SanDisk Announces FlashSoft 4.0 for vSphere 6

SanDisk recently announced their next generation of FlashSoft software for vSphere. I was fortunate enough to receive a briefing from Rich Petersen and thought I’d share a few thoughts.

Firstly, you can check out FlashSoft 4 for vSphere 6 here. Here’s a post from Rich on the subject too. While you may be familiar with SanDisk via flash cards and USB sticks, they’ve also been doing a fair bit with host-side caching software in recent years.
There’re a few reasons you might choose to use host-side caching via SSDs in your host:

  • Improved VM density
  • It’s an easy way to add improved performance without necessarily upgrading your SAN

Some of the benefits of FlashSoft include

  • IO removed from the SAN (out of the kernel)
  • Write-back caching


Last VMworld, VMware announced vSphere APIs for IO filtering (VAIO). Chris has a nice write-up on it here.

  • Uses “IO Filters” for integrating storage services
  • Caching and Replication first, others coming in the future
  • VMware Storage Policy-Based Management (SPBM)
  • Services are installed, managed and maintained as “native components”
  • vCenter is “control point” for SDS with 3rd-party storage services
  • Data services for storage functions running at the host level
  • Third Party Solutions can be certified VMware Ready




FlashSoft 4.0

SanDisk are positioning this release of FlashSoft as a successor to vFRC (a product that I think highly of but haven’t seen much in the field). So what does this release offer?

  • Write-back as well as write-through
  • VMware-native data service
  • Installed, managed, maintained by vCenter
  • Integrated through SPBM (storage policy-based management)
  • Certified VMware ready

Some of the benefits of this release include performance, stability, ease of administration, versatility and resilience.
SanDisk pointed out that, while vFRC will be still be supported, it is limited in the sense that cache resources were allocated on a per-VM basis (static not dynamic), and it was only available in the Enterprise Plus edition. Note that FlashSoft is supported in all vSphere versions except Essentials, as it does not support VAIO.

Interestingly, FlashSoft uses the vMotion network to share data between cache pairs, and uses the same mechanism to provision SSDs (VFFS) as you did with vFRC.


Here’s how cache writes work with the write-back caching:

  1. Cache write hit from VM in server A
  2. Data replication to SSD on Server B begins
  3. Data is copied to replication space on SSD in server B
  4. Data is concurrently recorded on cache in server A
  5. Write acknowledged from server B
  6. Write acknowledged to VM in server A

So how do you buy it? SanDisk currently have agreements in place with Dell, Lenovo, HP and HDS for FlashSoft to be bought with a server. The VAIO APIs are in tech preview with the general availability projected for vSphere 6 U1. From a roadmap perspective, FlashSoft 4.0 will be the caching software for offered by SanDisk moving forward, offering existing IO-turbine customers the ability to upgrade.


Final Thoughts

I like the concept host-side caching a lot. I think it’s a clever way to leverage occasionally stretched resources without having to go the monolithic storage upgrade route. SanDisk are understandably excited about this announcement, particularly with the tight integration with vSphere 6. It certainly looks good on paper, and I’m looking forward to getting some stick time with the product when it’s available.