Power10 Boosts NVM-Express Flash Performance

June 5, 2023 Timothy Prickett Morgan

We are always on the lookout for any performance tests that show the benefits of adding flash storage to Power Systems iron, and we found some recently in an NVM-Express flash drive deep drive given by Douglas Gibb’s the I/O product manager for the Power Systems line at IBM during the POWERUp 2023 conference in Denver.

The presentation that Gibbs gave went through all of the ins and outs of flash storage on Power Systems, including those that use the NVM-Express protocol over the PCI-Express peripheral bus, which offers a direct link between the operating system and the flash storage rather than having flash storage emulate a SAS or SATA drive as happened before the NVM-Express native flash protocol was invented.

As you know, the Power10 servers, top to bottom, only support NVM-Express flash drives as internal storage, and as part of the April 12 announcements, Big Blue also rolled out a new NVM-Express Expansion Drawer, product NED24 and known also by feature #ESRO, to allow for a whole lot more NVM-Express drives to be attached to a particular Power10 server. The NED24 chassis is not supported on Power9 or earlier machines; it is supported on Power10 iron running the IBM i, AIX, or Linux operating systems. The NED24 drawer is supported natively on IBM i 7.4 and IBM i 7.5, which means customers do not have to use the Virtual I/O Server (VIOS) to link to external NVM-Express flash. (This NED24 support comes through IBM i 7.4 with Technology Refresh 8 and on IBM i 7.5 with Technology Refresh 2.)

The last time we gout our hands on some flash performance data was way back in November 2020, and that chart was almost a year old when we finally got our hands on it and shared it with you. That particular data compared SAS drives to NVM-Express drives on Power9 iron, with the disks being protected with RAID 5 striping or RAID 10 mirroring (a mirrored pair of RAID 5 controllers) compared to the flash drives being mirrored by the operating system and using CPU cores as the mirror controller. IBM highly recommends mirroring of any NVM-Express flash drive on a Power Systems machines – it is really required and rightfully so – by IBM. Sometimes, this mirroring makes NVM-Express drives run a little bit slower than SAS, but in general, flash offered substantially better performance than SAS drives.

At the time of POWERUp 2023, Gibbs had just got his hands on this performance data below the day before and shared it immediately with the attendees at the event who came to his presentation. Take a look:

This one compares the read and write performance for sequential and random data access for Power10 machines versus Power9 machines, and as Gibbs pointed out, the Power10 chip has a more efficient NVM-Express driver so the cores are hit less hard doing the flash drive mirroring. And the Power10 chips are more powerful I/O devices and computing devices in their own right, which we think is helping drive flash drive performance improvements generation to generation. In fact, we suspect with tuning and a new generation of even faster NVM-Express devices, IBM can widen the gap quite a bit more than this between Power10 and Power9.

“This would be a great chart if the Power9 had SSDs only because most of the upgrades we’re doing are from Power9 SSDs to Power10 NVM-Express,” Gibbs admitted.

These tests were likely run, he added, on a Power S1022 or Power S1024 versus a Power S922 or Power S924, and very likely for machines with only four drives. The Power10 machine has more NVM-Express flash slots than this, and now has the NED24 expansion drawer, too, so it can, in theory, offer a hell of a lot more I/O units, capacity, and throughput in a Power10 setup.

Note: That 4 KB random read jump of 4.3X moving from Power9 to Power10 is perplexing, and Gibbs is looking into it.

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