please also see
A brief update to the iSCSI vs. NFS in a VMWare environment based on 2012-2013 technologies.
I think the best vendor marketing campaign in recent storage history has been the full force attack of NetApp against iSCSI for use with VMWare. Now, I can fully understand NetApp not wanting any customers using their “iSCSI”,but iSCSI in general isn’t slower than NFS for VMWare. How do I know this? Well common sense for one, but let’s not bring my own personal emotions and experience into this conversation.
I think the best part of this marketing campaign was the release of a “white paper” or “tech report” or “case study”, whatever you want to call it. It was NetApp Technical Report TR-3697 – Performance Report: Multiprotocol Performance Test of VMWare ESX 3.5 on NetApp Storage Systems. I think the title explains the problem with this idea from the very beginning. The purpose of this report was the following:
Both NetApp storage arrays and VMware® ESX 3.5 natively support data access using three storage protocols: FC, iSCSI, and NFS. Due to the protocol flexibility and neutrality of both companies, many discussions have been had around the water cooler comparing the administrative pros and cons of the storage protocols as well as how they compare from a performance perspective in an ESX environment. This technical report, completed jointly by VMware and NetApp, shares the results of testing conducted to compare the performance of FC, software-initiated iSCSI, and NFS in an ESX 3.5 environment using NetApp storage. The results compare the performance of the three protocols with a goal of aiding customer decisions as they build out their virtual infrastructures.
Clear as day right? Well what is my problem with this approach? While NetApp does in fact support FC, iSCSI and NFS, they cannot claim to be the fastest FC, nor iSCSI block storage devices, and most likely are not the fastest NFS device on the market, however they are a NFS/CIFS device first and foremost. Why do I point this out? I’ll refer to an NetApp TechOnTap article. Within this article it points out that:
Block Storage Protocols
Initial NetApp storage systems were NFS appliances. Over the years, the same core
architecture has been extended to support multiple protocols—CIFS initially, and then
block-based protocols (Fibre Channel and iSCSI). Block protocols expose LUNs, which
are special WAFL containers (“files”) that exhibit block device characteristics. They
inherit the rich lineage of WAFL—including space- and resource-efficient Snapshot
copies and clones.
So what does this mean for an end-user? It means that when they create a FC or iSCSI volume on a NetApp filer, they are creating a very large file or “special WAFL container” that is virtualized out of the filer head as a raw block level device. Which, of course, an OS then needs to mount through another volume manager and then place a whole other file system on that. Clearly several layers of translation will increase latency and IO throughput.
So, where am I going with all of this? Clearly, NFS is going to be one of NetApp’s best performing protocols, because they have to build everything else on top of the file level architecture. Which leads me to my final comments. Released in a session at VMWorld 2008 in Europe was a direct comparison of NFS vs. iSCSI as far as performance. The title of the presentation is:
In this document iSCSI storage beat out NFS storage in performance, and with lower latencies. Take a look and see for yourself. So, when choosing a storage vendor, do some research, don’t just believe a “Tech Report“.
Comments always welcome….
- Tortoise and the Hare? (NFS vs. iSCSI and why this Apples to Broccoli) (thesantechnologist.com)
- VMware Partner Validated and Supported Solution: EqualLogic, Data Center Bridging, and VMware…the Perfect Combination! (en.community.dell.com)
- Building a Rackspace Private Cloud with Linux iSCSI Volumes | Knowledge Center | Rackspace Hosting (rackspace.com)
- How to Create an iSCSI LIF? (communities.netapp.com)
- UPDATE: Paragon Software Group Launches High Availability Storage Solution With Instantaneous Failover and Recovery (sys-con.com)
- Develop an understanding of DAS, NAS and SAN (communities.netapp.com)