Storage Strategies Special Edition - Tuesday, November 18, 2003

Disk-to-Disk-to-Tape: Four Top-Notch Bundles
By Jon William Toigo

Cobbling together solutions for disk-to-disk-to-tape may actually drive
the cost of Tier 2 disk above the price of solution sets that combine
the functionality.

A friend of mine, who is also CTO for a leading storage vendor, likes
to tell a story about a recent sales call. An amusing (and probably
apocryphal) tale, I repeat it here only to help frame a broader
discussion of Disk-to-Disk-to-Tape (DDT) platforms and their potential
role in both large enterprises and small-to-medium-sized businesses
(SMBs). (Story continues below)

Seems that a sales person representing the vendor in New York was
having some difficulty selling the company's DDT platform to a prospect
and asked the CTO to intervene.

"This customer, who was looking at our enhanced backup platform, now
says that he has decided to go with 'Jay-BOD' instead," the sales guy
lamented. "Can you maybe talk to him about it or something?"

My friend agreed and phoned the prospect, "Hi, I'm [John Smith], CTO of
XYZ Corporation, and I understand that you are evaluating our enhanced
backup product."

With a thick-tongued Brooklyn lilt, the customer responded "Well, thank
you for calling, but I am afraid that we have decided to go with JBOD…"

My friend retorted, "Well, you have good reason to be afraid..."

"Are you threatening me?" the customer snapped back, to which my friend
quickly clarified, "No, it is a common misperception that CTO means
Chief Threat Officer. However, I am the Chief Technology Officer, and
I think there are several good technical reasons for you to be afraid
about making the choice for Just a Bunch of Disk (JBODs) versus our

Well, to hear my friend tell it, complete with "wise guy" gestures and
accents, the story is side-splittingly funny. Truth be told, however,
there are some good reasons to go with Disk-to-Disk-to-Tape, as many
companies are discovering.

DDT provides a way to expedite backup by first copying data directly
from one tier of disks to another, then enabling tape backups as a
separate operation without concern about backup windows. The second
tier of disk (whether provided by JBODs or some enhanced disk platform)
can serve both as a staging area for the backup -- a cache, if you will
-- where useful data preparation can be performed, and also as a
"nearline" repository for data that can be used to expedite discrete
file or data block restores.

As a pre-tape backup "staging area," the functionality of Tier 2 disk
may be augmented with technology like Avamar Technology's commonality
factoring, which can be used to reduce the volume of backup data to a
fraction of its original size. Data hosted on Tier 2 can also be
expunged of "contraband files" like MP3s or AVIs, checked for virus
signatures, compressed, and/or encrypted -- all prior to backup. And,
when open data naming schemes are fully developed, Tier 2 may also
serve as a location for placing descriptive headers onto files so they
can be migrated to appropriate tape resources such as Write-Once Read
Many (WORM) volumes or to optical disk based on data preservation and
retention requirements.

All in all, there are good technical reasons for deploying DDT. The
industry knows it and has responded with a variety of proprietary DDT
platforms at the high end, and a plethora of inexpensive JBOD solutions
at the low end of the product line. Sorting through the options can be
a dizzying experience, especially in the absence of meaningful head-to-
head solution comparisons.

My friend's argument that simple JBOD-based solutions may not be the
best approach has some merit. Tier 2 disk, after all, is serving as a
surrogate repository for mission-critical data. To perform this role
even minimally well, some sort of RAID is probably required as a
stopgap against the traditional foibles of disk.

RAID implementations range from software-based to hardware-assisted
approaches (e.g., solutions from Promise Technology and certain Adaptec
products), to full-out intelligent controller-based approaches (like
Intel's well-respected high-end RAID controllers). All RAIDs are not
created equal, and you pretty much get what you pay for.

Augmenting Tier 2 JBOD with RAID capability is an absolute minimum
configuration requirement for DDT. Additionally, you will find that
some investment will need to be made in software to derive real value
from the approach. You may need NDMP support for back-end Tier 2-to-
tape interconnects, or something more exotic if you are writing to WORM
or optical. And, of course, in addition to all the file scanning, data
naming, and other useful purposes to which you may wish to harness the
solution, you will need to purchase extra secret sauce technology.

In the final analysis, cobbling all of these features and functions
together may actually drive the cost of Tier 2 disk above the price of
solution sets that actually bundle the functionality. Four top-notch
bundles that I am familiar with are Quantum's DX-100, Avamar
Technologies' AXION, Arkivio's auto-stor, and the soon to ship iStoRA
from Breece Hill.

DX100 is a nice improvement on the groundbreaking DX30 platform
released by Quantum a couple of years ago. DX30 was essentially a tape
target surrogate, designed to drop into existing tape backup
environments and add speeds and feeds to the laborious process of
backup. DX100 retains this disk-as-tape paradigm (for now) but
improves on the capacity (up to 64 TB of disk), performance and pricing
of its solution. Wedded to its MAKO PX720 Tape libraries, DX100
delivers as much bang for the buck as large-scale tape backup shops may
ever need.

By contrast, Avamar's AXION and Arkivo's auto-stor are more than tape
emulation targets in a DDT configuration. Each solution brings a "data
lifecycle management in a box" play to the market that challenges the
depth and capability of EMC's primordial offering in this space:

AXION, which comes in two flavors -- "E" for branch offices and smaller
settings (1.2 TB of usable disk per unit) and "M" for larger enterprise
settings (scalable to exabytes of storage, according to the vendor) --
migrates data after eliminating redundant data sequences, enabling
companies to derive better capacity utilitization from their disk
investments. The technology also takes a page from EMC and provides
content addressable storage to track data location as it migrates from
platform to platform. Currently, the solution ships with all software
and hardware supplied by the vendor, though it is conceivable for CEO
Kevin Daly to eventually separate the two so that other hardware
platforms can be supported.

Arkivio's solution provides some interesting functionality for policy
and access-frequency-based data migration, so that your less frequently
accessed data doesn't live on your most expensive gear. The technology
is being wedded to various low-cost disk array platforms, like Nexsan's
ATA-based ATAboy2 arrays, to facilitate a one-stop shop for hardware
and software.

Meanwhile, Breece Hill, under the guidance of CEO Phil Pascarelli, is
about to go to market with one of the first of a burgeoning class of
disk/tape hybrid products designed to give backup relief to the SMB
market: a product currently called iStoRA. At a meeting with
Pascarelli's team in Louisville, CO recently, I was impressed by the
combination disk array (1 TB of Serial ATA RAID) and half-inch tape
autoloader (2 TB raw capacity) -- and by the value-add supplied by
Avail Solutions Integrity software, which has been integrated with the
box. At its anticipated price point of less than $10K, this appliance
holds the potential for setting the bar in drop-in, policy-based, DDT
solutions for the SMB market.

Based on conversations with other tape vendors at the Fall Storage
Networking World conference in Orlando, there are a lot more products
on the horizon to meet the needs of this space. If you have any input
to offer on DDT, or experiences -- positive or negative -- with these
products, drop me a line at jtoigo@intnet.net.

Copyright 2003 101communications LLC

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Last Modified: March 9, 2008