Transcript NetApp PowerPoint Template

AFS and NFS
… 20 Years Later
Mike Kazar
[email protected]
June 2005
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Overview
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Inspired by talk by Brian Pawlowski (beepy)
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presented to a bunch of folks at IBM
including lots of AFS people
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What were AFS’s goals? NFS’s goals?
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Innovation on client and server ends
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Storage management
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Then and now
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Some thoughts about the future
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Lessons learned
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Questions
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Who Am I?
 Part
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of AFS design team, with
Bob Sidebotham (Rx, Volumes)
Mike West (Server)
Sherri Nichols (VLDB &c)
M. Satyanarayanan (prototype RPC)
Dave Nichols (prototype client)
 Coded
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cache manager
kernel port of Rx
 Now
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parts of AFS
at NetApp
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AFS Goals in 1984
 Distributed
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connect lots of workstations together
 Scalability
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did I mention *lots*?
key approach was caching
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the fastest RPC is the one you don’t make
 Security
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needed isolation from random students
 Management
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was an afterthought
but turned out to be critical
volumes
volume *moves*
mirroring
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Key points from Beepy’s talk
 What
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 If
is NFS?
IETF standard
bundled with all Unix/Linux systems
available on nearly everything
heterogeneous (systems, FSes)
NFS is the answer, what was the question?
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Stick a fork in it…
FTAM
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Clients, Servers, an’ ‘at
 So,
why am I smiling?
 Clients,
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Protocols, and Servers
Different goals for each
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Clients
 OS
integration
 Bug-free
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or you get calls all the time
 Reference
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implementation
helps portability a great deal
even though porting still lots of work
“Vnode” layers in Windows, AIX, Solaris, &c
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Protocols
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Where NFS Really Shines
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Public protocol spec
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everyone knows they can implement it
Interoperability tests (Connectathon)
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formally, helps certify who’s in the game
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informally, helps communication!
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set goals for future work
Reference implementation
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as education tool
Where NFS sucks
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cache coherence
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how did they blow this in NFS version 4?
but still relatively minor
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few applications use DSM
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locking makes most things work
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Servers
 Where
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AFS Shines
Data management
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global name space
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cell name spaces
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transparent move
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transparent load balancing mirrors
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flexibly allocated volumes
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snapshots / clones
Usable ACLs
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suprisingly
caching
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using memory caches today
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Today
 NFS
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is the protocol of choice
open licensing made it a no-brainer
simplicity also a plus for growth
 Some
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Snapshots on NetApp filers
flexible volumes
non-transparent moves
 Some
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AFS data management available today
AFS data management available “soon”
transparent move
load balancing mirrors
multiple cells
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OnTAP NG Architecture
Q1
Location independence
acct random
Q2
P1
P2
Atomic move, snapshots
Class of service
Mirrors, caches
SpinServer
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SpinServer
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SpinServer
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acct
Q1
Q2
P1
Unix
workstation
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Windows
desktop
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Windows
desktop
random
P2
UNIX
workstation
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Architecture Detail
ONTAP / NG:
2-Stage Distributed
File System
1.
2.
3.
Request switched to
appropriate back-end
IP-based cluster
network
Client Access
Client Access
Gigabit Ethernet
Gigabit Ethernet
Network Function
Network Function
• TCP termination
• VLDB lookup
• Protocol translation
to SpinFS
• TCP termination
• VLDB lookup
• Protocol translation
to SpinFS
SpinFS Protocol
X
No client code changes
Disk Function
• Caching
• Locking
Fibre Channel
Gigabit
Ethernet
Switch
Disk Function
• Caching
• Locking
Fibre Channel
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History as Knobs
 No
knobs
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initial filers
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one volume, period
Suns, &c
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network parameters, exports, not much else
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 Too
many knobs
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 Just
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tracking thousands of volumes
figuring out restores
where do I create a new volume?
right
self-managing based on guidance
eg. this part of the name space is a database
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The Future
 Policy-based
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management
declare part of name space “database”
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inherit RAID level, drive speed
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referenced abstractly
constraint engine
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moves data around
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with limited system impact
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when desired
tied to delegation
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sub-admins tied to name space parts
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sub-admins constrained by resource limits
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The Future
 Ties
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to historical data
what volumes are heavily loaded, and when?
which volumes grow and shrink?
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what variation in size
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what variation in load
what volumes were on this server?
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backup database issue
charge-back
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The Future
 Quality
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of Service
Important for managing applications
but no common framework
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eg: to connnect job controller and storage
so, need to start somewhere
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virtual servers, perhaps
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per volume?
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priorities vs. guaranteed bandwidth or ops
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Lessons Learned
 Perfection
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is highly overrated
POSIX semantics never really required
Huge effort in DCE/DFS
 Universities
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are similar to enterprises
pointless politics and empire building
24x7 operation
availability and reliability
coordination with users nearly impossible
slightly cheaper
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Lessons Learned
 Technology
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20 years to get AFS volume concept out
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only happened because Blake Lewis and Ed.
Zayas went to NetApp
More for transparent moves
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Spinnaker acquisition
 Beware
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second system syndrome
and ignoring customer requirements
DCE/DFS was nearly complete waste of time
 Morris’s
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Transfer is Hard
point about 3rd systems
independence from inventor is critical
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throw out bad ideas
allows simplification
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Lessons Learned
 No
one pays attention to system management
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but it is critical to any technology deployment
QoS is part of this
scaling is part of this (managing resource pools)
centralized error reporting
dynamic reconfiguration
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 Don’t
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be greedy!
know where your real value is
know how to get help
IBM lived in fear that Sun would productize AFS!
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so bungled licensing
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