pNFS: Requirements

1
pNFS Requirements

• 61th IETF DC
• November 10, 2004

2
Now Þ Goal

• Now requested data moves through NFS server
• Goal reply from NFS server enables parallel
  access to diverse storage servers (NFS, iSCSI,
  FC, )

3
pNFS Requirements

• In response to pNFS Problem Statement
• Draft-gibson-pnfs-problem-statement-01.txt
• Bandwidth capacity scaling
• Beyond one network endpoint for file system
• Server bypass for client access to storage
• NFSv4 minor extension desired
• Extensible storage (backend) protocols
• NFSv3, NFSv4, SCSI blocks, SCSI objects

4
pNFS Reqs - NFS extensions

• Industry-wide open standard
• NFSv4 minor extension desired
• No change to existing commands/results
• New operations added via compound
• Complimentary to, no dependence on RDMA

5
pNFS Reqs - Scalability

• Respond to scalable cluster computing
• Scalable bandwidth wrt to total resources
• Aggregate BW to files in one FS, one directory
• Individual BW to single large files
• Employ multiple network endpoints at storage
• Scalable capacity wrt to total resources
• Size of FS, directory, file can scale with storage

6
pNFS Reqs - Interoperability

• pNFS endpoints talk to non-pNFS NFSv4
• Storage protocol interoperability
• Well defined storage protocol standards
• Multiple different storage protocols, extensible
• SBC (SCSI blocks), OSD (SCSI objects), NFSvX
• Separability of storage protocols
• NFSv4 extension operation does not need to
  interpret layout state specific to storage

7
pNFS Reqs - Concurrent Sharing

• Many clients access storage at same time
• At device and file level
• Change visibility can be asserted by client
• Data attribute change visibility not always
  determined
• No assertion of client cache coherence
• Logic modeled on Direct access mode

8
pNFS Reqs - Recovery

• Seek simple semantics to enable less complex
  implementations, interoperability
• Slow recovery permissible, fast recovery possible
• Client recovery may be notify retry
• Retry may be equivalent operation using only
  NFSv4
• Storage operations should be idempotent

9
pNFS Reqs - Security

• Security comparable to NFSv4 allowed
• Security model for storage must be well defined
• Trusted storage environments not ruled out, but
  must be well documented
• Files ACLs consistent over servers
• Objects OSD secure capabilities
• Blocks SAN access control tools (zoning, FC
  ACLs)

10
pNFS Reqs - IANA

• Need to name storage protocols
• Divide namespace
• 1) Reserved for this standard to define
• 2) Reserved for vendor defined
• 3) Open for in-house customer defined, non-unique
• Storage naming defined by storage protocol