IBM Debuts Baby 'Shark' Array for Unix Servers

by Alex Woodie

Companies that have looked for a storage area network (SAN) disk array but were turned off by the high price of IBM's Enterprise Storage System (ESS) Model 800 "Shark" array now have another option from Big Blue. Last week the company launched the ESS Model 750, a scaled-down Shark array that features fewer processors, disk drives, and bus adapters than the Shark 800, but starts at only $150,000 for 1.1 TB of storage.

The baby Shark 750 is based on the same architecture as the ESS Model 800, and includes much of the same replication and disaster recovery software as its older Shark brothers, including Peer to Peer Remote Copy (PPRC V2), FlashCopy V1 and V2, and RAID 5 and RAID 10 striping. You will also find support for mainframe-centric data management capabilities, such as priority I/O queuing and multiple allegiance, in the new Model 750, as well as older models.

While the software stacks of the Shark 750 and Shark 800 are quite similar, when it comes to the hardware, there is simply less of it with the Shark 750. For example, the Shark 750, which is based on the pSeries Model 630 server, features only a two-way Power4 processor (as opposed to the four- or six-way Model 800) and only 8 GB cache memory (compared to the maximum of 64 GB main memory in the Model 800).

In terms of I/O and storage, the Shark 750 aims to get the job done with six 2 Gbps Fibre Channel/FICON or ESCON host adapters (through one FC/FICON port or two ESCON ports). The Shark 800, on the other hand, is capable of much more throughput, with up to 16 Fibre Channel/FICON ports or up to 32 SCSI/ESCON ports, supporting many more actual adapters.

In terms of disk drives, the Shark 750 will hold up to 64 disk drives (with eight of IBM's eight-drive packs), using 72.8 GB or 145.6 GB 10K RPM drives for a maximum of 4.6TB of storage. The Shark 800, on the other hand, holds up to 384 10K RPM or 15K RPM drives of varying (and mixed) capacities, giving it a maximum total capacity of nearly 56 TB when configured with the largest eight-packs of 145.6 GB drives.

You cannot load 15K RPM disks into the Shark 750. The reliance on 10K RPM disks is one of the reasons why IBM recommends the Shark 750 for workload densities that average about two operations per second per gigabyte of storage, or less. If you're making more disk calls than that, buy the bigger Shark. Overall, IBM advises customers that if they plan on needing more than 4 TB of storage capacity within three years of purchasing the Shark 750, then they should consider the Shark 800 instead. The Shark 750 shares the same architecture as the Shark 800 and is field upgradeable to the full Shark array with a minimum of disruption, IBM says. This stands to reason, since they are really just AIX servers with special microcode that makes them disk arrays. IBM could make a Shark 10000 out of a 32-way pSeries 690 if it wanted to.

In addition to linking to IBM AIX, HP-UX, and Solaris Unix servers, the Shark 750 will connect to IBM's zSeries mainframes, the iSeries Power-based midrange servers, and Windows servers from myriad vendors. The Shark 750 features a new release of the Shark operating environment, ESS LIC level 2.3.1. The Shark 750 ships on May 28, 2004.