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The past few years have seen some major changes
in Sun hardware. The return of Andy Bechtolsheim has brought forth an
impressive array of new server hardware, and reinvented Sun as an x86
server vendor. But where does that leave the SPARC?
But all is not lost. The SPARC platform still has some kick left, and while that kick may not be in clock speed, it’s certainly
in the threads.
I’ve had a Sun SPARC Enterprise T5120 server in the lab for a few months now, and I’ve found it to be a very solid platform, as expected, and much like its predecessor
based on the “Niagara” T1 processor, it’s very, very good at some tasks, and not so good at others.
[ See my review of Sun’s original, UltraSPARC T1-based server, the Sun Fire T2000. ]
The
reasons for this performance lie in the CPU itself. The T5120 runs the
UltraSPARC T2 processor, which is a single CPU running four, six, or
eight cores. This architecture is a significant departure from the rest
of the industry, and positions these servers to fill specific, highly
transactional roles, foregoing the rest. In that capacity, they do
quite well.
The tale of T2
The
basis of the UltraSPARC T2 design is to fit as much onto the processor
die as possible, decreasing latency and increasing bandwidth to
mainline I/O, such as 10G Ethernet and RAM. In order to achieve this,
Sun has basically produced a “system on a chip” with core-specific
memory controllers, FPU, cryptographic accelerator (SPU, or Stream
Processing Unit), and 4MB L2 cache, along with x8 PCIe and two 10G
Ethernet controllers -- all residing on the CPU die. Each of the eight
discrete cores is positioned to support eight concurrent threads. All
together, this equals a single CPU that uses less than 95W, and appears
to the OS as 64 CPUs – a neat trick.
This
represents the second iteration of Sun’s play in this game, supplanting
the UltraSPARC T1. The T2 has many benefits over the T1, such as the
integrated per-core FPU and crypto units. These two additions erase
some of the math and crypto performance concerns of the T1, while
bumping the top clock speed to 1.4GHz.
But
what does this mean in the real world? Easy — the T2 is a great choice
for highly threaded applications, and a miserable choice for
single-threaded applications. The low clock speed causes
single-threaded apps to chug along, while the eight cores give
multi-threaded apps plenty of room to stretch out. Each thread is still
bound to the 1.4GHz clock speed, but depending on the application, that
doesn’t necessarily equal slower performance.
My
T5120 evaluation unit came with the single, eight-core T2 CPU, 64GB of
RAM, four copper gigabit Ethernet ports, two USB 2.0 ports, three PCI-E
slots (two doubling as 10G Ethernet slots), serial and Ethernet service
processor connections, and redundant power supplies.
Up front, T5120 well equipped for local storage,
as it’s available with as many as four 2.5-inch 10K RPM SAS drives. I’m
not entirely sure why Sun opted for the high concentration of local
disk, as the nominal position of the T5120 is as a compute server, not
a storage server, but given that they had the room, it’s not unwelcome.
When used with ZFS, Sun’s revolutionary new file system,
the internal storage options grow, especially in virtualization
scenarios. It’s easy to see the T5120 supplanting many physical
SPARC-based servers by collapsing their workloads into Solaris
Containers that feed from the T5120’s 64-thread trough.
The other side of
the T5120 is the low power consumption. The CPU runs at less than 95W,
and the server itself runs relatively cool, hence the Sun CoolThreads
designation. Certainly, in comparison to the behemoth Suns of yore, the
T5120 steps lightly with both power consumption and heat generation.
A fix for ILOM
The
management of the T5120 resides largely in the Sun ILOM (Integrated
Lights-Out Manager), which is accessible via a serial and Ethernet
connection. As with most of Sun’s SPARC-based servers, there is no
frame buffer in the server, so the only management options are the
serial console, SSH, or Web-based management tools. It seems to me that
these tools have actually gotten worse over the past few years, as I’ve
found it harder to work with later iterations of the ILOM than those of
just a few years ago. As a case in point, the ILOM for the T5120 was
slow, even when only using SSH, and relatively Byzantine to work with
on both the Web and SSH interfaces. The Web interface looks and feels
like the management interface found on nearly all Sun servers,
SPARC-based or otherwise, with the exception that there’s no console
applet. SSH to the ILOM is the only way to access the console remotely.
After
consulting with Sun regarding the sluggish interface, I received a much
newer firmware revision for the ILOM. Following that upgrade, the
performance of the ILOM was significantly better on both the SSH and
Web interfaces. As of this writing, the T5120s that are shipping now
have this newer version installed. By the numbers, my evaluation of the
management capabilities was running at a solid 7 until the firmware
revision arrived, inching that score into low 8 territory.
Given the effort and care granted to the rest of the server, these issues are rather puzzling, but thankfully could be remedied
with updated firmware, not updated hardware.
Naturally,
the T5120 was built to run Solaris. In my tests, Solaris performed
quite well on a number of standard tasks, such as Web and database work
-- essentially any task that was sufficiently multi-threaded. As
mentioned, the T5120 makes a great virtualization platform for these
same reasons. But Solaris isn’t the only OS that can be run on the
T5120. Ubuntu Server’s SPARC release runs as well. Although I did
encounter some initial Ubuntu-related installation problems, after
those were resolved, Ubuntu 7.10 ran cleanly. It was very interesting
to run ‘top’ on that installation and see 64 CPUs appear, representing
the fact that the UltraSPARC T2 offers each thread of each core as a
separate CPU designation to the OS. Thus, eight cores times eight
threads per core gets us to 64.
The
overall performance of the T5120 under Ubuntu was roughly even with the
performance under Solaris for normal tasks, though there are
significant optimizations for the T2 processor in Solaris that will
result in better FPU and crypto performance, at least for now.
Overall,
the UltraSPARC T2 and the T5120 build upon the hallmarks of the
first-generation UltraSPARC T1-based servers, and remind us that
although the SPARC CPU may have been marginalized in recent years, it
hasn’t surrendered, and may in fact be making a comeback.
Read the original article: http://www.infoworld.com/article/08/03/27/13TC-sun-sparc-t5120_1.html
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