ChucksProjects

From Linux NFS

Latest revision as of 16:19, 4 December 2007

Stuff I'm playing with, thinking about, or watching admiringly...

Mount

Testing and documentation

• Add real unit testing
• Construct a set of specifications for mount behavior
• Rewrite nfs(5)
• Test "-o remount" -- handled by /usr/sbin/mount instead of /sbin/mount.nfs?

UI clean up

• Make error reporting more useful
  • Some error messages are too specific ("RPC Error: RPC program not available" is meaningless to most users)
  • Some error messages are too general ("mount.nfs: mount failed" doesn't explain how to rectify the problem)
• Complete internationalization

New features

• Implement support for IPv6
• Implement support for server failover options
• Add scalable mounting (more efficient use of network resources; mountd connection caching)
• Properly implement break-back retries

More notes

NFS support for IPv6 networking

• Get the delegation / NLM stuff working
• Rewrite the referral logic in user-space (DNS resolution can be needed to handle an NFSv4 referral)
• Review svcauth_unix stuff to remove open-coded IPv4 address dependencies
• Track where we are with user-space tools and libraries
• Existing NFS IPv6 code for the client

NFS client performance tools

• Replace jiffies-based timestamps with ktime in the RPC client for more precise latency measurement
• Consider adding existing Python utilities to nfs-utils
• Update vmstat and iostat tools to provide statistics about NFS mount points
• Construct new tools that provide fine-grained data about NFS mount points

Eliminate BKL from NFS client

• Remove BKL dependency from attribute cache
• Remove BKL usage from XDR layer
• Remove BKL usage from RPC client and GSS
• Eliminate BKL in NFS client proper

From OmniOutliner

• Bruce found that the BKL is held while calling normal XDR encoding and decoding functions
  • Why did I miss the existence BKL around XDR encoding?
  • Generic xdr.c: look for anything caching an xdr_buf, especially during decode
  • Still need an audit of NFSv4 XDR
    • Copying state ids
    • Migration - file handles can change
    • Theoretically the client ID is in danger as well
• Trond has RCU'd lots of stuff shared with NFSv4 XDR
• and also the RPC auth cache
• Radix trees are now RCU -- so write path locking might be relaxed

Alternate socket-based transport implementations

• One UDP socket per client
• Two TCP sockets per rpc_clnt (one for sync, one for async requests; could be done by an NFS client change instead)
• One TCP socket per client CPU
• One TCP socket per server, shared by mount points (that's probably an NFS client change, not a transport change)
• DMA-engine based TCP socket transport
• SCTP-based transport (server-side switch and NFS on SCTP spec needed for that)

Rebuild the NFS server and client XDR layer from the ground up

• More complete type checking and error reporting
• Each function called with a simplified virtual API
• All functions re-entrant so we can remove the BKL

NFS client build testing

• Builds kernel with "allmodconfig" and "allyesconfig"
• Automated - no user intervention once started
• Tests all patches in a series
• Later add more static analysis for each patch
• Need to add post-analysis tool that compares the build logs
• Need to eliminate as many spurious warnings generated by the tool chain as possible

More notes

Advanced file sync tool

• multi-purpose generic file system syncer - a file synchronization tool that runs on most Unix-flavored operating systems
• one-way or bidirectional data synchronization
• syncs file changes periodically or continuously
• supports disconnected operation (later playback of changes)
• can use advanced file system features to improve efficiency
• the basic idea is to use an inotify-like mechanism to make the detection of file and directory modification more efficient

More notes

Unifying storage management on Linux

• A easy-to-use graphical tool that can manage storage devices and pools, and file systems
• Includes a wizard (like Roxio or Toast) that can start different applications depending on what is to be accomplished
• Make it easy to create, manage, and back up very large data storage pools
• Make it easy to export and secure data
• Provide a framework for thinking about and documenting data management

More notes

Linux De-duplication appliance

• Provide high capacity near-line storage for inexpensive disk-based backup
• Based on content-addressable storage on top of RAID 6
• Looks like one or more very large OSD LUNs or a very large NFS server

More notes

Object Storage Devices