April 02, 2004
Windows Opens Wider For Storage Needs
By Terry Sweeney
Microsoft has added more storage-related capabilities to Windows Server 2003
to makes SANs less complex to deploy and manage.
Among the new features that will be unveiled at next week's Storage Networking
World tradeshow is Microsoft's Fibre Channel Information Tool. The tool
identifies storage components and gathers component information across multiple
storage fabrics and from multiple vendors, according to Claude Lorenson,
Microsoft's technical product manager for storage technologies for Windows
Server 2003. The tool gets information about drivers and firmware in use, and
reduces the need for third-party tools, he added.
Microsoft is also releasing storage tracing support on Windows 2003, which
consolidates tracing and logging mechanisms and downloads them to a single file.
This in turn is supposed to be an easier way to debug or troubleshoot. It's also
preferable than trying to do a live debugging of SAN, which can impact network
performance, Lorenson explained.
Tracing support will be available on Service Pack 1 for Windows Server 2003 and
will be supported by Adaptec, Emulex, Intel, LSI Logic and QLogic, Microsoft
The vendor is also adding to its IP-SAN support with a data center edition of
its iSCSI architecture for Window Server 2003. Microsoft has already certified13
vendors for the data center edition.
Microsoft is also releasing Multipath I/O to provide multiple links between
Windows servers and storage components for improved failover and reliability,
which till now has been largely Fibre Channel's domain.
"A lot of customers have isolated servers not attached to their SAN, and they'd
like them to be," said Lorenson. "But the cost of running a Fibre Channel link
or a host bus adapter is not very economical for one or two servers."
All this tracks very closely with what Microsoft has been doing in the storage
sector during the last 18 months--making it easier to use Windows 2003 in SAN
environments, said Nancy Marrone-Hurley, senior analyst with the Enterprise
Storage Group. "None of them are momentous new technologies, just new features
that make it easier to implement SANs and manage in the Windows OS," she added.
Copyright © 2004 CMP Media LLC. | STORAGE PIPELINE
Storage UPDATE--Windows 2003 Storport--April 5, 2004
Date: 4/5/2004 5:21:36 AM Eastern Standard Time
by Jerry Cochran, firstname.lastname@example.org
Storage I/O Made Better with Windows 2003 Storport
Windows storage I/O has grown a little long in the tooth since the days of
Windows NT 3.1 more than 10 years ago. The Windows storage I/O driver layer
(i.e., the SCSI miniport, aka SCSIport) has been in need of a serious overhaul
for some time. Microsoft made the necessary investment in Windows Server 2003,
which provides a revamped storage I/O layer that will take Windows
applications to the next level of storage performance and functionality.
For as long as I can remember, people have complained about the fact that NT
understands only SCSI and doesn't understand IDE, RAID, or complex storage
connections such as Fibre Channel or Internet SCSI (iSCSI). This limitation is
largely attributable to the traditional SCSIport driver. In the early days,
Microsoft bet that SCSI would become the disk interface of choice. That bet paid
off, but times have since changed and direct-attached SCSI drives are no longer
the only game in town for Windows systems. The SCSIport driver doesn't provide
the performance, configuration flexibility, and manageability that today's
RAID-enabled, Fibre Channel-based Storage Area Network (SAN) and Network
Attached Storage (NAS) environments require.
The SCSIport driver has certain architectural limitations, including a maximum
of 254 I/O requests per SCSI adapter, sequential
(or half-duplex) I/O functions (in other words, either issuing I/O requests or
completing them, but not doing both at the same time),
excessive load at high IRQ levels, high buffer-processing overhead, and I/O
queue management limitations. Storage hardware vendors can and have worked
around these problems by developing their own drivers (many have developed their
own storage filter drivers), but those drivers are proprietary and difficult to
support. These shortcomings aren't easily fixed and have signaled a need for
Microsoft to design from scratch a solution that meets the demands of today's
technologies and applications.
Microsoft designed the Storport driver with modern storage I/O requirements and
the shortcomings of SCSIport in mind. Storport
specifically addresses each problem I mention above while maintaining a degree
of backward compatibility to ease the transition from SCSIport to Storport for
vendors and customers.
To address SCSIport's half-duplex limitation, Storport supports synchronous I/O
functioning (i.e., full duplex). Thus, Storport can
issue and complete I/O requests simultaneously. To alleviate SCSIport's
excessive loading at high IRQ levels, Storport adds a new parallel routine that
handles much of the IRQ processing overhead (such as building scatter/gather
lists for I/O
requests) before sending the command to hardware. Storport also reduces buffer
processing overhead by providing driver developers with flexible options for
To resolve SCSIport's 254 outstanding I/O request limit per adapter, Storport
imposes no per-adapter limit. Instead, Storport
limits the number of outstanding I/O requests per LUN to 254. This improvement
provides flexibility and much more headroom for
high-performance storage systems, such as Fibre Channel SANs. Of course, the
onus is then on storage vendors to develop controllers and infrastructure to
handle this I/O load.
Storport provides better I/O queue management than SCSIport (which really can't
control I/O queuing at all) by implementing I/O queue control functions (e.g.,
pause, resume, busy, ready) on a device, adapter, and LUN basis. By addressing
specific SCSIport limitations, Storport provides an architecture that meets the
demands of next-generation storage technology.
Storport doesn't stop there, however. Microsoft looked beyond the problems with
SCSIport to the future of storage technology. This focus on the future drove
additional functionality into Storport. New features include enhanced error
handling, Fibre Channel link handling and channel management, better Windows
clustering support, and deferred procedure call (DPC) support for extended
Microsoft hopes that Storport will make developers' lives easier as well as
making Windows storage easier to support and manage. The Windows Driver
Development Kit (DDK) includes tools that vendors can use to migrate their
SCSIport drivers to Storport. Early Microsoft tests show that Storport is paying
off in terms of performance.
Microsoft claims that Storport is 30 percent to 50 percent more efficient than
SCSIport and can handle more I/Os per second at a lower CPU utilization.
As you look to future storage purchases for your Windows systems, make sure to
ask your favorite vendor whether their products support Storport. Leveraging
Storport promises benefits for storage vendors, Microsoft, and customers alike.
Copyright 2004, Penton Media, Inc.