The new role of LTO-5:
LTFS vs. tar
HPA Tech Retreat
Palm Springs
February 17, 2011
©2011 Cache-A Corporation
The issues with using tape

Data Portability


Ease of Use


Command-line vs. GUI
Self-Describing


Standard for format on tape
Directory of a tape’s contents
Linear Nature

Not random access

Can’t freely delete content and recover space
©2011 Cache-A Corporation
#2
Data Portability

The majority of tape-based solutions use
proprietary formats

Only one open format has been available – tar

LTFS now adds a second open format

HP & IBM Interop proven in the demo room
©2011 Cache-A Corporation
#3
Ease of Use

tar has been command-line driven and mostly
limited to tech-weenies

LTFS offers accessibility from normal file tools
including:

Windows Explorer

Mac OSX Finder
©2011 Cache-A Corporation
#4
Self-Describing Tape – a bit of history


1987: SuperMac DataStream (Mac)
1992: QIC with QFA (DOS)
1996: DatMan (Windows)

LTO (2000)
 2004-2007:
Quantum A-Series (networked)

2008: Cache-A tar (networked)

2010: LTFS (Linux, Mac, Windows)
©2011 Cache-A Corporation
#5
tar – a bit of history

Originally in Unix in the late 1970’s

tape archive

Established POSIX.1-1988 standard in 1988

POSIX.1-2001 revised extended tar a.k.a. “pax” format


Unlimited pathname length

Unlimited character set encoding

Date/Time, Symlink, User/Group improvements
Mac, Windows, Unix and Linux versions available
©2011 Cache-A Corporation
#6
tar Format
tarball
©2011 Cache-A Corporation
#7
Cache-A tar Format
Cache-A Appliance
Disk
Catalog
Database
TOC
TOC
TOC
TOC
TOC
Additional
Metadata
©2011 Cache-A Corporation
#8
LTFS Format
©2011 Cache-A Corporation
#9
LTFS Format
©2011 Cache-A Corporation
#10
Cache-A LTFS Format
Additional
Metadata
Cache-A Appliance
Disk
Catalog
TOC
TOC
TOC
TOC
TOC
TOC
©2011 Cache-A Corporation
#11
LTFS Issues

Newly Minted, work to be done

Not all file names supported

Tape spanning not supported

LTO-5 Only

Long delays to update index upon eject

Many ops cause tape thrashing
©2011 Cache-A Corporation
#12
LTFS does not work like a hard disk

The Good News: LTFS Looks like Disk

The Bad News: LTFS Looks like Disk

If you treat it like Disk, you will have problems

File fragmentation, performance issues


i.e. Auto-Save
Multi-file operations

i.e. Icon View
©2011 Cache-A Corporation
#13
Cache-A LTFS implementation

Include Cache-A TOC on tape

Include TOC in Catalog

Include “URL encoding” to support
real-world file naming

Handle linear transactions behind the scenes

Plans for continued future enhancements
©2011 Cache-A Corporation
#14
Format Comparison
baseline
LTFS tar
Cachetar ALTFS

Portable, Cross Platform





Self-Describing





Easy-to-Use




©2011 Cache-A Corporation
#15
Format Comparison
baseline
LTFS tar
Cachetar ALTFS

Single File Restore





Multi-tape Volumes





Library Option




©2011 Cache-A Corporation
#16
Format Comparison
baseline
LTFS tar
Cachetar ALTFS

Networked, Multi-user





No Client-side Software





Handles all file names


©2011 Cache-A Corporation
#17

Format Comparison
baseline
LTFS tar
Cachetar ALTFS

Multi-tape Search





Search Restore





Technical Support




©2011 Cache-A Corporation
#18
Summary

LTFS is the only Self-Describing, Open Solution
Available

tar is More Mature and More Ubiquitous but not
Self-Describing or Easy-to-use

Appliance implementations like Cache-A’s can
improve both – neither is complete on their own
©2011 Cache-A Corporation
#19
Thank You
©2011 Cache-A Corporation
#20