Does Flash make everything in VMware Better?

Bacon makes everything taste better – at least for a lot of folks. At VMworld we met up with Micron, the flash manufacturers who are calling themselves “VMware’s bacon”. Their point is that flash makes everything in a virtual server and VDI world better. When we asked Micron to explain this to us, they brought up VSAN, an appropriate example for VMworld.

The VSAN reference model for storage says to use a PCIe card in the host server for acceleration and a hard disk drive for storage. Well, as most users have found out, applications that are supposed to use flash end up running on hard drive storage, at one time or another. This can create havoc with production applications that are expecting flash performance. So Micron asked “What if we could replace that HDD with an SSD, wouldn’t that resolve the issue?” It might, but would that be cost effective? Here’s what we found out.

According to Micron, enterprise-grade 10K RPM hard drives cost ~$0.58 per GB (~$700 for 1.2TB SAS) and a Micron 960GB SATA SSD costs about $0.54 per GB (~$500 for a 960 GB SSD). But what about endurance, flash wears out, right?

As it turns out, an enterprise HDD in a real world environment writes a lot less data than many people think. Using a random write speed of 400 IOPS * 4KB block size * 30% writes (70/30 read/write mix) * 31.6 million seconds means a hard drive will only write about 15 TB in a year’s time or 75TB in a typical 5 year lifespan.

A read-centric SSD, like the 960GB SATA SSD above that’s warrantied for a five-year life span, will sustain as much data as the HDD. If needed, an enterprise version of the drive can provide 1-3 fills per day, more than 20x the 75TB shown in the HDD example.

But here’s the difference, the SSD can give you 48,000 IOPS or more, compared to ~400 IOPS for the HDD. This means that while the cost is about the same for these two drives and they both can support a 5 year lifespan, the SSD can give you over 100x the amount of performance.

In a VMware environment, where storage performance is typically the gating factor, this can greatly increase your VM density. In fact, Micron recently ran a test where they replaced the hard drives in three VMwWare hosts with SSDs and successfully ran over 1000 VMs on a single server – more details in this video.

So in a VSAN implementation, replacing the hard drive with an SSD can pay big dividends. While bacon may improve the taste food, putting in flash really does make VMware better.

This Video is Sponsored by Micron

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