It's no secret in the industry that competition between Network
Appliance Inc. (NetApp) and EMC Corp. is fierce. As NetApp pushes
into the midrange
storage area network (SAN) space with its
FAS3000 line, and EMC brushes up Celerra in NetApp's traditional
network attached storage (NAS) territory,
it's growing more heated than ever.
Last week, NetApp published the results of a test it
commissioned from Lionbridge Technologies Inc.'s VeriTest labs,
claiming that the newest FAS3000 model, the 3070, out-performed the
newest high-end Clariion, the CX3-80. The test measured an
OLTP workload using 3.2 terabytes (TB) of
400 GB
logical unit numbers (LUN) on 200
Fibre Channel (FC) disks within each array,
and found that the total aggregate throughput performance for 8
KB random reads and writes on the 3070 topped out at 31,109
input/output per second (IOPS) vs. 28,352 IOPS on the
Clariion.
"NetApp delivers better performance and lower latency [than
EMC]," trumpeted NetApp in a press release.
@29074 Hold the phone, was EMC's response. In an email to
SearchStorage.com, EMC officials wrote, "The VeriTest performance
test was run using a small fraction of the available capacity of
the system … out of the 28.8 TB of raw capacity, they are using
only 3.2 TB or 11.1%." Furthermore, EMC added, "This sub-15%
utilization avoids [a] massive performance degradation [on] …
NetApp's SANs."
In a white paper based on its own internal laboratory testing,
EMC's own charts showed NetApp's 3050 with higher initial
performance than the Clariion CX3-40, which EMC argues is the more
comparable product. But, the paper argued, as utilization of the
SAN increased beyond 15% of the total system capacity, performance
degraded more sharply on the NetApp system than on the Clariion
system.
A he-said-she-said battle over product claims is hardly new,
analysts said, but it is unusual for EMC to respond in such detail
about performance claims. "It shows that the midmarket is a huge
open battleground," said Brad O'Neill, senior analyst with the
Taneja Group. "That's the clearest thing that can be discerned from
this."
IDC numbers released in September showed that NetApp is, in some
ways, encroaching on EMC's SAN territory. According to the report,
NetApp surpassed EMC in storage terabytes shipped, at 68,898 to
EMC's 66,581. EMC, meanwhile, argued that Dell Inc.'s shipments of
EMC storage weren't factored in to that report, and EMC remained
highest in revenue.
What's the bottom line?
NetApp is making strides, according to users and analysts, but
they also said there is a nugget of truth to EMC's report.
The issue centers around NetApp's Write Anywhere File Layout
(WAFL), the file system at the heart of NetApp's storage devices,
whether SAN or NAS, Fibre Channel or
iSCSI. WAFL is a log-structured file system
(LFS). WAFL was actually first conceived in order to speed file
system performance over traditional
CIFS and
Network File System (NFS) methods, in which
disk heads must seek out disk locations that are optimal for
multiblock read operations later on, and then write the block to
the platters. Log-structured file systems, on the other hand,
append all writes to a consecutive stream of blocks (the log),
allowing writes to disk to happen faster.
However, there are two possible inhibitions to performance over
a "pure" block-level access system under WAFL: first, blocks must
pass through a file system "layer" on their way in and out; and
second, as systems grow larger, the log grows continuously, leading
to a possible slowdown in performance as systems grow.
But for many users, particularly in the midrange where
performance is not as crucial as the high end, WAFL provides a
number of distinct advantages over traditional block- and
file-level systems. Chief among these advantages is the ability to
natively serve any protocol, whether block- or file based, whether
Fibre Channel or iSCSI -- something EMC is still catching up on.
NetApp is also widely regarded as the first pioneer of snapshots, a
feature that's also part and parcel of the WAFL system.
"Although WAFL theoretically presents a performance issue in
block-level systems because it is another layer for block-level
access to go through", said Brian Garrett, technical director of
the Enteprise Storage Group (ESG) Lab, "a unified approach enables
Netapp to have a single product line that supports both block and
file in the same product line. A unified approach also provides
simplified access to performance and capacity optimized WAFL,
features like snapshots, writeable snapshots (FlexClones) and thin
provisioning (FlexVols)".
Others predict that it's only a matter of time before NetApp
comes out with direct block-level access as well.
"Any time there's any extra code in the middle, so to speak,
somewhere, you have to pay the piper," said Arun Taneja, founder
and analyst with the Taneja Group. "At some point in time, NetApp
will find a way to go to the block [level] without even the
nanosecond it spends now in WAFL."
NetApp declined to comment on whether or not it had any such
plans and also declined requests to specifically discuss the
technical aspects of the WAFL system and performance.
Performance doesn't necessarily tell the whole story
According to Michael Israel, senior vice president at Six Flags
Theme Parks Inc., his company swears by NetApp and the 3000 series.
Each amusement park boots commodity servers from Hewlett-Packard
Co. (HP) off of FAS 3020s and 3050s, depending on the size of the
operation, and replicates that data to a central data center, where
Israel said he is in the process of upgrading to the 3070 for
capacity reasons.
"It's just a matter of swapping out the [controller] heads" to
upgrade, Israel said. "That's one of the things I like about
NetApp."
Other things he likes: the ability to run iSCSI for booting his
servers and for some SQL database applications in the same system
as file and print shares for corporate headquarters, and
snapshots.
Israel admitted that for his purposes, performance wasn't a
priority. In a "former life" at a billion-dollar financial
institution, (Israel declined to name it) just before he joined Six
Flags eight months ago, Israel said he himself had tested EMC's
CX700 against a NetApp 3050, as well as boxes from HP and Sun
Microsystems Inc. Head to head, Israel said, the boxes performed
similarly, but the company still went with the Clariion for 15 TB
of Oracle and Sybase databases and Unix servers, and purchased the
NetApp to run alongside it for NAS and Windows applications.
"It was more of a reputation thing than anything else -- it was
a comfort feeling," Israel said. "At the time, EMC had eons of
customer references running Unix systems, and NetApp wasn't quite
there."
Nowadays, Israel said, "We don't have that kind of budget leeway
at Six Flags." He added that EMC systems would have been much more
expensive for his operation than NetApp -- another of the primary
reasons Six Flags is a NetApp shop.
"At some point, customers may become impervious to the back and
forth over products between vendors," O'Neill said. "In the end,
raw performance numbers are nothing more than a useful data point
-- every user is different and users are often more or less
familiar with one vendor."
In other words, O'Neill said, both EMC and NetApp's performance
claims are probably "100% true -- but 5% relevant."