NFS Performance Tuning for HP-UX 11.0 and 11i Systems

nfs performance tuning for hp-ux 11.0 and 11i systems page 90

Notes:

Page 90July 22, 2002

How is NFS PV3 different from PV2?

nfs pv2

vs.

nfs pv3

Safe

UnsafeAsynchronous Writes

READDIRPLUS

READDIR/LOOKUPDirectory Traversal

Attributes included

in every reply

Included in LOOKUP

and GETATTR replies

File Attribute Retrieval

32KB

8KB

Maximum Read/Write

Buffer Sizes

11.0 = 1TB

11i = 2TB

2GBMaximum File Size

NFS PV2 NFS PV3ISSUE

Maximum File Size Supported by NFS Client

PV2 uses 32-bit signed integers for file offsets. PV3 uses 64-bit unsigned.

Asynchronous Writes

PV2 originally required all writes to be synchronous. Async writing was later

added to PV2, but in an unsafe fashion (i.e. data loss can occur). PV3 writes

data asynchronously by default and does so using a “safe” method.

Maximum Read/Write Buffer Sizes

PV2 fixed the largest NFS read or write request at 8KB. HP’s PV3 allows 32KB.

File Attribute Retrieval

File and directory attributes are only returned in select replies from a PV2

server. A PV3 server includes attribute information as part of every reply.

Directory Traversal

PV2 uses READDIR to get directory contents and then sends a LOOKUP for each

file to get its attributes. PV3’s READDIRPLUS call combines these functions.