zpool autoexpand property [PSARC/2008/353 Self Review]

[Matthew Ahrens]

Template Version: @(#)sac_nextcase 1.66 04/17/08 SMI
This information is Copyright 2008 Sun Microsystems
1. Introduction
    1.1. Project/Component Working Name:
	 zpool autoexpand property
    1.2. Name of Document Author/Supplier:
	 Author:  George Wilson
    1.3  Date of This Document:
	30 May, 2008
4. Technical Description

A. SUMMARY

This case add a new pool-level proprty, 'autoexpand,' to the existing
zpool property infrastructure (PSARC 2007/342). This property controls
the behavior of pools in the presence of  Dynamic LUN Expansion (PSARC
2006/373).

B. PROBLEM

With the addition of Dynamic LUN Expansion (PSARC 2006/373), Solaris now
publishes  a sysevent when an underlying device is expanded. ZFS has
been enhanced to take advantage of these events and will adjust the pool
based on the new size of the expanded LUN. However, administrators need
the ability to control this behavior on individual pools.

C. PROPOSED SOLUTION

The introduction of the 'autoexpand' will allow administrators the
ability to enable or disable automatic pool expansion when a Dynamic LUN
Expansion event is received.  The syntax for setting the pool property
utilizes the "set" subcommand defined in PSARC 2006/577:

   # zpool set autoexpand=on <pool>
   # zpool create -o autoexpand=on <pool> <device> ..

D. MANPAGE DIFFS

The following text will be added under the "Properties" section:

   autoexpand=on | off

       Controls automatic pool expansion when the underlying LUN is
       grown. If set to "on", the pool will be resized according to the
       size of the expanded device. If the device is part of a mirror or
       raidz then all devices within that mirror/raidz group must be
       expanded before the new space is made available to the pool. The
       default behavior is "off". This property can also be referred to
       by its shortened column name, "expand". 

6. Resources and Schedule
    6.4. Steering Committee requested information
   	6.4.1. Consolidation C-team Name:
		ON
    6.5. ARC review type: Automatic
    6.6. ARC Exposure: open