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Top ten IP storage tips

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If you're thinking about going down the IP path, here's some advice from early adopters to consider.

1 Design carefully. Sure, this is true for any storage area network (SAN), but it's especially important because IP performance might be a bottleneck if there are large distances or many remote locations involved.
2 Get your storage and networking experts together, and make them play nice.
3 Make sure you're starting with at least a Gigabit Ethernet backbone to ensure adequate performance, especially if you're planning on using IP to handle your primary storage.
4 Out-of-the-box Gigabit Ethernet NICs work just fine for most applications; you'll want to consider TOE or other kinds of interface adapters only for the applications with really specialized or high-performance needs.
5 Separate the IP SAN traffic on its own VLAN, for both performance and security reasons.
6 Understand what you'll need to do to your applications to make them happy on iSCSI--making registry changes, pointing SQL Server files to the correct locations, etc. While Fibre Channel customers have long had to deal with this, these issues generally aren't part of the direct-attached world, and there might be a learning curve involved for IT staffers.
7 Take advantage of the fact that many vendors in the IP space are small and hungry and really want your business. Some customers have demanded--and received--benefits, including extra consulting and support and even money-back guarantees.
8 Make sure your IP solution of choice supports all the platforms you need--Linux and Unix iSCSI drivers aren't as popular as those for Microsoft.
9 Start small, with a couple of applications and/or servers, and grow from there.
10 Don't be afraid. Despite some vendor-driven FUD out there, every single person we talked to says they're happy they went down the IP road and that things are working out just fine.
The rumors about IP storage really are true, early adopters say. The technology is fairly easy to set up and manage, and performance is fine for many types of applications--assuming that the IP-based networks or storage components are designed and/or implemented properly.

IP storage brings many benefits to the data center, including lower costs compared to Fibre Channel (FC) storage area network (SAN) products. We talked to eight organizations, some of which have been using IP SANs--or IP-based storage in general--for a year or more. Three are using IP as their primary storage mechanism for everything from database to e-mail and customer billing applications; one is using IP for backup and restore only; two are using IP for primary storage and backup; another is using its IP setup as a file server to replace a failing network-attached storage (NAS) box. One organization, Sandia National Laboratories, is still in testing mode and hasn't begun using its IP SAN in production.

In the user world, some installations have mixed FC and IP protocols--as opposed to pure FCIP or iSCSI. This is often due to older storage boxes--or even fabrics--that may use FC to link to other IP-based components of a SAN. This is the situation at the Cancer Therapy Research Center (CTRC) in San Antonio, TX, which is using older, FC-based disks with an IP-based storage router to get its planned ROI out of the storage boxes.

Users' own definitions of what constitutes IP storage or an IP SAN can vary widely. Some are using IP storage over WANs or are using iSCSI over IP or Ethernet networks to connect servers and arrays. Some are doing IP within one data center; others are using the protocol to connect far-flung storage boxes and servers.

Most of the IP implementations are still fairly small at this point, with an average of 3TB to 6TB of actual storage. In most cases, this is a fraction of the storage still in direct-attached mode or even on an FC SAN.

Five of the eight organizations are using an FC SAN in addition to IP, or at least started with FC. All have different ideas about connecting--or not connecting--the two worlds. The global law firm Clifford Chance is hoping to connect its Fibre and IP SANs in the next year or so. The Public Broadcasting Service (PBS) plans to use both for different applications for the foreseeable future--Fibre for its high-performance, transactional needs and IP for pretty much everything else--with hopes that it can someday manage the two from one management suite. Mortgage provider HomeBanc and water-purification supplier Zenon Environmental will continue to use their FC gear for one dedicated application that's already on the system, but will use IP for almost everything else.

iSCSI for primary storage
There are many reasons to get involved with IP storage. The CTRC implemented an IP network approximately two years ago and hasn't looked back. The CTRC offers radiation and oncology services to major hospitals in four locations, and serves roughly 200 patients each day. Its two primary facilities are 22 miles apart.

The center has seen a huge growth in its storage needs, driven by digital imaging requirements. Many types of scans--CT, MRI and others--move around the network on a regular basis. In 2001, the organization built a new main campus, which was an opportunity to redesign its major IT infrastructure, says Mike Luter, CTO. The major criteria was availability and reliability, because "to have someone miss or have to reschedule a radiation treatment is simply unacceptable."

Luter says it was clear from the get-go they'd need Gigabit Ethernet to provide adequate bandwidth for its images and other files. So while they were at it, CTRC decided to kill many birds--iSCSI storage, voice over IP telephony and an application server at both data centers--with one stone. And with this setup, one IT staffer can now handle all of a user's needs.

Of its 45 major servers--mostly Compaq--some two-thirds are on the IP SAN, with approximately 7.5TB of total storage. There's a spare Compaq DL360 g2 at each location, and there's synchronous mirroring of data for business continuity.

The setup includes two EMC Clariion 4700s, with Cisco SN 5428 storage routers. The 4700s are actually Fibre-based, so they link to the 5428s via Fibre, and then the IP-based 5428s link to the backbone network.

This was first published in April 2004

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