XIV Clustered Disk Arrays Get More Oomph And Capacity
July 26, 2011 Timothy Prickett Morgan
IBM has kicked out the third generation of its XIV clustered disk arrays, high-end machines for delivering lots of bandwidth and high-end software features such as thin provisioning, snapshotting, asynchronous and synchronous mirroring, and hot upgrades of cluster components.
Big Blue bought disk array upstart XIV back in January 2008 so it would have a clustered disk array that was more expandable and more resilient than the monolithic DS8000 series of high-end disk arrays, which are based on Power Systems servers. The XIV machines are based on Intel Xeon processors running Linux, with main memory serving as cache for disks. Multiple nodes are linked together using fast InfiniBand adapters and switches from Mellanox Technologies, and the disk array software running on the cluster makes it look like any block-level disk array to the operating systems that attach to it. In fact, the machine links to server through normal Fibre Channel or iSCSI links. IBM has more than 1,100 customers with more than 4,500 different XIV clusters installed.
In July 2009, IBM added support for the OS/400 and i operating system on the XIV arrays, so customers with IBM i can make use of the cool features in the XIVs to add many terabytes of storage to their arrays while doing interesting things like take a nearly instantaneous snapshot of a running IBM i image so it can be backed up for high availability or pushed off to tape (or both). (check out this Redbook on XIV copy services and migration for more details on how IBM i can make use of the XIV arrays.)
The XIV Generation 3 arrays are based on SAS disks with 2 TB of capacity, an improvement in terms of reliability over the 1 TB and 2 TB disks used in the Generation 2 arrays. The Generation 3 arrays have from 6 to 15 modules, which is where the array compute and cache are stored. With the XIV Generation 3 machines, each module has four Xeon cores with HyperThreading turned on, for a maximum of 120 virtual cores; each module has 24GB of main memory that functions as read/write cache. The Generation 2 arrays topped out at 84 physical cores and offered either 8GB or 16GB of memory for cache. Both families supported from 72 to 180 disk drives and 24 Fibre Channel ports. (The Gen 3 boxes use 8Gb/sec Fibre Channel, while the Gen 2 boxes used 4Gb/sec Fibre Channel.) The new machine has up to 22 iSCSI links, compared to six for the earlier machine, and has double the bandwidth, at 480Gb/sec, moving data from cache to disk drives. After mirroring of data, the XIV Generation 3 array offers from 55 TB to 161 TB of usable capacity.
In a statement of direction, IBM said that the VIX Generation 3 arrays would be given a solid state disk (SSD) caching option sometime in the first half of 2012 that would put up to 7.5 TB of flash-based read cache onto the array nodes and would reduce random read latencies by as much as 90 percent.
The base price of the XIV 2810 Model 114 array is $135,700, while the VIX 2812 Model 114 costs $183,195. The latter machine comes with a three-year warranty instead of a one-year warranty, and that is the only difference between the two. Presumably, that price is for the base configuration of the XIV array, which has six nodes, three interface modules (feature 1125) with eight Fibre Channel ports running at 8Gb/sec and six iSCSI ports running at Gigabit Ethernet speed, and three data modules (feature 1126) with 72 disk drives. Each interface or data module has a dozen 2TB drives on it and costs $90,750, but only one of those disks is activated. You have to pay $9,075 to activate each disk. That’s $190,575 per drawer, and the XIV array tops out at 15 drawers total or an additional 9 more above the base configuration, which works out to $1.9 million for a fully loaded box with three years of maintenance, or $11,791 per usable terabyte.
That’s just for the hardware. If you want the software that actually turns this from an InfiniBand-Xeon cluster into a funky disk array, then the new XIV Software V11.0 (product number 5639-YYB) costs $41,800 per module plus $16,720 per module for three years of maintenance. So you need another $877,800 to buy the software for the new XIV arrays. If you take the three-year price for the hardware and software and add them together, you get $2.78 million, or $17,243 per usable terabyte.
The XIV Generation 3 array will be available on September 8.
In addition to launching the Generation 3 XIV clustered arrays, IBM also cut the price of the older Generation 2 products in announcement letter 311-091. The base six-module XIV Generation 2 machine is now $103,840, down 12 percent from its previous $118,000. The machine with a three-year warranty costs $140.184, down 12 percent as well. Prices for data and interface modules as well as disk activations were also all reduced by 12 percent.
Correction: This story originally said that IBM was charging for the XIV software based on each 2 terabyte disk that was activated on the system, which was a crazy amount of money. IBM charges by the module for the software, not by the capacity activated. IT Jungle regrets the error.