IBM Revamps Midrange, High-End Storage Arrays
October 18, 2004 Alex Woodie
IBM raised the bar in the midrange and high-end storage array business last week when it introduced two new disk subsystems that work with OS/400 and every other major server platform. The new TotalStorage DS6000, which begins at under $100,000, can scale from about 300 GB to 67 TB; it fits in a 3U form factor in its base configuration. The refrigerator-sized DS8000, based on IBM’s p5 Model 570 Unix server, can expand up to 192 TB, but IBM says its architecture scales past a petabyte.
The DS6000 line is capable of storing from 292 GB to 67.2 TB of data, which is possible by stringing together up to 14 DS6000 storage expansion enclosures, each of which holds 16 disk drives, for a maximum of 224 drives. Each 16-disk enclosure has a 3U form factor, enabling the devices to be placed in the same cabinet as a rack-mounted server, as opposed to making room in the data center for a large stand-alone array. DS6000 users can mix and match their choice of three different Fibre Channel disk drives: 73 GB, 15K RPM; 146 GB, 10K RPM; or 300 GB, 10K RPM.
To prevent overheating in such a small device, IBM borrowed a page from its BladeCenter design specs and used a specialized version of the company’s PowerPC processor, the 750GX running at 1 GHz, which was introduced at the end of last year. The 750GX was designed to be used in specialized and embedded applications, and it features a beefed up L2 memory cache and advanced power dissipation capabilities, IBM says. Each DS6000 enclosure features eight host ports and eight storage ports, and each port is based on the 2 GB/sec Fibre Channel standard. The DS6000 has redundant, mirrored RAID controllers and supports RAID levels 5 and 10; each controller has 2 GB of cache memory, which is backed up with battery power.
The DS6000 supports a wide range of servers, including IBM’s eServer line, including the iSeries, pSeries, zSeries, and xSeries. IBM is also supporting competing Unix operating systems, including the Solaris boxes from Sun Microsystems and Fujitsu Solaris boxes; Hewlett-Packard HP-UX, OpenVMS, and Tru64; Apple Macintosh G4 and G5 servers; and various Linuxes. On the Intel platform, the DS6000 supports Windows, Linux, and NetWare. IBM also says that operating systems in the VMware GSX Server or ESX Server virtual machine partitioning environment are supported, too.
On the OS/400 platform, the DS6000 array supports OS/400 V5R2 and i5/OS V5R3. Supported servers (those that support Fibre Channel) include the iSeries Models 270 and 8XX and the new eServer i5 5XX series. Some DS6000 features are not supported on the iSeries, including the DS Open API (CIM Agent), the DS CLI, and the SDD, although IBM notes that multi-path support is provided in i5/OS V5R3.
On the software side, the DS6000 provides a Web-based GUI for configuration and management tasks, IBM’s FlashCopy point-in-time backup capabilities, and mirroring capabilities. One of the cool things about the DS6000 is that it can be used to mirror data between older ESS 800 “Shark” arrays, as well as the new high-end DS8000 disk arrays just announced. IBM says the DS6000 and the DS8000 arrays share 97 percent of the same microcode, enabling this mirroring capability, and providing a good upgrade path from the DS6000 to the DS8000.
While IBM touts the smallness of the DS6000 compared with the hugeness of competing storage arrays manufactured by EMC and Hitachi, the DS8000 itself is a refrigerator-sized box that weighs more than a ton, and is obviously not in the same class as the DS6000.
The DS8000 disk arrays are based on IBM’s new p5 Unix servers, and each array is equipped with two mirrored, rack-mounted p5 570 servers (which fit in a 4U form factor). The DS8100 comes with mirrored two-way p5 570s, while the DS8300 comes with mirrored four-way p5 570s. Like the DS6000, the DS8000 line expands incrementally with 16-disk enclosures, and the DS8000 line uses the same Fibre Channel disks as the DS6000. The DS8100 can have up to 24 of these enclosures, giving it a maximum storage capacity of 115 TB, while the DS8300 supports up to 640 drives, across 40 enclosures, providing a maximum storage capacity of 192 TB.
However, this architecture can scale much higher than 192 TB. IBM says the “Seascape” architecture that the original Tarpon and Shark arrays represented, and that the new DS6000 and DS8000 arrays continue, has the capacity to scale up to 1,000 terabytes, or one petabyte. This scalability is not important for commercial customers, but it has implications for IBM’s many supercomputer customers, who have very large data sets. The DS8100 has from four to 64 server ports, while the DS8300 supports up to 128 host ports. The DS8100 has from two to 16 host adapters, while the DS8300 supports up to 32 host adapters. Each adapter on these arrays connects to a four-port, 2 GB/sec Fibre Channel interface; if FICON is used on a mainframe, there are only two host adapter interfaces.
IBM says it introduced new caching technology with the DS8000 series that continually “self-tunes” to adapt to different workloads. For high-capacity workloads, the cache in the DS8300 can be scaled up from 32 GB (the minimum) to 256 GB (the maximum) to improve I/O performance. The DS8100’s cache starts at 16 GB and scales up to 128 GB.
The coolest part about the new DS8300 is its support for logical partitioning, which is based on the technology that debuted in the iSeries years ago and is now called the Virtualization Engine by IBM on the i5 and p5 platforms. Only the DS8300 has this logical partitioning activated (it is not offered on the DS8100, but for no good technical reason); this partitioning allows users to carve out up to two separate logical partitions to meet the specific performance requirements of different workloads, even if they’re running on different platforms. Mainframe users can fine-tune the DS8300 array even more with support for Parallel Access Volumes (PAV) technology, which allows for instant snapshots of frequently accessed data to serve applications requesting those data sets in parallel, thereby eliminating disk contention.
It is not surprising that IBM, which has struggled for respect in the high-end storage array business, is trying to make the most out of this announcement. It says that, for the equivalent amount of storage, the DS6000 costs about half, and is one-twentieth the size, of EMC’s DMX800 storage array. “These are the most significant storage announcements we have made in more than a decade,” said Dan Colby, general manager of IBM’s storage systems division.
The DS6000 will start at $97,000 in a base configuration, while the DS8300 will cost up to $4 million for a large configuration. IBM is including four-year warranties with both of these machines, which will be available on a limited basis in December. Full availability of the DS6000 and DS8000 machines is expected in the first quarter of 2005.