1. Filesystem Caching (FS-Cache)
Steve Dickson
Kernel Engineer

2. What is FS-Cachefs
Caches remote data on local disk
Persistent after unmounts and reboots
Improves server scalability
Reduces network traffic
Completely transparent to application

3. Using FS-Cachefs with NFS
The 'fsc' mount option activates the caching
Example: mount -o fsc server:/export /mnt/server
Only reads are cached.
This does NOT mean read-only filesystem
Cache disabled when file is open for write.
Cachefilesd needs to running
user_xattr need to be on the caching directory
tune2fs -o user_xattr /dev/hdxN
/usr/share/doc/cachefilesd*/howto.txt

4. RHEL5 Architecture Overview
Network
NFS
CacheFiles
FS-Cache
ext3

5. NFS Version 4
Steve Dickson
Kernel Engineer

6. NFSv4 Protocol Feature List
Firewall Friendlier
Mount and locking protocols are integrated into protocol
Compound Procedures
Multiple operations sent in one Over-The -Write message.
Strings are used for User/Group ids
rpc.idmapd – maps to Linux UIDs on server and client.
Integrated Access Control List (ACL)
NT style ACLs
Pseudo File System
Shared server namespace
Putfh, lookup, getattr
Mandatory locks
nohide when exporting
client needs to support callbacks for delegation
also similar to Opportunistic Locks used by CIFS

7. NFS Architecture NFS4 Architecture Application mountd idmapd lockd
Kernel Space
User Level
ext3
ext3
ext3
GFS
System Call
kNFSD
NFS4
(-t nfs4)
NFS
kNFSD4
The components for NFS
Note: not rpc.mountd
Note: the addition of rpc.idmapd
See how Secure NFS is really a RPC thing...
RPC/SVC
Ethernet

8. Secure NFS
Steve Dickson
Kernel Engineer

9. Used by ALL three NFS versions Use the ‘-o sec=krb5’ mount option
Secure NFS
Used by ALL three NFS versions
Use the ‘-o sec=krb5’ mount option
Uses GSS-API cryptographic method.
Three Kerberos 5 security levels
Authentication, Integrity, Privacy
Daemons Handle contexts
rpc.gssd – Client contexts
rpc.svcgssd – Server contexts
krb5, krb5i krb5p

10. NFS Architecture NFS4 Architecture Secure NFS Application mountd
svcgssd
gssd
idmapd
lockd
Kernel Space
User Level
ext3
ext3
ext3
GFS
System Call
kNFSD
NFS4
NFS
kNFSD4
The components for NFS
Note: not rpc.mountd
Note: the addition of rpc.idmapd
See how Secure NFS is really a RPC thing...
RPC/SVC
Secure RPC
Ethernet