Comparison of NFS vs. others
From Linux NFS
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# maps well to Unix VFS semantics (except for caching) | # maps well to Unix VFS semantics (except for caching) | ||
# protocol easy to understand by stripping file protocol to its minimum | # protocol easy to understand by stripping file protocol to its minimum | ||
+ | # Leverages ONC-RPC's authentication model for free, and good, security | ||
# Unicode | # Unicode | ||
Revision as of 12:42, 6 December 2005
Here is a description comparing NFS and other similar technologies, found at this page: [1]
Contents |
CIFS
Strengths
- Huge installed client base (not just Windows),
- good, open source server implementation available (Samba!),
- token management (oplock) and referral ("dfs") semantics are a good compromise between usefulness and simplicity
- the key part of the filesystem protocol (mostly) documented, rich file open semantics map well to Windows and related OSs,
- kerberos security integration and RPC integration
- broader in scope (print, ACL, browsing etc.) than other filesystem protocols
- optional PDU signing above the RPC allowing maximal flexibility
- Unicode
- high performance
- huge amount of loosely related management/administrative function available via various DCE RPC calls
- efficient PDUs (small frame headers, less wasted bandwidth)
Weaknesses
- the extended protocol poorly documented,
- not an IETF standard
- elements of older protocol dialects still needed adding to complexity of implementations
- protocol needs addition of lock migration/recovery and support for new transport mechanisms (e.g. RDMA)
- ACL support - although useful is hard to understand
- (item j above) management/admistrative calls are proprietary
NFSv3
Strengths
- relatively simple to implement
- maps well to Unix VFS semantics (except for caching)
- protocol easy to understand by stripping file protocol to its minimum
- Leverages ONC-RPC's authentication model for free, and good, security
- Unicode
Weaknesses
- statelessness of core protocol causes caching problems
- few Windows NFS clients installed
- maps poorly to Windows operating system API
- poor security (forcing it into lower layers if at all)
- not a standard (informational description published by Sun as informational RFC)
- relatively weak open source server implementation (at least compared to Samba and AFS) has scalability problems
- implementing many protocols needed to get CIFS equivalent e.g. lock manager, mount and port mapping protocol, SunRPC, NIS, ONC extensions (some proprietary)
- WebNFS enhancements partially implemented adding to some confusion
NFSv4
Strengths
- on track to be an IETF standard
- improved recovery (lock migration)
- supports Windows file sharing semantics better than NFS v3 did
- safe file caching
Weaknesses
- few clients
- perceived lack of Microsoft interest
- the existing prototype open source implementation is tricky to integrate into current Linux kernels
- protocol is moving target (it is not quite done yet)
- too late?
- complex
DAFS
Strengths
- Addition of RDMA to NFS style protocol, (probable) high performance in clusters and server farms.
- (see NFS v4)
Weaknesses
- unproven, lack of client support, perceived competition with NFS v4
- (see NFS v4)
HTTP/WebDAV
Strengths
- official standard
- broadly implemented
- well suited to internet
- active standardization work - protocol will improve
Weaknesses
- frame headers are large (high % of frame size is wasted)
- security integration not optimal
- slow
- not a complete match to either Linux VFS or Win2K IFS API requirements
NCP(Netware)
Strengths
- NDS integration
- good match for Windows
- good installed base on older systems
Weaknesses
- Proprietary
- poorly documented
- not a standard
- complex, with lots of dialects
- future clients questionable
AFS/DFS
Strengths
- sophisticated distributed caching (token management)
- DCE integration (including Kerberos and RPC)
- standardized by OpenGroup
Weakness
- lack of clients
- bulky, slow Windows clients
- server integration with Unix operating systems and server filesystem is complicated
- most implementations were expensive complex to implement
Coda
Strengths
- disconnected support
Weaknesses
- Lack of commercial implementations
- lack of Windows clients
- not well understood
Lustre
(help?)
Strengths
- Fully distributed.
- Excellent performance.
Weaknesses
- Poor community interaction.
- lack of clients.
GFS
(help?)
Strengths
- Fully distributed.
Weaknesses
- Needs heavy-duty, not-standardized cluster management system.
- Linux-only (?)
GPFS
Strengths
- Good performance.
- Stable, well-tested.
Weaknesses
- Commercial-only.
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