I am sponsoring this case for Eric Diven. Timeout is set for May 7, 2008.
This note replaces my earlier attempt to start this case. I've updated the
functional spec, and removed my earlier "one-pager" file from the materials
directory. All email in the 'mail' file prior to this is superceded by this
note.
Release binding is Minor.
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:
SAM-QFS Tar Format Update
1.2. Name of Document Author/Supplier:
Author: Eric Diven
1.3 Date of This Document:
29 April, 2008
4. Technical Description
Proposal:
Allow SAM-QFS stager and arcopy tools to read and write a pax
compliant tar format.
Detail:
The SAM-QFS daemons 'sam-stagerd' and 'sam-arcopy' are currently
reading and writing a tape format that is a slightly modified version
of a format used by a very old version of GNU tar. The older GNU tar
format was modified for SAM-QFS because it didn't satify the project's
needs for file size and long file names.
The SAM-QFS team would like to modify these daemons to read and write
a pax compliant tar format, as described in [1].
The default behavior will call for 'sam-arcopy' to continue writing
the old-style tar format. The new format can be selected by setting a
new 'tar_format = posix' option in the existing SAM-QFS config file,
/etc/opt/SUNWsamfs/defaults.conf.
The 'sam-stagerd' daemon will read the tape by validating the magic in
the tar header. If the old GNU magic of "ustar[sp][sp][null]" is
found then the old format is read. If the new magic of
"ustar[null]00" is found then the new format will be read.
If an old version of SAM-QFS attempts to read a new pax format tar
header it will declare the file 'damaged', which is an existing
SAM-QFS concept. No legacy patch is planned, and this incompatibility
will be documented for customers.
The SAM-QFS 'sls -D' command and option, a SAM-QFS-aware version of
ls(1), will be modified to report the tape format used for the given
file, if that file is currently on tape. It will make this decision
based on an available bit in the on-disk inode, which is currently
zeroed on existing SAM-QFS filesystems.
A new versioned library, libpax_xhdr.so, will be added to SAM-QFS.
This library is created by abstracting the tar-specific bits out of
'stager' and 'arcopy'.
Ultimately, this change puts the SAM-QFS team in a position where they
could retire their old version of the GNU tar command, called star.
This star command is used only in disaster-recovery scenarios, and is
rarely used.
Deliverables:
/opt/SUNWsamfs/sbin/sam-stagerd
/opt/SUNWsamfs/sbin/sam-arcopy
/opt/SUNWsamfs/bin/sls
/opt/SUNWsamfs/lib/libpax_xhdr.so.1
/opt/SUNWsamfs/lib/libpax_xhdr.so -> /opt/SUNWsamfs/lib/libpax_xhdr.so.1
Exported Interfaces:
sam-stagerd Committed Commandline syntax
sam-arcopy Committed Commandline syntax
sls Committed Commandline syntax
libpax_xhdr Committed
Imported Interfaces:
libiconv
References:
[1] http://www.opengroup.org/onlinepubs/009695399/utilities/pax.html
6. Resources and Schedule
6.4. Steering Committee requested information
6.4.1. Consolidation C-team Name:
N/A
6.5. ARC review type: FastTrack
6.6. ARC Exposure: open
