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Update to VxRail 7.0.100 and Unleash the Performance Within It

Thu, 05 Nov 2020 23:07:52 -0000

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David Glynn

What could be better than faster storage? How about faster storage, more capacity, and better durability?

Last week at Dell Technologies we released VxRail 7.0.100. This release brings support for the latest versions of VMware vSphere and vSAN 7.0 Update 1. Typically, in an update release we will see a new feature or two, but VMware out did themselves and crammed not only a load of new or significantly enhanced features into this update, but also some game changing performance enhancements. As my peers at VMware already did a fantastic job of explain these features, I won’t even attempt to replicate their work – you can find links to the blogs on features that caught my attention in the reference section below. Rather, I want to draw attention to the performance gains, and ask the question: Could RAID5 with compression only be the new normal?

Don’t worry, I can already hear the cries of “Max performance needs RAID1, RAID5 has IO amplification and parity overhead, data reduction services have drawbacks”, but bear with me a little. Also, I’m not suggesting that RAID5 compression only be used for all workloads, there are some workloads that are definitely unsuitable – streams of compressed video come to mind. Rather I’m merely suggesting that after our customers go through the painless process of updating their cluster to VxRail 7.0.100 from one of our 36 previous releases in over the past two years (yes you can leap straight from 4.5.211 to 7.0.100 in a single update and yes we do handle the converging and decommissioning of the Platform Services Controller), that they check out the reduction in storage IO latency that their existing workload is putting on their VxRail cluster, and investigate what it represents – in short, more storage performance headroom.

As customers buy VxRail clusters to support production workloads, they can’t exactly load it up with a variety of benchmark workload test to see how far they can push it. But at VxRail we are fortune to have our own dedicated performance team, who have enough VxRail nodes to run a mid-sized enterprise, and access to a large library of components so that they can replicate almost any VxRail configuration we sell (and a few we don’t). So, there is data behind my outrageous suggestion, it isn’t just back of the napkin mathematics. Grab a copy of the performance team’s recent findings in their whitepaper: Harnessing the performance of Dell EMC VxRail 7.0.100: A lab based performance analysis of VxRail, and skip to figure 3. There you’ll find some very telling before and after performance latency curves with and without data reduction services for an RDBMS workload. Spoiler: 58% more peak IOPS and almost 40% lower latency, with compression this only drops to a still very significant 45% more peak IOPS with 30% lower latency. (For those of you screaming “but failure domains” check out the blog Space Efficiency Using the New “Compression only” Option where Pete Kohler explains the issue, and how it not longer exists with compression only.) But what about RAID5? Skip up to figure 1 which summarizes the across the board performance gains for IOPS and throughput, impressive, right? Now slide down to figure 2 to compare the throughput, in particular compare RAID 1 on 7.0 with RAID 5 on 7.0 U1 – the read performance is almost identical, while the gap in write performance has narrowed. Write performance on RAID5 will likely always lag RAID1 due to IO amplification, but VMware is clearly looking to narrow that gap as much as possible.

If nothing else the whitepaper should tell you that a simple hassle-free upgrade to VxRail 7.0.100 will unlock additional performance headroom on your vSAN cluster without any additional costs, and that the tradeoffs associated with RAID5 and data reduction services (compression only) are greatly reduced. There are opportunistic space savings to be had from compression only, but they require committing to a cluster wide change to unlock, which is something that should not be taken lightly. However, realizing the guaranteed 33% capacity savings of RAID5, can be unlocked per virtual machine, reverted just as easily, represents a lower risk. I opened asking the question if RAID5 with compression only could be the new normal, and I firmly believe that the data indicates that this is a viable option for many more workloads.

References:

My peers at VMware (John Nicholson, Pete Flecha (these two are the voices and brains behind the vSpeakingPodcast – definitely worth listening to), Teodora Todorova Hristov, Pete Koehler and Cedric Rajendran) have written great and in-depth blogs about these features that caught my attention:

vSAN HCI Mesh – eliminate stranded storage by enabling VMs registered to cluster A access storage from cluster B

Shared Witness for 2-Node Deployments - reduced administration time and infrastructure costs thru one witness for up to sixty-four 2-node clusters

Enhanced vSAN File Services – adds SMB v2.1 and v3 for Windows and Mac clients. Add Kerberos authentication for existing NFS v4.1

Space Efficiency: Compression only option - For demanding workloads that cannot take advantage of deduplication. Compression only has higher throughput, lower latency, and significantly reduced impact on write performance compared to deduplication and compression. Compression only has a reduced failure domain and 7x faster data rebuild rates.

Spare Capacity Management – Slack space guidance of 25% has been replaced with a calculated Operational Reserve the requires less space, and decreases with scale. Additional option to enable Host rebuild reserve, VxRail Sizing Tool reserves this by default when sizing configurations, with the filter Add HA

Enhanced Durability during Maintenance Mode – data being intended for a host in maintenance mode is temporally recorded in a delta file on another host, providing the configured FTT during Maintenance Mode operations

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Update to VxRail 7.0.100 and Unleash the Performance Within It

What could be better than faster storage? How about faster storage, more capacity, and better durability?

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