ns2 project in gujarat
ns2 project in Gujarat a key objective in designing VIP-FS is portability
If the file system is to be an extension to message passing
libraries, it must be portable across different libraries;
as such, the design must employ ns2 project in gujarat only features
which are common to most, if not all, message passing
libraries. Also, it must be capable of co-existing
with other (Unix based) data mariagment or network
file systems that may be employed Further, it must
\le capable of operating in ns2 project in gujarat heterogeneous distributed
system environments. the InterfaceItyer, the virtual parallel file (VPF) layer, and the
device driver (IDD) layer E’igure 1 illustrates
the logical configuration of VIP-FS The Interface layer provides a variety of file access
abstractions to the application program. For example,
I t may be a simple interface composed of standard
iinix open, close, read, write fiinclions ns2 project in gujarat Or, the file
system may accept, information describing the mapping
of a parallel file to a partitioned data doniain,
and transparently arbitrate access according to this
napping. The VPF layer defines ns2 project in gujarat and maintains a unified
global view of all file system components It pro\ides
1 he Interface layer with a single file image, allowing
each parallel file to be viewed as a single large file organized
as a sequential stream of bytes It achieves this
tiy organizing and coordinating access to the IIID’s
files in such a way that a global, ns2 project in gujarat parallel file is constructed
whose component stripes art’ composed of the
independent IDD files Any specification of a file offset
by the Interface layer is resolved by the VPF into
;in IDD address, file ID, and ID11 file offset
As shown, the IDD layer is built upon and conimuriicates
with the local host’s file system. It manages
each file as an independent non-parallel file and pro-
\ides a stateless abstraction to the VPF layer above ‘rhus, the IDD layer arts as the mediator betwemi the
local host file system and the VPF layer nication between layers within and across hosts is accomplished
through the use of message-passing library
primitives. In the following section ns2 project in gujarat we discuss the implementation
of VIP-FS. The discussion proceeds in a bottomup
manner, from the IDD layer to the Interface layer.
We begin with a brief description of the initialization
and configuration process. As ns2 project in gujarat its primary function, the IDD layer is responsible
for communicating with the local file system and providing
a stateless interface to the VIP-FS layer. The
IDD layer is implemented in VIP-FS as a set of Unix
processes. The IDD supports a non-parallel (i.e., Unix stream)
view of files. It does not have knowledge of the logical
parallel file or of mapping functions; that is, it carries
no knowledge of how data is distributed among the
disk set or among the processors. All ns2 project in gujarat communication
with the IDD will take place through a icommunications
daemon. Requests will identify the requesting
taskid, the desired operation IDD processes receive file access requests from the
VPF layer in the form of messages sent through the
message-passing library being used. Requests can be
made for any of the standard Unix file ns2 project in gujarat access operations
such as open, close, read, write, etc.. The IDD
process performs the requested operatioii and sends
an appropriate response back to the ns2 project in gujarat VPF layer. The
IDD process has no notion of any global file space.