zfs discuss - Oct 2007 - Changes to default output from post S10 zfs list

This information is Copyright 2007 Sun Microsystems

1. Introduction
   1.1. Project/Component Working Name:
        zfs list default output
   1.2. Name of Document Author/Supplier:
        Author:  Rich Morris
   1.3  Date of This Document:
        19 October, 2007

4. Technical Description
This case changes the default output of the post S10 zfs list
command.  The stability of the flags are committed, and the
release binding is patch/micro.

A. INTRODUCTION

In S10, when run without any options, the zfs list command lists
all zfs datasets.  This includes all filesystems, volumes, and
snapshots.

This case changes the post S10 zfs list command to omit snapshots
by default.  Instead, zfs list will display only filesystems and
volumes.  A new inheritable property will permit fine-grained
control of the zfs list output for each dataset.

The default behavior of zfs list in S10 will not change.

B. DESCRIPTION

The zfs list command outputs the property information for the
given datasets in tabular form.  In S10, zfs datasets of all
types are displayed by default.  The -t option provides a way
to specify one or more types to display, For example, specifying
"-t snapshot,volume" displays only snapshots and volumes.

On systems with thousands of datasets, snapshot information can
flood the output, making the default zfs list command less useful
in the case where the user is not interested in information about
snapshots.  One example is jurassic-x4600.sfbay which has around
1700 zfs filesystems but more than 55000 snapshots.

This case adds a new inheritable dataset property named "listsnaps"
which is off by default.  When the value of this property is set
to on then zfs list displays snapshot information for this dataset.
If the -r option is specified then zfs list also displays snapshot
information for all of its child datasets that have this property
set to on.

This case adds a new "-t all" option to zfs list.  To get zfs list
to include snapshot info on a post S10 system: set "listsnaps" to
on in the root dataset(s) or specify "-t all"

The -t option to the zfs list command takes precedence over the
value of the "listsnaps" property.  zfs list -t snapshot displays
all snapshots including those associated with filesystems where
the "listsnaps" property is off.

The "listsnaps" property does not change the behavior of any
subcommand of the zfs command other than list.

C. MANPAGE CHANGES

% diff zfs.1 zfs.new
437,438c437
<          The type of dataset: "filesystem", "volume",
"snapshot",
<          or "clone".
---
>          The type of dataset: "filesystem", "volume",
or "snapshot".
641a641,646
>      listsnaps=on | off
>
>        Controls whether info about snapshots associated with
>        this dataset is output when zfs list is run without
>        the -t option.  The default value is "off".
>
1239,1240c1244,1246
<          name. By default, all datasets are displayed and contain
<          the following fields:
---
>          name. By default, all filesystems and volumes are displayed.
>          Snapshots are displayed if the "listsnaps" property is
on
>          (the default is off).  The following fields are displayed:
1313c1319
<                         tem",   "snapshot"   or  
"volume". For
---
>                         tem",   "snapshot",  
"volume", or "all". For
1942c1948,1949
<      volumes in the system.
---
>      volumes in the system.  Snapshots are displayed if the
"listsnaps"
>      property is on (the default is off).
2017a2025
>        pool/home/bob  listsnaps      off                    default
6. Resources and Schedule
   6.4. Steering Committee requested information
       6.4.1. Consolidation C-team Name:
               ON
   6.5. ARC review type: FastTrack
   6.6. ARC Exposure: open