VMware and SanDisk boost caching with vsphere VAIO API

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1 REPORT REPRINT VMware and SanDisk boost caching with vsphere VAIO API TIM STAMMERS 24 SEP, 2015 Server-side caching software has not set the storage market alight, despite its apparent virtues. Enter an API call VAIO, developed by VMware with flash giant SanDisk as a design partner. The duo says that VAIO will cause a night and day transformation. SECTORS ALL / STORAGE / OTHER Research, LLC

2 Server-side flash caching software appears to promise much, but the overall sector has seen sluggish growth. One likely factor behind this is lack of customer confidence in the technology. Another more certain issue is that there have been varying levels of functionality when such software is used with VMware s widely deployed vsphere platform. This situation is set to change with the release of an API called vsphere APIs for IO Filtering (VAIO). VMware and SanDisk say the API will allow third-party caching software products to become first-class vsphere citizens. VAIO-enabled caching products will receive the top-level VMware Ready technical support certification, and will be managed and installed with full vsphere policy-based automation. VAIO will also make it easier for third parties to deliver better fundamental caching functionality when running in vsphere. The API came out of technical preview this month, when vsphere 6.0 update one (U1) was released. SanDisk was VMware s design partner for VAIO with respect to the filter for third-party caching software, but VMware expects other caching vendors to ship VAIO-enabled products before the end of Q THE 451 TAKE The VAIO API looks set to provide a significant boost to the generally moribund caching sector, although the full impact will not happen overnight, and the API appears unfinished in at least one area, namely snapshot integration. VAIO continues VMware s long-running efforts to make vsphere work better with third-party products, including the storage arena, and hence boost the appeal of the VMware platform. Previous examples include the VASA storage API and the vsphere VVOLS feature released earlier this year. VAIO is also linked to VMware s failure to create its own competitive server-side caching product and can be seen as an effort to allow other suppliers to plug that gap more effectively. CACHING BACKGROUND Flash usage in the datacenter is accelerating rapidly. The most common form of datacenter flash use is within hybrid disk-and-flash arrays, and the fastest-growing is within all-flash arrays. A third way to use flash is inside servers, under the control of server-side caching software. This method of using flash promises to deliver extremely high performance for mainstream applications with low capital outlay and no change or disruption to back-end storage systems. It does this by creating cache copies of hot or frequently demanded data and storing those caches in flash drives within servers. Because the drives are inside the servers that need to access the data, the performance boost is potentially much greater than if data is stored in flash in arrays, on the other side of latency-inducing storage networks. As a result, server-side caching has attracted multiple vendors. But with the notable exception of startup PernixData, which claims soaring sales, we are unaware of any suppliers that have declared sales numbers or reported real market traction. One likely factor is lack of customer trust in the concept of caching in general. In a 2014 survey of more than 200 enterprise storage chiefs completed by 451 Research s InfoPro service (now the VotE service), 56% of respondents said the ability of flash-caching systems to maintain data integrity as an extremely or very important issue. SanDisk itself says that when it has told customers about VAIO, their most common response has been that VMware Ready certification will be the most important benefit. Another drawback is the varying levels of interoperability with key vsphere functions such as vmotion and Distributed Resource Scheduler (DRS). Given the popularity of vsphere virtualization and those functions in enterprise datacenters, this has been a major issue. THE BASICS OF VAIO VMware unveiled VAIO in 2014, and this year described the API as giving the highest possible level of integration between vsphere and third-party software services. VAIO-enabled software will be managed by vsphere as if it were a feature of vsphere itself. VSphere vcenter will automate the installation of such software across multiple host servers within a cluster, replacing the current manual, server-by-server installation of third-party products. After the installation, vsphere s Storage Policy Based Management (SPBM) feature will maintain policies to manage data services delivered by third-party software in the same way it does for native VMware services.

3 Policies for VAIO-enabled, third-party software services will be listed in the SPBM registry alongside VMware services. In addition, VMware says the API allows third-party products with direct but safe access to IO traffic. VAIO allows third-party software to create filters that intercept the IOs between VMs and their virtual disks, transparently to the VMs. Initially, VAIO will support caching and replication services, but VMware plans to extend VAIO usage into areas such as security, antivirus protection and encryption. VMWARE VFLASH, FRC AND NOW VAIO VMware itself entered the caching market in 2013 when it launched a product called VMware Flash Read Cache (FRC) software. However, VMware has described FRC as a basic product that gives customers a taste of what can be achieved with the technology in general. The biggest weakness of FRC is that it requires manual reconfiguration of the amount of flash allocated to individual VMs when loads change, or when VMs move from one host to another. FRC was the outcome of an earlier, failed effort by VMware to create a vsphere caching API. That effort was called vflash, and VMware said it ran aground because of conflicting third-party requirements. This presumably is why for VAIO, VMware chose only one caching design partner. SanDisk is one of several vendors selling server-side caching software, and it says it was chosen by VMware for the design role because of its technical competence and integrity. CERTIFICATIONS Currently, the highest level of certification for all third-party caching products is as a VMware Partner Verified and Supported Product (PVSP). In contrast, VAIO-enabled caching products will be candidates for the top-level VMware Ready certification. When a customer using a PSVP-certified caching product requires VMware technical support, VMware s declared formal process requires the customer to prove that the caching software is not causing the problem by replicating the problem on another setup not running that software. This is not a trivial requirement, and it is especially painful if the technical problem needs rapid attention because it is affecting application service levels. VMware Ready certification does not carry that limitation. If there is a problem, the customer does not need to demonstrate that the third party is not causing the problem. This is linked to VMware s statements that VAIO protects the ESX kernel from badly behaved third-party software. Current caching products use VMware s Pluggable Storage Architecture (PSA) to access the kernel, and VMware has said that some of these offerings are Frankenstein s monsters that use PSA for more than it was designed. VAIO filters run in the VM user space so that if a VM fails, the ESXi hypervisor and the other VMs it is hosting are not affected. VMware has made it clear that for caching, PSA is now history at least as far as VMware is concerned. It has said unequivocally that if caching vendors do not adopt VAIO, they will receive no certification at all neither PVSP nor VMware Ready for vsphere 6.0 or any future vsphere versions. Existing PVSP certifications for earlier versions of vsphere will remain, but there will be no further certification of any type for non-vaio products. SIMPLER WRITE CACHING Many caching products only cache reads and do not cache writes. In other words, they accelerate read operations but do not directly accelerate write operations. However, write caching is desirable for certain write-heavy applications, such as transactional and analytics databases. But write caching (also known as write-back caching) introduces complications in keeping the cache data synchronized or coherent with the master copy of data held in back-end storage systems. It also introduces complications when used for VMs that are moved from one physical host to another by VMware functions such as HA and vmotion. At a detail level, when a back-end storage system creates an array-based snapshot for disaster recovery, it needs to be aware that data is also being held in a server-side write cache; otherwise, the contents of the snapshot will be invalid. This means the cache must coordinate with back-end arrays, via scripts, to ensure that all writes are copied from the cache to the back-end storage or are flushed before a snapshot is created. Caching vendors have consistently said that this integration is trivial. However, SanDisk and VMware have highlighted the fact that VAIO eliminates the need for it by automatically telling an IO filter to flush a cache when a snapshot is being taken provided the snapshot is being made by vsphere itself. VAIO at present does not address the coordination needed when the snapshots are array-based. Because array-based snapshots are more widely used than vsphere snapshots, SanDisk says that it and VMware may update VAIO to take care of this issue.

4 SanDisk says VAIO also simplifies data coherency when write caching is used with VMware virtualized servers. Indeed, SanDisk s FlashSoft software was originally written to use the PSA interface, and although it previously supported write caching for physical servers, it did not do so for virtualized servers. The new VAIO-enabled version of FlashSoft allows write caching for VMs. SanDisk s updated caching product SanDisk Flashsoft 4.0 for vsphere 6.0 will ship before the end of the year with all of the features mentioned above, including VMware Ready certification, full integration with vsphere SPBM, and support for write caching with VMware HA, vmotion and DRS functions. VMware s FRC caching software When we asked VMware about the future of its own FRC caching software, it said FRC continues to be a part of vsphere 6.0. VMware added that its Virtual SAN software is an alternative way to use server-side flash. We think this is a reminder that among all of VMware s storage efforts, Virtual SAN is the biggest and has the most potential to impact the storage market. VMware has already made clear its strong ambitions for Virtual SAN. It is important to note that Virtual SAN is in a very different product category than FRC or any other caching software. Virtual SAN is a full storage system and an alternative to conventional back-end SAN and NAS storage. Caching software is a non-disruptive complement to conventional back-end storage. COMPETITION The major rivals to VMware vsphere are Microsoft Hyper-V-based virtualization and KVM-based Red Hat Enterprise Linux virtualization. Because those two platforms have smaller market shares than vsphere, they are currently much less widely supported by third-party server-side caching products. A notable exception is SanDisk FlashSoft version 3.7, which supports Hyper-V and Hyper-V functions such as LiveMigration. But FlashSoft 3.7 only provides that full Hyper-V support for read caching unlike FlashSoft 4.0 for vsphere 6.0, which supports both read and write caching with vsphere vmotion, HA and other functions. Although SanDisk was VMware s VAIO design partner with respect to caching and is the first to set a shipping date for a VAIO-enabled caching product, it is not the only caching vendor that VMware has named as a future VAIO supporter. The others that have made the list so far are Condusiv Technologies, Infinio, HGST, PrimaryIO and Samsung. PrimaryIO like SanDisk demonstrated its VAIO-enabled software at VMworld last month in San Francisco. As previously mentioned, startup PernixData is claiming soaring sales for its vsphere-only caching software, and these are exceptional claims for this sector. PernixData s FVP software has impressive features, including support for both read and write caching and an unusual resilience to the use of VMware vmotion, since caches stay warm during VM movements. That results in its performance boost being unaffected by the use of vmotion as part of VMware s DRS load-balancing function, or for maintenance work. PernixData uses VMware s PSA API, which is clearly not part of VMware s plans for third-party caching integration. This means that unless PernixData reworks its software, it will not be managed by SPBM and will not gain the same VMware Ready status as its rivals. It will not even receive PVSP status for vsphere 6.0. PernixData is at present noncommittal about VAIO and says it has made no decision whether to support it.

5 SWOT ANALYSIS STRENGTHS VMware has bolstered the appeal of vsphere with VAIO by heavily extending integration with third-party products. SanDisk has raised its caching profile by being a VMware VAIO design partner, and looks likely to be the first of multiple vendors that will use VAIO to their benefit. WEAKNESSES VAIO is only present in vsphere 6.0, which only began shipping this year. Also, although VAIO addresses some of the major issues that may have been holding back adoption of server-side caching, it does not yet address all of them. OPPORTUNITIES VAIO will boost the prospects of the serverside caching sector. As flash prices continue to fall and customers storage performance problems continue to grow, buyers will consider alternative ways of using flash that are less disruptive and costly than the installation of new hybrid or all-flash back-end storage. THREATS VAIO alone may not be enough to bring the overall server-side caching market to life.