NFSv4 D. Noveck, Ed.
Internet-Draft EMC
Intended status: Informational P. Shivam
Expires: September 22, 2013 C. Lever
B. Baker
ORACLE
March 21, 2013
NFSv4 migration: Implementation experience and spec issues to resolve
draft-ietf-nfsv4-migration-issues-03
Abstract
The migration feature of NFSv4 provides for moving responsibility for
a single filesystem from one server to another, without disruption to
clients. Recent implementation experience has shown problems in the
existing specification for this feature. This document discusses the
issues which have arisen, explores the options available for curing
the issues, and explains the choices made in updating the NFSv4.0 and
NFSv4.1 specifications, to address migration.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 22, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
Noveck, et al. Expires September 22, 2013 [Page 1]
Internet-Draft nfsv4-migr-issues March 2013
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. NFSv4.0 Implementation Experience . . . . . . . . . . . . . . 4
3.1. Implementation issues . . . . . . . . . . . . . . . . . . 4
3.1.1. Failure to free migrated state on client reboot . . . 4
3.1.2. Server reboots resulting in a confused lease
situation . . . . . . . . . . . . . . . . . . . . . . 5
3.1.3. Client complexity issues . . . . . . . . . . . . . . 6
3.2. Sources of Protocol difficulties . . . . . . . . . . . . 8
3.2.1. Issues with nfs_client_id4 generation and use . . . . 8
3.2.2. Issues with lease proliferation . . . . . . . . . . . 9
4. Issues to be resolved in NFSv4.0 . . . . . . . . . . . . . . 10
4.1. Possible changes to nfs_client_id4 client-string . . . . 10
4.2. Possible changes to handle differing nfs_client_id4
string values . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Other issues within migration-state sections . . . . . . 12
4.4. Issues within other sections . . . . . . . . . . . . . . 12
5. Proposed resolution of NFSv4.0 protocol difficulties . . . . 13
5.1. Proposed changes: nfs_client_id4 client-string . . . . . 13
5.2. Proposed changes: merged (vs. synchronized) leases . . . 13
5.3. Other proposed changes to migration-state sections . . . 15
5.3.1. Proposed changes: Client ID migration . . . . . . . . 15
5.3.2. Proposed changes: Callback re-establishment . . . . . 16
5.3.3. Proposed changes: NFS4ERR_LEASE_MOVED rework . . . . 16
5.4. Proposed changes to other sections . . . . . . . . . . . 17
5.4.1. Proposed changes: callback update . . . . . . . . . . 17
5.4.2. Proposed changes: clientid4 handling . . . . . . . . 17
5.4.3. Proposed changes: NFS4ERR_CLID_INUSE . . . . . . . . 19
6. Results of proposed changes for NFSv4.0 . . . . . . . . . . . 19
6.1. Results: Failure to free migrated state on client reboot 20
datatracker.ietf.org