October 2, 2000

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Storage Area Networks
Everything In Its Own Place

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HighGround Helps Users Manage And Control Storage (9/25/00) InternetWeek: Enterprise Storage (9/25/00)

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On the storage side, Compaq brought two StorageWorks RAID Array 4100 disk enclosures, each of which offers 12 drive bays. One is equipped with 18-Gbyte Ultra3 (Ultra160) SCSI hard drives; the other has the same-size drives, but uses Ultra2 SCSI disks. Compaq uses the same drive enclosures in the disk enclosures that it uses for internal storage in the latest ProLiant series. The disks are configured as eight logical units (LUNs), four on each disk enclosure, managed by a Compaq RA4000 SAN controller unit.

For backup, Compaq brought a StorageWorks TL891 minilibrary, which contains one 5-Mbyte per second (native) DLT drive and 35-Gbyte (native) capacity tapes. The SCSI-based library connects to the FC-AL switch using Compaq's new modular data router, which is a 1U-high Fibre Channel-to-SCSI with a single FC port and two SCSI connections.

There are different administrative tools for different parts of the SAN, such as the intuitive StorageWorks Command Console for configuring the FC-AL switch; it's a server-side product that runs on a server connected to the switch, and provides a command-line and Web-based interface to configure the switch and the LUNs. A separate utility provides local and remote management (via Ethernet) of the Fibre Channel host bus adapters.

Both of these utilities may be launched from within Compaq's Integrated Management Extended Edition (CIM-XE) management application, and they can roll alerts to CIM-XE to be handled. For a test, we configured Command Console to fire a thermal alert at 20 degrees Celsius; the alert immediately fired and percolated up to CIM-XE, which then notified us remotely of the problem.

The entire RA4100 SAN worked perfectly, but because Compaq doesn't configure it for high availability or redundancy, we were unable to test or verify any of those features.

Compaq's second product, its midsize StorageWorks MA8000 SAN, is more comprehensive--not only more scalable, but with higher-end management tools and the ability to support non-x86-based servers. The MA8000 is Compaq's midrange SAN; the company also makes a higher-end product, the MA12000.

The MA8000 is built around a Fibre Channel fabric switch. Compaq brought two eight-port switches, al-though 16-port switches are also available. The Switch/8 is Simple Network Management Protocol (SNMP)-enabled, has redundant power and cooling, and can be managed via an intuitive Web-based management suite. Compaq connects the two switches in a fully parallel arrangement with two host bus adapters in each server and dual connections to each system. There are no cross-connects between the parallel Fibre Channel networks, which provides the ultimate in redundancy for fault tolerance.

For servers, the Compaq team used the same systems as with the RA4100 SAN test: a ProLiant 8500 running Windows 2000 Server and two other ProLiant servers running Linux and Windows 2000. To demonstrate that the MA8000 SAN is designed to support non-x86 systems, the team brought and connected a Sun Microsystems Ultra5 workstation running Solaris 7, equipped with dual SBus-based FCE-1063 Fibre Channel host bus adapters from JNI Corp. According to Compaq, the MA8000 also supports AIX, HP-UX, Irix, NetWare, OpenVMS, Tru64 Unix, and Windows NT.

For storage, Compaq's MA8000 RAID controller unit drives up to six SCSI channels with a maximum of 12 drives per controller. When new firmware for the MA8000 ships, that limitation will be raised to 14 drives per controller. For this test, the company chose to bring its SW4254 disk arrays, each of which can drive as many as 14 one-inch Ultra2 SCSI devices. The MA8000 can support six SW4254 arrays, for a total of 72 disks, with the potential to upgrade to 84 disks when the firmware is revised later this year.

The Compaq team brought only a single SW4254, equipped with 14 18.2-Gbyte drives. The company also moved the same TL891 tape library and Modular Data Router, which it used for the RA4100 SAN, over to the MA8000 SAN.

The redundancy and high-availability features built into the MA8000 system are impressive. The MA8000 controller includes multiple, hot-pluggable rechargeable battery units for maintaining the RAID subsystem, as well as an environmental monitor and multiple N+1 power supplies and fans.

The system controller contains dual Fibre Channel connections, and is configured to run them both in parallel, shifting all traffic from one port to another in the event of a fault on the Fibre Channel network.

To provide automatic host bus adapter failover on the servers, a pricey software agent called SANworks Secure Path must be installed on each machine: Secure Path is priced at $4,000 per Windows NT or Windows 2000 server and $6,000 for each Sun server connected directly to the SAN.

Another impressive high-availability feature was the MA8000's ability to create a pool of global hot-spare drives that can be on any SCSI channel on the SAN. If a RAID 5 array or RAID 1 mirror set, created to service a single server, experiences a drive failure, the SAN automatically al-locates a spare drive to that array.

In our tests, we created a pool of several hot spares, and then rapidly disabled RAID 1-and RAID 5-based logical units by physically pulling the drives; we could see the global hot spares being allocated to replace them.

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