Original URL: http://www.theregister.co.uk/2012/02/10/ibm_exflash/

IBM: We do server flash already...

We just didn't tell many people about it

By Chris Mellor

Posted in Servers, 10th February 2012 18:42 GMT

With all this EMC Lightning kerfuffle and Dell, HDS and NetApp joining in – with HP pointedly saying "No comment" like we really believe it's not playing too – there's a Big Blue elephant we're not hearing or seeing. Don't worry, IBM definitely has skin in this game – and it's called eXFlash.

This is solid state storage local to its xSeries servers, and it was introduced back in March 2010 with the then-new eX5 servers. In its release at the time IBM said: "eXFlash – a unique, next-generation flash-storage technology – replaces an older, less reliable generation of storage and can slash storage costs up to 97 per cent by replacing hundreds of hard-disk drives and thousands of wires and cables... Each eXFlash replaces 80 JBODs, each of which includes multiple disks and other components that all require cabling."

A December 2011 Redbook abstract talked of a refreshed eXFlash offering:

Compared to the previous generation, the new features of the IBM eXFlash solution include:
  • Hot-swap capability
  • IOPS performance improved by six times to 240,000 IOPS per eXFlash unit
  • Storage capacity increased by four times to 1.6 TB per eXFlash unit

    You can expect further expansion of IBM eXFlash capabilities for both IOPS and throughput performance and capacity over time as SSD technology improvements are developed and adopted by the industry.

The Redbook (PDF) itself provides fulsome eXFlash information.

The book says: "Currently, the processor, memory, and I/O subsystem are well balanced and virtually not considered as performance bottlenecks in the majority of systems. The main source of performance issues tends to be related to storage I/O activity because the speed of traditional HDD-based storage systems still does not match the processing capabilities of the servers."

It goes on to say:"Despite an increase in rotational speed of disk plates and higher density of stored data, the response time of HDD is still several milliseconds, which effectively limits its maximum IOPS. For example, a single 2.5 in.15K rpm SAS HDD is capable of approximately 300 IOPS.

"With SSD-based eXFlash latency is measured in dozens of microseconds (or almost 100 times lower latency than for hard drives), which in turn leads to the 240,000 IOPS capabilities identified earlier. Higher IOPS capabilities also mean higher queue depth and therefore better response time for almost all types of storage I/O-intensive applications.

"In other words, if the application is multi-user, heavily loaded, and accesses storage with random I/O requests of a small size, then this application is a good candidate to consider to put its entire data set (or part of it) on an IBM eXFlash or external SSD-based storage system."

The eXFLash box is an internal storage box for servers using up to eight hot-swap SSDS connected to one or two controllers which can provide RAID functionality. Each eXFlash unit takes up four2.5-inch drive bays.

IBM eXFlash box (IBM)

IBM eXFlash unit

There are front-accessible, 1.8-inch SSDS inside the eXFlash box's bays, and the box offers up to 1.6TB of capacity using 200GB eMLC SSDs, up to 240,000 random read IOPS, and up to 2GB/sec sustained read throughput.

IBM says: "eXFlash is optimized for a heavy mix of random read and write operations, such as transaction processing, data mining, business intelligence and decision support, and other random I/O-intensive applications."

Read the Redbook for more information. In summary: IBM has a VFCache equivalent and has had for over a year. ®