Power Systems Get Some I/O and Storage Enhancements

April 25, 2011 Timothy Prickett Morgan

A fair argument can be made that innovation is progressing faster and is much more keenly needed in the storage arena than in processors and other elements of a system–with the possible exception of main memory technology, which is woefully lagging processor and flash/disk storage innovation. As part of the Power Systems blade and midrange systems update two weeks ago, IBM rolled out a bunch of subtle enhancements to the storage it sells with the Power-based server line.

Disk drives have not been replaced completely by flash memory, and given the relatively low cost of storage capacity, they won’t be for a long time. Cheaper disks have made it possible to affordably keep some data in a nearline state on disk arrays with relatively slow and fat disks, and the advent of flash-based solid state drive (SSDs) with very high I/O capacity has allowed for very hot data to be moved off disks and put on flash. Any modern system had to be able to use main memory, flash memory, disk drives, and tape drives in a hierarchical fashion, and as transparently as possible.

But before this can happen in the systems software, you have to have a box that can hold all of these modern devices in a compact manner. Enter the new EXP24S generation two drawer from IBM. This 2U rack-mounted I/O drawer, which is detailed in announcement letter 111-065 and which is known by the catchy name feature 5887 in the Power Systems lineup, has room for 24 hot-swap 2.5-inch disks or SSDs. The drawers link back to SAS controllers in the Power Systems boxes by SAS X or Y cables. (If you have an X and a Y cable, does that make it a male system, and does two X cables make it female? I am just saying. . . .)

This feature 5887 drawer is a SAS Gen-2 box that cannot use the 2.5-inch SAS Gen-1 storage devices that plug into the media bays of the Power7-based servers or the 12X PCI-Express I/O drawers (features 5802 and 5803. The Gen-2 SAS devices support data transfer speeds of 6 Gb/sec, compared to 3 Gb/sec for the Gen-1 devices; hence, IBM makes them not interchangeable on purpose to keep you from mixing drives and devices of different speeds on the same controller. That said, IBM is supporting a number of 3 Gb/sec SAS controllers with the EXP24S drawer.

The Power 520 and Power 550 servers have Gen-2 SAS controller embedding on their motherboards, with SAS Gen-2 ports coming out of the back of the system. The entry, midrange, and enterprise systems in the Power7 lineup–that is the Power 710, 720, 730, 740, 750, 770, and 780, as well as the Power 755 supercomputer node–also have SAS adapters and controllers that can be used to link to the new EXP24S Gen-2 I/O drawer, including the PCI-X 1.5 GB cache SAS RAID adapter (features 5904, 5906, and 5908), the PCI-Express 380 MB SAS RAID adapter (features 5805 and 5903), and the PCI-Express dual x4 SAS adapter (features 5901 and 5278). Those three different sets of controllers all work on machines running AIX or Linux or using the Virtual I/O Server (VIOS) to link to peripherals, but the latter one does not support the EXP24S on the latter pair of features. You can order the EXP24S as a single bay with 24 devices, or have IBM carve it up into two sets of 12-bay devices or four sets of six-bay devices.

The feature 5887 EXP24S I/O drawer costs $5,400. IBM is offering 2.5-inch disk drives for the units in 10K RPM in 283 GB/300 GB capacities (the former is formatted for IBM i and the latter for AIX, Linux, and VIOS) and 15K RPM speeds in 139 GB/146 GB capacities. IBM is also launched a new 571 GB/600 GB that spins at 10K RPM (features 1790 and 1916 running IBM i and features 1962 and 1964 running AIX and Linux); these disks cost $1,200 each. The prices on the smaller disks match the price cuts Big Blue announced separately and that we covered in last week’s issue of The Four Hundred.

IBM is also rolling out a new 177 GB enterprise multi-level cell (eMLC) flash drive in a SAS package that can be plugged into first-generation SAS bays or I/O drawers as well as the feature 5803 12X PCI-Express I/O drawer for the Power 795 server. This drive is known as feature 1775 or 1787, depending on the machine it plugs into, and it costs $4,700.

The Power 795 is also getting a 1U, rack-mounted I/O drawer for supporting half-height DAT 160 or LTO 5 tape drive or slimline DVDs. This feature 5724 drawer costs $4,200.

IBM is also allowing for the feature 5638 LTO 5 tape drive, with 1.5 TB uncompressed capacity, that is used in the Power 720 and 740 servers already to be used in the Power 750 or the new I/O unit for the Power 795 mentioned above. This tape drive costs $4,000.

Not that this matters much for IBM i and OS/400 shops, but IBM has also announced a PCI-Express 2.0, low-profile adapter that provides two quad data rate InfiniBand adapters for Power 720 and 740 machines. If you don’t have the required PCI-Express slots to use this adapter in you machine and you want fast InfiniBand, IBM says stick with the 12X bus-to-QDR InfiniBand adapters is has been peddling. (The problem with this is that the 12X adapter in the GX slot on the Power Systems machines only runs at the double data rate (20 Gb/sec) speed.) IBM also warns that there are bandwidth issues with the new feature 5283 adapter, which costs $1,000, in that the PCI-Express slot can only handle half the bandwidth of two 40 Gb/sec QDR InfiniBand ports anywhere. So you are going to be stuck at DDR InfiniBand one way or the other, it is just that the new way gives you twice as many ports per system.

All of these disk, SSD, and I/O enhancements will be ready for purchase on May 20.

In a forward-looking statement, IBM said that it plans to put out a SAS-based PCI-Express controller in the third quarter of this year that attached to modern Power Systems that will be aimed at “clients with large numbers of HDDs or SSDs per adapter.” This future SAS adapter will plug into Power 720, 740, 770, 780, and 795 systems and into Power 750s and earlier generations of Power6-based servers using 12X PCI-Express I/O drawers. Initially, this fatter SAS controller will support AIX 5.3, 6.1, and 7.1 as well as IBM i 6.1 using VIOS to link to peripherals and i 7.1 with or without VIOS. The plan calls for IBM to link to VIOS-less IBM i 6.1 machines in the fourth quarter. This adapter will be configured as pairs of single-width PCI-Express cards, as Big Blue has done in the past.