handle).

Rule of thumb for allocation max-file count is to see if FS will
hold large or small files, divide FS size by file size to see
how many file handles are needed.  eg, 32TB fs, 80M file handles is good.
For 2 TB fs, default of 4M max-file is probably okay, but allocating 8M 
would ensure won't grow out of file handle "inode" problem.  (if avg file size is less than 250k).


.acopia shows up in underlaying share farm volume 
to tell which acopia owns it.  it will be hidden from the 
final managed volume and user shouldn't see it.

In places where they have more than 1 pair of acopia, other acopia will 
see such marker to see who is managing or own the volume.

acopia rely on its internal db to keep track of where all files are, thus all access must be made via the acopia.
EMC Rainfinity pepper the target file system with files everywhere, such file points to where rainfinity have moved a given file to.  seems rather messy for the user.  

Similar Technologies

Other Hierarchical Storage Management (HSM) systems besides F5 Acopia ARX: