What's all the buzz about TCP/IP offload engines?
It's about higher data transfer
speeds at lower cost. In a recent test, a server with an Alacritech
Gigabit Ethernet accelerator card was hooked to a Nishan IP storage
switch and connected to a Hitachi Freedom storage array across a
single Gigabit Ethernet network. The result: iSCSI data transfer
rates in excess of 219 MB/s with less than 8% CPU utilization. Top
rates for Fibre Channel are slightly under 200 MB/s, with CPU
utilizations ranging from 5% to 10%.
Until recently, only Alacritech was
shipping TOEs. All of its products list for under $1,000 per board,
which is much lower than the cost of adding servers or adopting
Fibre Channel, which can cost several hundred thousand dollars.
In February, 2002, Intel became the
first major player in the market, introducing its PRO/1000 T IP
Storage Adapter, which should be available as you read this for
$695. While Intel hasn't done any public tests along the lines of
the Alacritech/HDS/Nishan demo, Travis Vigil says they have reduced
the CPU load for a Pentium III server to under 5%, compared to
virtually 100% with no TOE.
While there are some differences in
the approaches taken by Intel and Alactritech, the differences are
less significant at this point than the similarities.
"Intel entering the market is
a validation of the TCP offload process," says Jamie Gruener,
senior analyst for storage with Yankee Group Inc., Boston, MA, who
cautions that "we're in a validation phase."
The basic idea behind TOEs is to
let servers work more effectively in data intensive environments
where companies run core business apps across multiple networks via
TCP/IP. As the data load goes up, the server processing loads can
become unacceptably high. TOE devices offload the TCP/IP processing
that's performed on a host server to an ASIC chip on the adapter.
Although the error correcting in the TCP layer that used to drag
down TCP/IP traffic is still done on the host, offloading the
processing to the ASIC chip promises to dramatically reduce server
bottlenecks and speed backup times.
Galen Schreck, an analyst with
Forrester Research in Cambridge, MA, thinks TOEs are promising, and
may be essential to achieve acceptable storage-over-IP performance.
"Protocols like iSCSI that depend upon high-speed access to
networked storage will begin to drain performance from applications
at higher speeds," he says.
Schreck says there are a number of
niches where TCP offload technology will have immediate appeal -
applications like storage or Web serving where processing TCP
packets tends to take CPU time away from the applications running on
a server, for example.
TOE users are rare right now
because most TOE vendors are still in the development stage. San
Jose, CA-based Alacritech Inc. may soon be joined by some others,
such as QLogic, Aliso Viejo, CA, which is beta testing product. But
a half-dozen or more companies are rushing to bring TOE-type
products to market and most refuse to disclose their plans.
Early Adopters
For companies that have deployed TOEs, there is cautious optimism
about the ability of the technology to deliver. David Zanesco,
network manager at Madison National Life in Madison, WI, started
using TOEs from Alacritech about six months ago to overcome the slow
performance of the company's backup server. Zanesco says his shop is
predominantly based on Token Ring networking and in setting up the
backup server, he opted for an additional Ethernet segment,
installing an HP ProCurve switch to handle the interchange between
the two sections.
Zanesco says that nightly backups
were taking 12 hours when he was running them on the Token Ring
alone. After installing an Alacritech 100x4 Quad-Port Server
Adapter, backup times were reduced sharply.
Even with the added complexity of
moving data between Ethernet and Token Ring, Zanesco says his
operation reduced backup time to about four hours. The backup server
with the Alacritech TOE now handles all backups, including data from
Freedom, an insurance industry accounting package provided by
Freedom Group, Cedar Rapids, IA, that's widely used by insurers and
financial service operations like Madison. "The database is
enormous, with thousands of files, so ensuring that a thorough and
complete backup is done every night is critical," says Zanesco.
In addition, Madison must back up thousands of more familiar Word
and Excel files.
Zanesco says he also
looked at a range of products from Madge, Olicom, IBM, and 3Com, but
Alacritech had the most cost-effective option. Zanesco says
Alacritech's TOE provides higher performance than other products he
had researched and that he went with Alacritech because it offered
aggressive pricing, a fast card, and a convincing argument for
offloading the server CPU.
Rick Halbardier, a
project coordinator in the IT Department for Washoe County in
Nevada, also had a positive experience with Alacritech. Washoe
County stores about 3.2TB of data across 112 servers. After
installing an Alacritech 100x4 Quad-Port Server Adapter and an
Alacritech 100x2 Dual-Port Server Adapter, the operation's usual
10-hour backup process was reduced to just two hours. Prior to
installing the Alacritech network adapters, the servers were set up
in a point-to-point 100-Mbps Fast Ethernet connection. Now, the
county's backup server is point-to-multipoint, and the DHCP is
point-to-point using Fast Ethernet smart trunking on two
connections.
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TOEs make servers more efficient |
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Halbardier estimated that the improved
network performance will save $25,000 to $30,000 annually. In
addition, he says it will eliminate the need to budget up to
$100,000 for new server hardware.
How should other potential
customers analyze and select TOE technology? Unfortunately, beyond
the experience of a handful of Alacritech customers, there's little
hard experience on which to base opinions. Jeff White, senior
storage engineer at Imation's storage lab in Oakdale, MN, says the
lab started testing Alacritech's products and may follow that with
an examination of beta product from QLogic. He says there are no
real benchmark tests for TOEs at this point but, "they seem to
do what vendors say they will do."
Opinions on TOEs vary widely among
analysts. Steve Duplessie, analyst with Enterprise Storage Group
Inc., Milford, MA, is very bullish on TOE technology and predicts
that it will become ubiquitous in the not too distant future. But
other analysts disagree.
"Storage traffic is up for
grabs when it comes to TOEs," says Gruener. "I'm on the
fence until the industry as a whole provides serious performance
statistics to support the idea that TCP/IP offload engines can
really solve the problem. We need to performance testing with backup
and other applications." Gruener adds that InfiniBand could
transfer the entire TCP bottleneck into the network.
Schreck points out that there are
many other competing technologies in the network performance space:
routing optimization, caching, compression, and SSL offload to name
a few. "Companies like Sockeye, Network Physics, F5, and Intel
have various appliances that compete for the same budget dollars -
and none of those use TOEs," he says.
He predicts that TOEs will survive
in some form and become incorporated into numerous products with
higher-level functions, such as NAS boxes, iSCSI cards, server-class
gigabit NICs, and Web performance accelerators. As examples, he
cites Redline Networks' Web performance accelerator and BlueArc's
networked storage. "I wouldn't imagine that firms would go
shopping for TOEs as a standalone item," he says. "In the
long run, I expect TOE technology to sink below the waterline - like
the alternator in your car. You need it, but you don't buy it as a
separate purchase - nor do you really care about who made it.''
For now, while TOEs are appealing,
storage managers may want to wait at least six months. Alacritech,
the pioneer, can still cite only a handful of users. Test data is
almost nonexistent. And there are fundamental questions about where
TOEs will fit architecturally.
To be sure, TOE technology seems to
offer more bang for the buck, but wrong turns, even if initially
inexpensive, can turn out to be costly in the long run. By later
this year there should be more early adopters with experiences to
review and many more vendors delivering product - surely a better
environment for making informed decisions.
